CNS disease in dogs. Treatment of inflammatory diseases of the central nervous system in dogs. Features of dog training taking into account the type of higher nervous activity

A pinched nerve in a dog is a fairly serious disease. It is characterized by an acute onset - piercing shooting pains in the back, hindering movement. Alarming symptoms grow gradually, so the owner has enough time to take action and prevent the disease from moving into the acute phase, painful and difficult to treat.

Pinched spinal nerves are compression of the nerve roots extending from the spinal cord by adjacent vertebrae. The situation is complicated by the fact that the muscles surrounding the spine swell and reflexively spasm. Long-term compression leads to the death of nerve tissue, as a result of which the mobility of the dog’s limbs begins to suffer. Further development of inflammation is fraught with partial or complete paralysis of the animal.

There are several types of pinched spinal nerves. It depends on which part of the spine is involved in the pathological process:

pinched nerve of the cervical spine;
pinched thoracic nerve;
pinched sciatic nerve (sciatica).

Pinching of the upper spine (cervical and thoracic) can cause paralysis of the entire lower part of the dog's body. Pinching of the sciatic nerve causes severe pain and autonomic disorders in the dog. hind limbs leading to gradual loss of sensitivity.

Difficulties in diagnosis

Diagnosis of this disease has its own characteristics. It can be difficult to determine exactly where the pathological process is localized, since the pain is diffuse. Only a competent specialist can identify this. Therefore, if any peculiarities appear in the dog’s behavior, you should immediately contact a veterinary clinic. The owner should be alert to the following points:

the dog protects his back and doesn’t let him get close to him;
drags his hind legs;
whines when changing position;
reacts to weather changes;
refuses active play during walks;
spends a lot of time alone;
there is stiffness of movement.

Main causes of the disease

The disease, as a rule, is a consequence of pre-existing pathologies of the spine that are not diagnosed and not treated in a timely manner. Provocateurs of a pinched nerve can be:

spondylosis;
radiculitis;
intervertebral hernia;
spinal neoplasms;
injuries and damage to the back with displacement of the vertebrae;
posture disorders;
osteochondrosis;
metabolic disorders;
hypothermia.

Spondylosis

Spondylosis usually occurs in older dogs as a result of age-related changes in the vertebral segments. It is a degenerative-dystrophic process of the anterior sections of the intervertebral discs. The disorder is accompanied by the appearance of bone growths – osteophytes – on the anterior and lateral parts of the spine. Osteophytes can affect the nerve roots, narrowing the lumen of the spinal canal.

The disease actively progresses with spinal injuries, osteochondrosis, and decreased immunity. The risk group includes dogs with complicated heredity.

Spondylosis can affect the cervical or thoracic spine, but a particularly common location is the lower back.

The clinical picture of the disease is as follows: the dog’s movements become heavy and slow. She does not allow touching the back, much less using force during the examination. There is a deterioration in health depending on changes in weather conditions.

Spondylosis is diagnosed using an X-ray examination of the spine.

Radiculitis

A pinched spinal nerve can also cause radiculitis, an inflammatory lesion of the spinal cord roots. Its main symptom is severe pain. The disease can occur as a complication of osteochondrosis, as a result of hypothermia, injuries and infections. The risk group consists of dogs with developmental anomalies of various parts of the spine. Radiculitis can occur in chronic or acute form. There is also a complicated form of it – meningoradiculitis. It affects the membranes of the spinal cord.

Intervertebral hernia

Age-related changes in the spine or injury can lead to stretching or rupture of the fibrous ring of the intervertebral disc, which has lost most of its shock-absorbing properties. In this case, the gelatinous disc protrudes beyond its boundaries, compressing the spinal cord or its roots. Intervertebral hernia can be chronic or acute.

Spinal neoplasms

Spinal tumors sometimes cause damage to the spinal cord and major spinal nerves. This condition is irreversible and threatens severe paresis and even complete paralysis of the limbs. In this case, the dog will lose the ability to move independently. There are special wheelchairs for animals that replace the function of their legs and help them lead a fairly active life.

Symptoms of the disease

The severity and nature of the symptoms of the disease are determined by the degree of impairment of the sensitivity of the limbs:

A mild degree of the disease can be judged by moderate pain. The dog's behavior is relatively calm. Sensitivity is not impaired or slightly impaired. The animal is passive. Take care of your back, lie down carefully, avoiding sudden movements. Appetite is not impaired, body temperature is normal.
The average degree of the disease is characterized by fairly severe back pain, which the animal expresses with anxiety and plaintive whining. He rejects an attempt to examine his back with a growl. Muscle spasm is manifested by an unnaturally curved back and a tense abdomen (especially with sciatica).
Severe third degree of the disease is characterized by severe limitation of movements. The sacral spine and sciatic nerve are most often affected. At the same time, a “wooden” gait develops with unnatural tension in the legs. There is no appetite, body temperature may be elevated.

Treatment

A pinched nerve in a dog has painful symptoms, and therefore treatment should be aimed primarily at relieving the pain and only then treating the pinched nerve.

Symptomatic therapy

The main points of symptomatic therapy are:

relief of pain using painkillers;
stopping the inflammatory process in muscles and nerve roots using non-steroidal anti-inflammatory drugs (Quadrisol and Rimadyl);
prescribing sedatives that will help calm the pet and restore its nervous system;
providing the dog with complete rest and limiting movements.

Treatment of a pinched nerve

In order to relieve a pinched nerve in a dog, complex treatment is prescribed:

Vitamin therapy has a good effect. Animals are prescribed vitamins B1, B6, B12, which affect the conduction of nerve impulses.
Neuromuscular conductivity is well restored by the drug “Proserin”.
Stop the destruction of neuromuscular tissue by early stages homeopathic remedies help diseases.
To dissolve osteophytes on the vertebral discs, absorbable agents (Lidaza) are prescribed.
Physiotherapeutic procedures (massage and warming up diseased segments of the spine with a blue lamp) help relieve muscle inflammation.
If conservative therapy does not have the desired effect, the sick dog may be indicated surgery. But you need to know that such interventions are not always successful. The operation is quite traumatic for the spine and surrounding tissues.

Spinal pathologies should be treated exclusively in a veterinary clinic under the supervision of a specialist.

The prognosis of the disease with a mild course is often positive. But, if the course is severe, the prognosis is cautious.

Prevention

Not a single signal about a violation of the health of the dog’s spinal system should be left unattended by the owner. Every day you need to take care of maintaining the health of your pet and its physical development in accordance with age, namely:

You should exercise your dog regularly to strengthen its muscle corset.
It is imperative to give the animal timely rest. Active games, training and training sessions should be dosed.
It is important to feed your dog properly. The diet must be balanced and enriched with essential nutrients.
It is necessary to avoid hypothermia and colds, and monitor the state of the immune system.

A pinched nerve in a dog is treatable. A huge role in successful therapy is played by the attention of the owner and strict implementation of the recommendations of the attending physician. To avoid relapses, it is recommended to periodically conduct courses of maintenance therapy.

Many people notice that dogs often “adopt” the behavior of their owners and are distinguished by extremely wide manifestations of individuality in their character. These differences are mainly due to different types of nervous activity, and sometimes the causes of deviations are diseases of the nervous system in domestic dogs.

In order to understand the reasons for certain manifestations of an animal’s behavior, it is necessary to know the causes of the condition, be able to identify the disease in the early stages and understand when individuality ends and the disease begins. Basic knowledge will help you detect the disease at the very beginning and quickly cure your beloved dog.

Types of nervous activity in dogs

Classification by types of behavior has existed for a very long time and can be correlated with similar observations of human behavior. Based on character traits, it is customary to distinguish the following types:

Sanguines.
Cholerics.
Melancholic people.
Phlegmatic people.

This division, accepted for people, is also suitable for dogs. Scientific research in the field of nervous activity was carried out by Academician Pavlov. He introduced the concept of reflexes and derived three main properties of nervous processes:

force;
equilibrium;
mobility.

All types of reflexes were divided into unconditioned and conditioned. Unconditioned reflexes are also called innate, they are caused by the reaction of the nervous system to conditions environment. Conditioned reflexes are developed in response to certain influences, persist for as long as they are in demand, and fade away when the need for them ceases.

Not genetically transmitted. Conditioned reflexes are very important for dog training. The easier it is for an animal to develop a conditioned reflex, the easier and faster it can be trained.

According to the strength of nervous activity, dogs can be weak or strong, and this applies to both the stimulation of activity and its inhibition. This is a very important criterion, especially for service breed dogs. They must react quickly to changing situations and calm down just as quickly.

Mobility ensures quick transition from one activity to another. Nervous processes of this type can be reactive and inert.

Based on balance, dogs are divided into balanced and unbalanced types.

It cannot be argued that all types of higher nervous activity in domestic dogs appear in their pure form. As with humans, animals with mixed or transitional types of behavior are often found. The most common are dogs of the unrestrained type, which, according to the “human” classification, can be classified as choleric.

These are strong, sometimes even aggressive dogs who easily adapt to changes in the environment, easily form and fix conditioned reflexes, inhibitory reflexes are difficult for them and are developed with effort.

If such an animal is overloaded and given too difficult tasks, it becomes susceptible to neuroses. The excitable type of dog must undergo special training in order to develop adequate inhibition processes.
Dogs of the sanguine type are strong, energetic, very active, with sharp reactions and excellent sociability.

They easily form conditioned reflexes, just as easily move from strong excitement to concentration, and cope well with difficult tasks that require a quick and error-free choice of solution. Dogs with this type of nervous organization are better suited than others to perform official tasks.

Melancholic people are fearful, suspicious, and have weak processes of excitation and inhibition. Such dogs are always wary, they behave this way even towards their own owner. Developed conditioned reflexes quickly fade away.

Phlegmatic people are even less suitable for the role of a service dog. They react slowly and return to their original state just as sluggishly; they do not assimilate well. new information and quickly lose previously acquired skills. Rapid transitions from one type of nervous activity to another are practically impossible for them.

The behavior of a dog with abnormalities in nervous health can be pronounced or implicit, hidden. If a dog not only flinches at the sound of a bunch of keys unexpectedly falling on the tile, but begins to bark hysterically or even rush at people, there are clearly disturbances in the functioning of its nervous system. A healthy dog with a sanguine temperament will not even turn its ear towards the sound and will not “go crazy” itself.

Signs of a disease of the nervous system include seizures, sudden unmotivated mood changes, unreasonable aggression or complete apathy.

Brain diseases

Inflammatory diseases of the central nervous system in most dogs for the most part manifest themselves in such dangerous diseases as meningoencephalitis. This combined disease affects the meninges (meningitis) and the brain itself (encephalitis). Sometimes it “takes over” the spinal cord. Its lesion is called "encephalomyelitis".

The disease has the following classification:

By origin - primary or secondary meningoencephalitis.
By nature - purulent and non-purulent.
Depending on the course - acute and chronic.

In dogs, this disease manifests itself as a complication of a number of other diseases, for example, canine distemper, rabies, viral hepatitis and even helminthiasis (toxascariasis).

Symptoms of the disease are varied and vary at different stages. At the onset of the disease, the dog’s pupils are dilated, convulsions and twitching occur, which are sometimes confused with a condition such as a nervous tic of the head in an older dog. Rigidity of the neck muscles, agitation, and an acute reaction to any stimuli, including light and sounds, are also noted.

At further development Due to illness, the animal becomes apathetic, indifferent, does not respond to stimuli and stops following the owner’s commands, its coordination of movements is impaired, and its limbs are paralyzed. If the inflammation is acute and purulent, the body temperature rises.

Diagnosis is confirmed by puncture with collection of cerebrospinal fluid. Treatment is associated with eliminating the underlying cause of the disease. It is carried out comprehensively, the basis is the prescription of specific antibiotics.

In addition to encephalitis and meningoencephalitis, dogs may exhibit the following diseases caused by abnormalities in brain cells:

tumors of benign and malignant nature;
hydrocephalus;
idiopathic epilepsy and other diseases.

Problems associated with brain disease can be caused by external influences, such as an animal being hit by a car, being beaten by a person or other animals, or falling. The resulting injuries to the skull can have serious consequences, including damage to the brain. If they do not lead to the death of the dog or make it disabled, they may manifest themselves in changes in the animal’s behavior.

Spinal cord diseases

Spinal cord diseases in dogs are not caused by damage to the brain, but arise due to various effects on the spine and nerve endings. They may be caused for various reasons:

Spinal injuries and fractures.
Heredity. Some breeds with a long body and short crooked limbs have a hereditary predisposition to such diseases (dachshunds, basset hounds, English and French bulldogs, pugs, etc.).
Vertebral displacements.
Inflammatory processes.
Infections.

Herniated discs are most common in dogs with hereditary defects. In this condition, the disc becomes displaced and pinched between two vertebrae. The nerve endings are damaged, and the dog suffers from serious pain and impaired mobility.

Cauda equina syndrome can occur when there is severe inflammation or injury to the lumbar and pelvic spine. It develops a disease of the extremities, which constantly progresses and leads to persistent paralysis, dysfunction of the pelvic organs, genitourinary and excretory systems.
Unstable vertebra syndrome develops due to sudden movement of the head due to degeneration of the cervical vertebrae.

In this case, inflammation of the spinal cord membranes, a wobbling gait or the development of paralysis appears. It is believed that dogs with a long cervical spine, such as Great Danes and Dobermans, suffer from this more often than others. This condition is also often observed as a result of injury.

When injured and pinched with death of the end, there is no sensitivity in the affected area of the nerve, the animal cannot control the damaged part of the body, and paresis or paralysis develops.

Depending on the size and depth of damage to the spinal cord membranes, symptoms can affect different parts of the body. With massive lesions, the animal can be completely paralyzed.

Neuroses

These diseases are caused by the animal being in a stressful state for a long time. Usually the impact is so deep and intense that it leads to the development of permanent damage to the nervous system.

The difficulty in diagnosing neuroses is that each dog reacts differently, and the manifestations of pathology can differ dramatically. It is important to correctly identify the disease and separate it from behavioral disorders that can develop in an animal due to improper upbringing.

Neuroses are manifested by the following deviations in behavior:

Fear, panic states.
Apathy.
Aggression. This is a particularly dangerous deviation, since such an animal is capable of attacking absolutely any living creature, including a small child, pet or even your own owner.

Any neurosis can be treated as advised by Professor Preobrazhensky from Mikhail Bulgakov’s “Heart of a Dog” - “exclusively with love.” Since the cause of this condition is stress, you can cope with the animal’s condition by paying maximum attention to it. Feeling loved, it will be freed from the consequences of a stressful situation.

A striking and dangerous manifestation of the pathology of the nervous system is. This disease is associated with seizures and convulsions, which can be provoked by external stimuli, for example, sound and especially light. The disease is provoked by damage to a part of the brain of a non-infectious nature.

Epilepsy can be true and symptomatic. This disease is characterized by a regularly recurring series of short, fixed in duration seizures. The symptomatic form is associated with another disease, such as plague.

True epilepsy cannot be completely cured; symptomatic epilepsy can go away on its own after the cause that caused it is eliminated. For epilepsy, treatment will last the entire life of the dog. Correct diagnosis is important so that seizures are not mistaken by owners for this disease.

Hyperkinesis is pathological sudden involuntary movements caused by a failure in the conduction of nerve endings. Individual muscles or groups of muscles may be involved. Such manifestations are caused by organic or functional lesions of the nervous system, provoked by various factors.

Sometimes this condition occurs during treatment with antipsychotics due to harmful effects. In dogs, the disease manifests itself after traumatic brain injury, rheumatism, encephalitis or encephalopathy.

Various types of intoxication also play a major role, which is why there is no need to self-treat pets, especially with medications for humans. Poisoning can also be caused by medications left available to the dog, household chemicals and even cosmetics.

A nervous tic, which is often mistaken for a manifestation of a seizure, refers to hyperkinesis.

Treatment is prescribed by the doctor depending on the manifestation and severity of the symptoms, as well as what caused the problem. Anti-inflammatory drugs, drugs that improve cerebral circulation, antipsychotics, drugs to eliminate muscle rigidity, vitamins, restoratives, physiotherapy, and massages are prescribed.

Obsessive states

Some deviations in a dog’s behavior, which we often consider oddities, are actually obsessive-compulsive disorders, or obsessive-compulsive neuroses. Many of them are familiar to pet owners:

Circling behind your own tail.
Excessive, pathological neatness, when the dog literally spends hours licking itself.
Trying to chew out fleas that he doesn't actually have.
Sucking paws or tufts of hair on your body.
Eating objects that are not edible, including one’s own or someone else’s droppings.
Unmotivated aggression.

The mechanism is triggered by factors that are strong irritants for the sensitive nervous system. Treat obsessive states It is only possible in a comprehensive manner, using medications, replacement training and encouragement for correct execution of commands and calm behavior.

Other diseases of the nervous system

Aggressive conditions are most often observed in dogs as a reaction of the nervous system to sudden changes. For example, a sudden wave of the hand of a stranger or even a family member may be perceived as a sign of attack. The result can be twofold.

In dogs with a weak type of nervous constitution, this will cause fear and lead to hasty flight and a desire to hide. But more often, another effect is observed: the dog suddenly bursts into hysterical barking, while it can rush towards the person or hide behind the owner if it is frightened by a stranger.

Sometimes aggression is provoked by actions that are innocent from a human point of view - an attempt to pet a dog, a desire to straighten his bowl of food, and so on. If an animal has abnormalities in the functioning of the nervous system, it is impossible to predict its reaction.

A dog with deviations from the norm is not able to adequately perceive ordinary actions, gestures or events. Such dogs are usually discarded because they are a “time bomb” that can “explode” at the most unexpected moment.

Complications after injections

When treating diseases of the nervous system, the dog often has to receive injections. It is necessary to know the basic rules of injections and follow the rules of antiseptics, otherwise suppuration, abscesses, and in especially severe cases, sepsis cannot be avoided.

Intravenous injections can only be given by a specialist; intramuscular injections can only be given by the owner himself. In doing so, he must comply with the following rules:

Treat your dog as you would treat a person: check the expiration date of the drug, use disposable syringes and use antiseptics.
Wash your hands thoroughly before the injection, do not touch the syringe or ampoule.
Put a muzzle on the dog or secure its muzzle with wide bandages so that it cannot bite you.
Work together - one holds the animal, the other stabs.

If after the injection there is a “bump”, pain or suppuration in its place, immediately go to the veterinarian or call him home. These phenomena cannot be ignored.

Even more dangerous are damage to nerve endings. In most cases, they are temporary, but sometimes they can lead to impaired mobility of a part of the animal’s body. Veterinarians often have to deal with calls from upset pet owners like “I gave the dog injections, but the injections given to the dog got into the nerve plexus.”

This will lead to severe pain, numbness and dysfunction of the injured part of the body. It is especially dangerous if large nerve nodes are affected. This can cause mobility problems, lameness, dragging of the limb and many dangerous consequences.

If the owner is afraid or does not know how to give injections, it is better to entrust this to a veterinarian.

Physiological changes

Depending on the type of damage to the nervous system, changes in the dog’s body may include physical, psychological, and behavioral changes:

Problems with the sensory organs: the animal has difficulty hearing, seeing, cannot bark, or makes unintelligible sounds.
Impaired coordination of movements.
Ataxia.
If a limb is paralyzed, the dog may limp or drag its injured paw.
Seizures and convulsions. Symptoms of a nervous tic in a dog often appear; during a seizure, there is no reaction of the pupils to light, which can be considered signs of epilepsy.
Disturbances in the body's thermoregulation that occur when the nervous system is damaged lead to the animal's limbs becoming cold and cyanosis may be observed.
The dog does not recognize or reacts inadequately to its owners, to people in general, is apathetic or, conversely, overly excited, aggressive.
From the outside it may seem that the animal has suddenly forgotten everything it was taught before the injury or illness.
The reaction of the cerebral cortex in the first days after injury or the development of infection leads to either severe agitation or a lack of interest in life.
The reason for the increased weakness of the animal may be a brain tumor of various origins.

The appearance of any incomprehensible signs, including a change in the dog’s usual behavior, should alarm the owners and become a reason for an urgent visit to the veterinary clinic.

Diagnostics

Only an experienced veterinarian with special equipment can determine the type of disease of the central nervous system in a dog. It may be necessary to conduct an encephalography, examine the spine and skull bones using X-ray diagnostics to identify their damage, and undergo a computer or magnetic resonance imaging scan to detect changes in the brain or the presence of tumors.

In addition to these examinations, the veterinarian may prescribe a series of tests and an ultrasound scan. internal organs to determine possible damage.

Treatment

In all cases, treatment is always aimed at eliminating the cause, that is, the underlying disease. Purpose specific treatment carried out by a veterinarian depending on the dog’s disease and may include injections, oral medications, massages and physiotherapy courses.

If damage to the nervous system affects the behavior of the animal, the help of a correction specialist, as well as an experienced trainer, will be required. These people know how to treat such deviations. Taking action on your own to deal with such serious problems can greatly harm your pet’s health.

Risk factors

Any damage to the brain and/or spinal cord, or the nervous system as a whole can, at best, lead to individual disruptions in the functioning of the dog’s body, and at worst, cause damage to the sense organs, impaired mobility, paralysis and mental problems.

Risk factors that can lead to pathologies of the nervous system include the following:

Congenital problems arising due to genetic pathologies or intrauterine development disorders.
Severe infectious diseases, such as plague.
Injuries to the brain and nerve endings.
Cruel treatment of people.

Such negative impacts can have different effects on the animal’s body depending on their intensity and frequency of repetition.

Helping your pet at home

After being examined by a veterinarian and receiving the necessary treatment, the dog must go through a long rehabilitation process. The owners’ task is to provide her with peace of mind and competent treatment.

The animal should be provided with a quiet, shaded and warm place where it will not be disturbed. Pets should be warned not to disturb a sick animal. In case of severe injuries and paralysis, you will have to monitor the dog’s breathing rhythm, its hygiene and feeding.

Depending on the disease, treatment time can vary: from several weeks to lifelong. Owners will have to master the ability to give injections, massages and other manipulations that will be required to rehabilitate their pet.

Features of dog training taking into account the type of higher nervous activity

The selection of dogs for service functions, hunting and protection is directly related to the type of their higher nervous activity. If inhibition predominates in the behavior of an animal, and reactions are slow, it is completely unsuitable for performing such specific actions as protecting a home, owner or herd, hunting game and animals, searching and tracking, and so on.

However, such a dog, if properly trained, can very well become an excellent pet, a favorite of the whole family.

The nervous system establishes a connection between the dog’s body and the external environment, and also ensures the coordinated functioning of cells, tissues, organs and their systems as a whole. The activity of the nervous system underlies the functioning of its sense organs: vision, hearing, smell, taste and touch.
Anatomically, the nervous system is divided into:
- central, including the brain and spinal cord with spinal nerve nodes (ganglia),
- peripheral, consisting of cranial and spinal nerves connecting the central nervous system with nerve endings (receptors) of various organs.

The peripheral nervous system includes the following nerves: skeletal muscles and skin - the samotic part; internal organs and blood vessels - parosympathetic and sympathetic parts. The last two are usually united by the concept of the autonomic (autonomic) nervous system.

The nervous system is formed by nervous tissue, consisting of cells of different shapes - neurons, concentrated in the cortex or outer layers of the brain and spinal cord.

1 - nerve cell body; 2 - core; 3 - tree-like processes; 4 - neuritis; 5 - membrane, which together with the neuritis forms a nerve fiber; 6 - terminal branches of neuritis

A neuron consists of a body and processes: short dendrites (Greek "dedron" - tree), which receive nerve impulses, and long axons (Greek "axis" - process), transmitting impulses to the body. Each nerve cell has only one axon, the length of which can reach several tens of centimeters. Neurons also differ in function. Some neurons - sensitive (sensory)- transmit impulses from the sensory organs to the spinal cord and brain. The bodies of sensory neurons are located on the way to the central nervous system in the nerve ganglia. A ganglion is a collection of nerve cell bodies outside the central nervous system. Other neurons - motor neurons - transmit impulses from the spinal cord and brain to the muscles and internal organs.
The connection between sensory and motor neurons is carried out in the spinal cord and brain by interneurons, the bodies and processes of which do not extend beyond the brain. The spinal cord and brain are connected to all organs by nerves, which are a collection of long processes of nerve cells covered with a sheath. Nerves consisting of axons of motor neurons are called motor, and those consisting of dendrites, that is, sensory processes, are called sensory.

1 – spinal cord; 2 - sensitive neuron; 3 - bundles of nerve fibers; 4 - nerve sheath; 5 - leather; 6 - muscle; 7 - myelin sheath; 8 - motor neuron

Most nerves are made up of axons and dendrites. But there are also mixed nerves. The impulses travel along them in two directions.
For a novice dog owner, it is important to know the basic features of the nervous system, because the success of the initial and subsequent training of the animal will largely depend on this.
The main principle of the nervous system is that neurons of different functions are connected to each other in a chain, forming reflex arcs through which excitation is transmitted and reflex reactions of the body are carried out. Reflex usually called the body's response to irritation. This action is carried out and controlled by the central nervous system. The path along which nerve impulses are carried out during a reflex is called reflex arc. It has five parts: receptor, sensory pathway, part of the central nervous system, motor pathway and working organ.

1 - spinal cord; 2 - sensitive center; 3 - sensitive path; 4 - receptor; 5 - effector; 6 - motor path; 7 - synaptic transmission of excitation

Any nerve impulse in a reflex arc is first formed in a receptor (receiver), which perceives and converts a certain stimulus energy into an electrical impulse. The names of the receptors come from the nature (mechanism) of external or internal stimuli. For example: mechanoreceptors, thermoreceptors, photoreceptors and chemoreceptors. Mechanoreceptors respond to mechanical stimuli. These include tactile (tactile) ones, which are located on the skin, in the musculoskeletal and internal organs, as well as others. Thermoreceptors respond to changes in the temperature of the external and internal environment, photoreceptors (located in the retina of the eye) - to light (visual) stimulation. Chemoreceptors include taste, olfactory and internal organs that respond to changes chemical composition external and internal environment. In everyday living conditions, a dog’s body is exposed to many irritants at the same time. Impulses (signals) from each stimulus enter the cerebral cortex, where they are felt, or rather, analyzed. I.P. Pavlov, studying areas (zones) of the brain involved in a single connection with certain receptors, as well as the nerve conducting impulses, called this part (organ) of the nervous system an analyzer.
The dog’s body responds only to the most important stimuli. The reaction to less significant stimuli is inhibited, which leads to a more or less rapid adaptation (adaptation) of the body to the conditions external environment.
Thus, specialized peripheral and anatomical-physiological systems, with the help of which the dog perceives and partially analyzes various irritations, are called sensory organs. These include the organs of hearing, vision, smell, taste and touch.
It is important for a dog trainer to know some of the features (properties) that the senses have. For example, with the help of vision, a dog clearly sees a moving person at a distance of 500 - 700 m. The dog’s hearing organ is capable of perceiving and analyzing sound waves of up to 40 thousand vibrations per second: faint rustles that a person hears at no more than 6 m, the dog picks up with distances of 24 meters or more.
The dog's sense of smell is exceptionally highly developed, 11,500 times stronger than that of humans. A dog can distinguish up to half a million different odors.
Considering the nervous system, we can draw only one conclusion: the basic principle of the nervous system is reflex.
All reflexes are divided into unconditioned and conditioned.
Unconditioned reflexes (innate), in turn, can be simple and complex. Simple ones (withdrawal of the paw when it is pricked, salivation at the sight of food, constriction of the pupils under the influence of bright light, etc.) are carried out (manifest) as if automatically, that is, without habituation of the animal or participation big brain(in humans - thinking). Complex unconditioned reflexes manifest themselves in the form of instincts. Instincts, in turn, are divided into two groups: instincts of self-preservation (food, defensive, imitation, orientation, herd, play, etc.) and instincts aimed at preserving the species (sexual, parental).
Conditioned reflexes are also responses of the body to stimuli, but not innate, but developed under certain conditions. Knowing the basic rules for developing a conditioned reflex, you can easily learn to control the dog’s behavior and use it for various purposes.
The persistence of the manifestation of conditioned reflexes is not constant. They disappear if the conditions that caused them change. Conditioned reflexes are developed on the basis of unconditioned reflexes. To make it easier to understand this process, let’s consider the simplest example of a dog’s formation of a conditioned reflex to the command “Sit!”

So, the trainer gives the command “Sit!” (conditioned stimulus) and after this, that is, after 1-2 seconds, presses his hand on the dog’s lower back closer to the sacrum (unconditioned stimulus - mechanical). The command "Sit!" perceived by the dog's hearing organ. The impulses travel along the nerves to the auditory center of the cerebral cortex, where the first focus of excitation occurs. From hand pressure in the lumbar region, nerve impulses of excitation also arise, which along other sensory nerves reach the motor center of the cerebral cortex - a second focus of excitation arises. As a result of this impact, the dog sits down. If you repeat the actions of stimuli many times, a connection is formed in the brain (cortex) between the auditory and motor centers. And then, in the process of developing a reflex, we suddenly discover: it is enough to give only one command - “Sit!”, and the dog immediately, without using a second stimulus (pressure by hand), begins to sit down. This means: excitation in the cerebral cortex from the auditory center spread with a force capable of exciting the motor center, which transmitted impulses through the nerves to the muscles and caused them to contract.
Thus, the mechanism of formation of conditioned reflexes always comes down to the closure of connections between foci (centers) of excitation in the cerebral cortex. At the same time, all parts of the brain play a certain role in the formation of conditioned reflexes.

Most brain diseases are not infectious in nature and are associated with effects on the vessels of this organ, excessive high temperature. On a hot day, a dog owner should protect his pet from hyperthermia and sunstroke. All of these conditions are accompanied by similar symptoms, but are caused by different causes and require different treatments.

Hyperthermia occurs when the body as a whole overheats. In addition to the brain, hyperthermia disrupts the functions of all organs and systems. Most often, hyperthermia occurs in dogs locked in a car or other stuffy, easily heated room on a hot day. The risk group includes dogs of brachycephalic breeds, aging or obese animals and animals with diseases of the cardiovascular and respiratory systems.

Hyperthermia occurs when the external temperature is close to the dog’s body temperature; humid air and lack of drinking water increase the risk of developing hyperthermia. This is a very life-threatening condition for the dog, requiring immediate assistance to the injured animal.

In the most typical cases, body temperature rises to 42-44 degrees. The dog is depressed, breathing and heart rate are rapid, mucous membranes are white or bluish, vomiting, constriction or dilation of the pupils is possible. The dog cannot move, gets up with difficulty and immediately lies down again, shortness of breath increases, possibly falling into a coma and death.

Sunstroke occurs after being or active training in the open air, the midday sun is especially dangerous. Unlike hyperthermia, body temperature can remain normal, especially if the dog received sunstroke not during training, but in a calm state. Sunstroke is characterized by unsteadiness of gait, alternating slowing and rapid breathing, protruding eyes, and severe convulsions. Sometimes death occurs suddenly in a clinically healthy dog.

Practical recommendations: The dog should be moved to a cool place, cooled with a douche or cold compresses, given an enema with cold water. Injections of cardiac medications are necessary; if breathing stops, lobeline is given; in any situation, diphenhydramine is administered.

For pulmonary edema, intravenous injections of 40% glucose and calcium chloride are given.

During the recovery period, solutions of sodium chloride and ringer-lock are administered intravenously.

Disturbance of cerebral vessels

Poor blood circulation in the brain is associated with insufficient blood flow (anemia) or congestion of blood vessels (hyperemia). The latter can be active, caused by increased blood flow, and passive, manifested as a result of impaired blood outflow.

Active hyperemia occurs when active work in heat, fright, physical or emotional stress, as well as during transportation of dogs that are not accustomed to it various types transport. The dog quickly becomes agitated, becomes restless, irritable and abnormally fearful, reacts inadequately to external stimuli and can cause injury to itself or others. The dog barks, squeals, grabs air with its teeth, tries to run away, and sometimes vomits. Body temperature remains normal or slightly increased. But the temperature in the head area increases noticeably.

Congestive hyperemia most often it is a complication of heart disease, less often it occurs due to compression of blood vessels by tight collars or a growing tumor. Symptoms appear slowly, the dog is drowsy, apathetic, reflexes are weakened, and pain sensitivity is reduced. The dog is indifferent to everything, stands with his head bowed low, his appetite is reduced, his skin and mucous membranes are bluish in color. Body temperature remains normal. As congestive hyperemia progresses, the dog falls into a coma.

Anemia of the brain may result from severe blood loss, thrombosis, embolism, atherosclerosis or arteriosclerosis of the vessels supplying the brain, as well as compression of the vessels by a tumor or rope during an attempt to suffocate. In addition, brain anemia can be caused by various diseases blood, and heart disease accompanied by acute cardiovascular failure.

In the acute course of the disease, there is a sudden loss of coordination of movements, the gait becomes unsteady, and the dog may suddenly faint. The pulse becomes thread-like, breathing is intermittent, muscle tremors, sometimes cramps and convulsions occur. Mucous membranes are pale, scalp is cold. Possible vomiting and sweating of paw pads.

Chronic anemia is manifested by weakness, fatigue, decreased vision and hearing. For any physical activity shortness of breath, muscle tremors, and increased heart rate occur.

Practical advice: You should choose the right collar, prevent the dog from overtiring and promptly treat all diseases of the cardiovascular system. Early diagnosis and timely therapy are the key to success in cerebral circulatory disorders.

Inflammation of the brain and spinal cord and their membranes

Meningitis– inflammation of the membranes of the brain and spinal cord. Accompanied by increased intracranial pressure, dilated pupils, impaired coordination of movements, and tension in the neck muscles. Sometimes strabismus, paresis and paralysis of the limbs develop.

Encephalitis– inflammation of brain tissue. Characteristic symptoms are vomiting, photophobia, seizures similar to epileptic ones, drowsiness, paresis of the limbs, coma may develop.

Myelitis- inflammation of the spinal cord. Symptoms depend on where the spinal cord is affected, in the lumbar region, thoracic or cervical vertebrae. In any case, myelitis is accompanied common features infectious process: increased body temperature and impaired sensitivity in the paw pads.

Lumbar myelitis is characterized by paralysis of both pelvic limbs, with the absence of tendon reflexes and spontaneous release of feces and urine. Myelitis of the thoracic region is accompanied by spastic paralysis of the limbs, absence of abdominal reflexes and delayed defecation and urination, subsequently followed by incontinence. Cervical myelitis causes respiratory distress and often leads to the death of the dog.

The inflammatory process can spread from one part of the central nervous system to others, in which case meningoencephalitis, encephalomyelitis or meningomyelitis is observed. These conditions are characterized by even more severe disturbances of the nervous system and more severe symptoms.

Practical recommendations: at the first signs of a dog’s behavior disorder, a full examination should be carried out to identify inflammation at an early stage. The most reliable treatment procedure is MRI, and to select the most effective treatment A cerebrospinal fluid biopsy is required for bacteriological examination.

Bacterial inflammatory processes in the central nervous system are treated with antibiotics. All cases require the use of anti-inflammatory (metipred) and diuretics (mannitol, furosemide). For inflammatory processes in the central nervous system, antihistamines are prescribed. The use of immunostimulants is contraindicated, since the process of phagocytosis of infected nerve tissue cells leads to a worsening of the dog’s clinical condition.

About the gentle canine psyche

Anyone who believes that there is no place for neuroses and stress in a dog’s life is seriously mistaken. The complexity of the psyche of a person’s first friends allows them to receive serious mental trauma, followed by one or another disorder of nervous activity.

TO neuroses predisposed to sports and service dogs in case of gross violations during training. Often neurosis is caused by beating the dog, frequent blood taking, or prolonged absence of the owner. It is especially difficult for dogs to tolerate a change of owner or area of use, for example, the transfer of a hunting dog to guard duty, on a chain.

Symptoms: Persistent loss of appetite, agitation and aggression, followed by depression, fearfulness and an attempt to hide. Urination becomes more frequent, unconditioned reflexes become stronger and conditioned ones become distorted. For example, a dog in a state of neurosis is characterized by an inadequate reaction to well-known commands. The pulse becomes rapid and arrhythmic.

Stress, disadaptation syndrome differs from neurosis in its chronic course and arises from prolonged exposure to strong stimuli on the psyche. Most often, dogs experience transport and emotional-pain stress. Transport stress manifests itself immediately or 2-3 days after transporting the dog and is accompanied by agitation, intestinal dysfunction (more often diarrhea than constipation), and sometimes convulsions.

Emotional-painful stress is characterized by a successive change of stages: 1) the anxiety stage with decreased performance and increased restlessness, 2) the adaptation stage, during which the dog looks completely healthy, and 3) the disadaptation stage, accompanied by depression and intestinal dysfunction, less often pneumonia.

Practical recommendations: It should be remembered that the dog’s body takes quite a long time to recover from a strong impact on the nervous system: in mild cases, 7 days, in severe cases, more than 20 days. In case of severe stress syndrome, the development of coma and death of the dog is possible, puppies are especially susceptible to this. dwarf breeds.

A dog in a state of neurosis or stress should be kept calm and good food. An important condition recovery is the elimination of the traumatic factor. They use sedatives and, if necessary, anticonvulsants, glucose, vitamins and adaptogens, such as Leuzea extract, ginseng and Schisandra chinensis.

About epilepsy and other seizure conditions

True epilepsy is rare. This is a hereditary imbalance between the processes of excitation and inhibition in the cerebral cortex. The disease is chronic and manifests itself as periodically occurring convulsive activity with loss of consciousness and reflexes.

True epilepsy is incurable; helping a dog with this disease involves the use of anticonvulsants and sedatives.

The situation is complicated by numerous diseases accompanied by attacks that are clinically no different from epileptic ones. These are the consequences of bruises and concussions, disruption of the integrity of the eardrum caused by ear mites, severe intoxication.

The cause of seizures can be a lack of calcium, magnesium and glucose, as well as a different sodium content in the blood than normal. It is not uncommon for seizures to occur due to a tumor, dropsy, abscess or inflammation of the brain. Conditions similar to epileptic seizures may be accompanied by carnivore plague, lack of oxygen caused by heart or lung diseases, acute hepatitis, chronic kidney disease, poisoning with organophosphorus compounds and other household chemicals.

Symptoms: The most typical is a suddenly occurring convulsive seizure; less often, before the seizure, a change in the dog’s behavior is noted: aimless walking, increased fearfulness, causeless anxiety. During an attack, the dog falls to the ground, the pupils dilate, the head is thrown back, the muscles of the head, neck, limbs and back tense and twitch, and consciousness is lost. Foamy saliva comes out of the mouth, the dog convulsively opens and closes its mouth. Breathing becomes hoarse, and involuntary release of urine and feces is observed. The mucus is bluish. The convulsions become violent and last 2-3 minutes.

Practical recommendations: Any seizure should not be considered a manifestation of epilepsy; it is necessary to examine the dog and find out the real reason painful condition. Many causes can be eliminated, allowing your dog to live a calm life without life-threatening seizures. Corvalol can be used as a first aid remedy for a convulsive attack.

Eclampsia is a disease of lactating dogs

Eclampsia– these are attacks of convulsions that occur in dogs in the first 2 weeks after birth, less often during pregnancy or after the end of lactation. Sometimes eclampsia is observed in puppies in early milk age.

Cause: Postpartum hypocalcemia also occurs in dogs that receive large amounts of calcium during pregnancy. Consequently, the lack of this mineral in food is not the only cause of the development of the disease. It has been revealed that eclampsia accompanies any disorder of calcium metabolism, with its excess or insufficient intake from food. With an excess of calcium, the activity of the parathyroid glands is suppressed and the production of parathyroid hormone, necessary for the absorption of calcium, is inhibited.

Symptoms: Early signs are increased excitability and rapid breathing. If left untreated, increased drooling, stiffness of gait, impaired coordination of movements and convulsions occur. Seizures recur after 10-30 minutes. The calcium level in the blood is low. Aspiration pneumonia is a common complication of the disease. In severe cases of eclampsia, the dog may die from pulmonary edema.

Practical recommendations: It is necessary to balance the dog’s diet with calcium, magnesium and phosphorus. To relieve a convulsive attack, a 10% solution of calcium gluconate is administered intravenously. The injection should be done very slowly and stopped at the first sign of a slow heartbeat or arrhythmia.

After normalization of heart function, calcium administration continues. To prevent recurrences of seizures, calcium borogluconate is administered subcutaneously at a dosage of 0.5 ml per kilogram of the dog’s weight 3 times a day for 1-2 days. The dog is prescribed vitamin preparations, with special attention paid to vitamin D. If, despite treatment, seizures occur again, it is recommended to remove the puppies from the dog and feed them artificially.

Vestibular disorders

Violation of the vestibular apparatus is manifested by a complex of symptoms: head tilt, trembling of the eyeballs and impaired coordination of movements while maintaining muscle tone. There are quite a few diseases accompanied by such a clinical picture, so it is very important to establish an accurate diagnosis.

It is especially important to distinguish between disorders of the vestibular apparatus caused by damage to the central nervous system (cerebellum and nerve centers) and caused by damage to the peripheral part of the vestibular apparatus (structures of the middle ear). The latter can be successfully treated, in contrast to lesions of the central nervous system, in which the chances of success are much less.

Causes of damage to the peripheral part of the vestibular apparatus:
– Inflammation of the middle ear due to prolonged external otitis or pharyngeal infection.
– Neoplasm of the middle ear.
– Head injury, palpation is accompanied by severe pain.
– In purebred dogs ( German Shepherd, Cocker Spaniel, Doberman, Akita Inu) there may be congenital disorders of the functioning of the vestibular apparatus. Symptoms appear from birth to 3 months of age, but examination shows the absence of organic damage in the middle ear area.
– Degenerative changes in the vestibular apparatus caused by long-term use of antibiotics in excessively high doses. The most dangerous are aminoglycosides (gentamicin, kanamycin).

Causes of damage to the central part of the vestibular apparatus:
– Inflammation of the brain and its membranes. Most often, meningoencephalitis complicates infections: canine distemper, granulomatous meningoencephalitis, cryptococcosis, toxoplasmosis, rickettsiosis.
– Brain tumors. Most often they affect dogs over 5 years of age, but meduloblastomas and choroid plexus papillomas can also occur in young dogs.
– Thiamine deficiency. Most often it occurs when fish or low-quality industrial food predominates in the dog’s diet.
– Skull injuries with bone fractures and indentation of their fragments.
– Congenital enzymatic deficiency, leading to disruption of fat metabolism and accumulation of substances toxic to the nervous system. Symptoms appear around one year of age. In addition to disorders of the vestibular system, there is growth retardation, liver enlargement and curvature of the hip joints.

Symptoms: The dog walks with an unsteady gait, bent over, and may fall on the side of the injury. Her head is tilted to the same side, and sometimes her spine is curved. With more severe injuries, movement in a circle in the direction of tilting the head and vomiting are observed. In the first week after damage to the vestibular apparatus, rhythmic trembling of the eyeballs (nystagmus) occurs, which subsequently compensates by itself.

With a bilateral lesion, the dog prefers to sit, and an attempt to move ends in falling on one side or the other. There is no head tilt or nystagmus, and deafness is possible.

The diagnosis is made after a neurological examination, radiography of the skull, and taking fluid from the middle ear cavity and spinal cerebrospinal fluid for bacteriological culture.

Practical recommendations: You should take ear inflammation seriously and not self-medicate. Do not use aminoglycosides unless absolutely necessary; if there is no other option, treatment should be carried out under the supervision of a physician. Adequate feeding, regular vaccination, and timely removal of tumors of the auricle will protect the dog from the main causes leading to disorders of the vestibular apparatus.

Non-inflammatory spinal cord injuries

Most often, owners of dachshunds encounter myelopathies, but disruption of innervation and paralysis of the pelvic limbs can develop in any dog. The fact is that there are quite a few reasons leading to the same result - narrowing of the spinal canal and compression of the spinal cord or its roots.

Degenerative changes in intervertebral discs. These are age-related changes in the structure of cartilage tissue, characteristic of dogs. large breeds. The intervertebral discs of older dogs become harder, no longer cushion, and become deformed over time, which can lead to cartilage embedding into the spinal canal.

Symptoms: The disease is chronic, at first there is slight stiffness in movements, then the pain increases, and the dog increasingly loses its mobility. From the moment the disc substance is inserted into the spinal canal, the dog begins to shuffle with its paws, erasing the outer surface of the fingers, sometimes it becomes completely impossible to move.

Treatment: In the early stages, the development of the disease can be stopped by changing the diet, proper motor activity and physiotherapeutic techniques. In later stages, only surgery is effective. But even this gives only a temporary effect, since pathological changes affect the entire spine and can appear at any time in another area.

Chondroid metaplasia of the nucleus pulposus is the transformation of the liquid substance of the intervertebral disc into hyaline cartilage, which is squeezed into the spinal canal and disrupts the blood supply to the spinal cord. There are breeds that are predisposed to such changes - these are dachshunds, poodles, French bulldogs and pugs. Contrary to popular belief, elongated shape body has nothing to do with this disease. For example, beagles do not suffer from chondroid metaplasia.

Symptoms: The dog is in severe pain, dragging its motionless pelvic limbs behind it. The speed of assistance is of great importance - the compressed nerve endings die and the later the problem is eliminated, the less chance there is for the dog to fully recover.

Treatment depends on the degree of damage: if the sensitivity of the limbs is preserved, and the dog does not have paralysis, but only a lack of coordination of movements, conservative therapy (immobilization, rest, metipred) is possible, and if paralysis is observed, the damaged area is localized using MRI and surgery is performed. If there is no sensitivity in the pelvic limbs for more than 48 hours, then even surgical treatment will most likely not help, since irreversible changes have occurred in the nervous tissue.

Compression of the spinal cord by a vertebral fragment due to injury or a growing tumor. These conditions require surgical treatment in a specialized clinic.

Symptoms depend on the nature of the damage and in which part it is localized:
Damage in the cervical region is accompanied by muscle stiffness, pulsation of the anus and involuntary movements of the tail, in the thoracic region there are no reflexes of the thoracic limbs, in the lumbar region the dog sits with its hind legs stretched forward along the body. Reflexes on the forelimbs are preserved, but on the hind limbs they are enhanced. The most typical damage to the vertebrae is in the lumbosacral region - the front part of the body moves normally, the entire back part is paralyzed, the tail hangs down, the anus gapes, defecation occurs involuntarily.

Spinal cord ischemia. A relatively rarely diagnosed pathology associated with blockage of the vessels supplying the spinal cord with particles of fat. It is observed in dogs with increased concentrations of cholesterol in the blood and disorders of fat metabolism. A breed predisposition to this disease has been identified in miniature schnauzers.

Symptoms: A painful swelling forms in the area of the damaged area of the spine, the sensitivity of the skin and muscles of the underlying areas of the body is impaired, as well as coordination of movement. Depending on the degree of damage, either a complete recovery or the death of the dog is possible.

Treatment is conservative and involves eliminating the cause and restoring blood vessels. Surgical intervention not required because the spinal cord is not compressed. But to make an accurate diagnosis, an MRI should be performed to make sure there are no other causes.

Practical recommendations: Any conservative treatment of diseases associated with spinal cord damage without making an accurate diagnosis is a gamble, which can result in disability or death of the dog. There's no need to be afraid diagnostic studies under anesthesia (MRI) and surgery - his life depends on how wisely you approach the treatment of your pet.

The material was specially prepared
website for dog breeders portal
veterinarian Kalashnikova O.V.

Granulomatous meningoencephalomyelitis (GME) is an inflammatory disease of the central nervous system in dogs that is characterized by localized or widespread granulomatous damage to the brain or spinal cord. An inflammatory process associated with the accumulation of so-called mononuclear cells in perivascular tissues: lymphocytes, monocytes and macrophages; the process is not accompanied by exudative phenomena. The etiology of this disease remains unknown, although the autoimmune nature of the disease is considered the most likely cause. This paper examines the clinical signs of the disease, as well as opinions regarding the etiology and nature of the processes occurring in the tissues, from the point of view of different researchers.

Introduction

Granulomatous meningoencephalomyelitis (GME) is an idiopathic inflammatory disease of the central nervous system (CNS) in dogs. The pathology was first described by Braund and colleagues in 1978. Subsequently, various veterinarians reported similar cases. Previously, the disease was not accurately diagnosed, therefore, as understanding of the processes developed, granulomatous meningoencephalomyelitis began to account for up to a quarter of all inflammatory diseases of the central nervous system in dogs. More accurate diagnosis has also become more common with the advent of techniques such as MRI and CT.

Pathology

On histological examination, lesions characteristic of GME are detected predominantly in the white matter of the central nervous system and are characterized by the formation of dense conglomerates of accumulations of inflammatory cells arranged in a spiral pattern around blood vessels. These perivascular collections (Fig. 1) include mainly macrophages along with varying numbers of lymphocytes, monocytes, plasma cells, some neutrophils, and multinucleated giant cells. Lymphocytes and macrophages are found in most lesions and the greatest number However, some granulomas are composed predominantly of lymphoid cells, and not only around the vessels, but also extend away from the granulomatous tissue around the vessels. Typically, lesions are found in a variety of areas of the central nervous system, but most often occur in the white matter of the brain, cerebellum, brainstem, or caudal cervical spinal cord. Comparable lesions may also be observed in the gray matter and may involve the vasculature of the arachnoid or the vasculature of the brain tissue itself.

Figure 1. Sections from brain tissue affected by GME:

a) section demonstrating the nature of perivascular lesions, the formation of so-called “cuffs” containing predominantly mononuclear cells around blood vessels. Staining: hemotoxylin and eosin, magnification × 40.

b) The photo shows the typical swirling patterns of clusters in the white matter of brain tissue.

Three forms of GME have been described primarily on the basis of clinical features: focal, widespread (multifocal), and ocular. However, in both focal and widespread forms, the lesions tend to be widely scattered throughout much of the central nervous system. In the focal form, adjacent granulomas merge, which leads to a volumetric lesion, which demonstrates the clinical picture, depending on the location. Focal lesions are more common in the brain and brain stem.

Pathogenesis and etiology

The pathogenesis of GME is unknown, but three possible etiologies are considered:

The infectious nature of the disease has been proposed by a number of authors. However, no convincing evidence has been obtained for any infectious agent.

Considering the frequent cases of development of GME for some time after routine vaccination, some authors reasonably believe that the development of the disease is associated with an aberrant response to the introduction of the canine distemper virus or even the development of an autoimmune response after vaccination. However, there have been only sporadic reports of the identification of plague virus using immunohistochemistry or serology. Although you need to understand that in autoimmune damage after suffering from plague, it is not the persistence of the virus that occurs, but secondary autoimmune disorders.

The causative agent of toxoplasmosis has also been considered, but there is no confirmation of this assumption.

Researchers Sutton and Atwell reported two cases of the development of GME in dogs after the use of levamisole (levamisole, in addition to anthelmintic properties, is known to have immunomodulatory properties). This fact may indicate a reaction to a previously hidden antigen, possibly of infectious origin or stimulation of a latent autoimmune process.

There is an assumption about the role of a retroviral infection that accidentally got into the vaccine.

There is evidence of a genetic role in the development of GME.

Autoimmune etiology is considered the most likely and was proposed by Kipar et al. and Wong and Sutton. Immunohistochemistry showed that among the inflammatory cells in the lesions, MHC class II antigen-positive macrophages (major histocompatibility complex) and antigen-positive T lymphocytes predominated. These findings may indicate a T cell-mediated delayed-type hypersensitivity reaction characteristic of autoimmune and allergic responses.

Also, especially with focal lesions in GME, the tumor nature of the pathology was postulated, since such lesions may have a variable index of mitotic activity with varying degrees of pleomorphism. This has been shown in cases with focal GME and may represent a misdiagnosis of the etiology of the lesion: CNS lymphoma or a neoplastic disease of another origin.

Epidemiology

GME is most common in young and adult toy breed dogs. However, there is wide variation in the data reported among different breeds dogs. Table 1 includes “classical” data, presented along with possible “scatter” in age and breed.

Table 1

As with most CNS diseases, the clinical signs observed in animals with GME primarily reflect and are related to the location of the inflammatory lesions rather than characteristic symptoms the pathology itself.

Table 2 shows the typical clinical symptoms that are observed with lesions in each of the major areas of the brain. Table 3 provides a summary of the clinical symptoms that have been observed in reported cases of GME presented in the literature.

Table 2 Summary of clinical features typically associated with lesions in specific brain regions

Forebrain: cerebral cortex and thalamus	Cerebellum
Convulsions	Ataxia
Changes in the dog’s behavior (refusal to follow commands, aggression, increased excitability)	Tremor
Changes in neurological status (apathy, depression, disorientation, lethargy, coma)	Hypermetry
Abnormal movements, postures (movement in circles, aimless walking)	Widely spreads limbs position
Neurological deficits: postural reactions, threat test, visual impairment	Normal reaction to threat test, normal vision
	No weakness
Midbrain	Hypothalamus
If the upper motor neuron is affected: paresis or paralysis of all four limbs or only one side	Normal gait
Postural deficits in all four limbs or only on one side	Change in mental state (disorientation, lethargy, coma)
Depression, coma	Changes in behavior (aggression/excitability)
Deficiency of oculomotor function on the affected side	Bilateral cranial nerve II deficits at the optic chiasm
Hyperventilation	Abnormal movements/postures (stiff circling, pacing, wandering, head pressing, trembling)
	Hyperthermia, hypothermia
	Abnormal appetite
	Endocrine disorders
	Convulsions
Damage to the vestibular system (part of the nervous system)	Brain stem
Head tilt	Hemiparesis or asymmetric tetraparesis:
Nystagmus - positional, vertical, horizontal, rotary	Upper motor neuron signs
Ataxia	Postural response deficit on the affected side
	Clinic of lesions of cranial nerves: V-VII, IX-XII
Behavior change	Depression
	Dyspnea

Table 3 Frequency of clinical signs described in 151 GME cases reported in the literature

Clinical signs	Number of cases
Head tilt	6
Nystagmus	1
Convulsions	11
Changes in behavior	7
Depression	10
Ataxia	38
Proprioception deficit	16
Deficit of postural reactions	5
Dysmetria	11
Shiver	6
Hyperesthesia	15
Paresis of the pelvic or thoracic limb	17
Cranial nerve deficiency	17
Blindness/decreased vision	15
Facial nerve paralysis	1
Fever	19
Neck pain	37
Forebrain lesion	25
Trunk damage	15
Vestibular apparatus	13
Cortical lesions	11
Cerebellum	13
Myelopathy	7
Spinal cord lesion	4

Animals with the disseminated form of the disease have signs demonstrating dysfunction in two or more locations: the brain, brain stem, cerebellum, spinal cord, meninges, and optic nerve. This disseminated form accounts for approximately half of all reported cases of GME.

The local form of GME is characterized by signs characteristic of one of the syndromes listed above. Thus, depending on the location, this lesion may demonstrate impairment of movement, proprioception, vestibular system, etc. The most commonly found signs reflect lesions in the brain and brain stem. However, localization can be very different. The local form of GME also accounts for about half of all cases and, usually, the intensity of the increase in the clinical picture is much slower (within several months) than with disseminated forms.

Despite the fact that the widespread form has an acute onset, and the focal form is more extended over time. There is great variability in the course of the pathology, which is associated not only with the degree of prevalence, but also with the speed of development of pathological processes in the nervous tissue. Demierre et al. found that the course of the disease does not correlate with the area of damage, but with the degree of cellular infiltration, that is, the degree of tissue destruction.

The ocular form of GME is quite rare and, as a rule, is characterized by the sudden onset of blindness due to optic neuritis, sometimes accompanied by uveitis, less often with retinal hemorrhage. As a rule, the disease is bilateral, but it can also be unilateral. In a number of dogs that develop the ocular form from the very beginning, the pathology can subsequently progress and lead to damage to other parts.

Diagnostics

Blood tests rarely provide enough information to accurately diagnose GME. In some cases, mild or moderate leukocytosis is detected, although most often no characteristic changes in the blood are detected. Cerebrospinal fluid (CSF) analysis is the mainstay of diagnosis, but large differences and variations in the results of such tests may not provide a complete picture of the pathology. Figure 2 shows cerebrospinal fluid cytology from GME.

Table 4 shows the classic features of GME and the variations that can also be expected.

Table 4. Changes in CSF during GME

Figure 2. Image of a cerebrospinal fluid sample. Cytology demonstrates mononuclear pleocytosis in GME. Magnification × 40.

When scanning the central nervous system using magnetic resonance imaging (MRI) and computed tomography(CT) in most cases, space-occupying formations are detected, which also cannot be definitively differentiated from neoplasms. But the combination of the identified picture with age and prevalence can, based on the study, suggest GME. Distinctive feature GME cases are a more dense picture of areas with damage to brain tissue. A definitive diagnosis can only be demonstrated by a biopsy of the tissue lesions.

Differential diagnosis

As discussed above, the observed clinical signs most commonly relate to the location of the lesion rather than to its nature. Thus, the list of possible diagnoses that will be considered is often broad. Signs of focal CNS involvement can occur with any mass lesion (eg, neoplasm, inflammatory granuloma, cyst, or infarct). Additionally, there are many possible causes of optic neuritis. Thus, the clinical data are far from concrete.

CSF analysis demonstrates mononuclear pleocytosis, which can also occur with:

viral encephalitis (for example, plague). To exclude canine distemper, it is necessary to conduct a serological blood test for canine distemper virus, as well as PCR on CSF samples for the presence of canine distemper virus.

Protozoal encephalomyelitis (toxoplasmosis, neosporosis)

The above diseases are of greatest interest for differential diagnosis. In addition, it is necessary to distinguish infections from GME by carefully examining the patient for extranervous lesions of the central nervous system, since infections may have other clinical signs of chronic infections and other diseases;

Fungal encephalomyelitis (cryptococcosis)

In fungal infections of the central nervous system, there is usually a predominance of eosinophils in CSF samples and the fungal elements themselves.

There is reasonable evidence of the existence of acute, severe, both multifocal and diffuse diseases of the central nervous system of a necrotic nature. As a rule, Necrotizing meningoencephalitis in dogs is characterized by non-exudative inflammation of brain tissue with a predominance of alterative processes (necrosis). Necrotizing meningoencephalitis is identified as a separate nosological unit. It is found mainly in certain breeds: for example, Pointer, Pug, Maltese Terriers, Pekingese and Yorkshire terriers. Necrotizing meningoencephalitis manifests itself with characteristic syndromes;

Tumors. Some cases of CNS lymphomas are interpreted as GME. This is not surprising, since with CT/MRI studies the manifestations of these diseases may be the same.

Typically, corticosteroids are used, particularly prednisolone, at immunosuppressive doses (2 mg/kg/day) and tapered over several months to reach the lowest dose that will maintain improvement. However, dose reduction sometimes leads to disease progression. In cases where long-term use of prednisolone produces side effects, the possibility of therapy is significantly reduced.

IN Lately list treatment regimens is expanding. There is no widespread use of cytostatics to be able to evaluate the real results of such therapy. Some of these agents that have been used for GME are listed below:

- azathioprine is used in combination with corticosteroids to reduce the dose of the steroid and avoid the unwanted side effects of long-term steroids;

- cytosine arabinoside is an antitumor agent that acts on dividing cells by blocking pyrimidine synthesis and causing premature termination of the DNA chain. This drug is used to treat lymphoma and myeloproliferative diseases in human and veterinary medicine and, according to recent data, has demonstrated success in the fight against GME.

- cyclosporine, has a pronounced suppressive effect on T-cell function, but has also been used in a number of cases with positive results.

There is evidence in the literature about the effectiveness of radiation therapy. In a number of dogs with GME, the quality and longevity of life were statistically significantly longer in comparison with animals treated with other methods.

This video partially demonstrates the clinical picture of ataxia and loss of coordination in GME, as well as the possibility of hormonal therapy

When diagnosed with GME, the prognosis in the vast majority of cases is unfavorable. Most studies conclude that dogs with multifocal disease typically have a short life expectancy (up to 100 days from diagnosis). Dogs with focal disease tend to have a longer survival period (eg, three to six months). There are anecdotal reports of dogs showing no disease progression over a longer period.

— The clinical picture of GME can be very different. Dogs can present with either acute or chronic disease, with focal or multifocal lesions of the central nervous system.

GME is a complex disease from a diagnostic point of view; to definitively identify it, a careful differential diagnosis is required, in which the leading factor is the detection of mononuclear pleocytosis in the cerebrospinal fluid in a combination of CT/MRI data.

Corticosteroids currently remain the mainstay of therapy, but due to their lack of comfort side effects when using hormones, a search for new ones is required medicines and methods.

References

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