Inflammatory diseases of the central nervous system in dogs

Encephalitis in a dog is an inflammatory process that affects the animal’s brain. The disease develops against the background of an infection or allergy and may affect the spinal cord. Encephalitis is treatable if diagnosed early. As a rule, this problem is difficult to detect in the early stages, so it is necessary to put a lot of effort and patience into the fight for the health of your pet.

Types, stages and causes of disease development

In veterinary medicine, several types of encephalitis are known, which differ in the localization of the affected areas and organs.

Types of disease:

1. Encephalomyelitis is damage to the animal's brain and spinal cord.
2. Meningoencephalitis is an inflammatory process that affects the brain along with the membranes.
3. Meningoencephalomyelitis is the presence of disorders of the dog’s spinal cord, as well as the membranes of the brain.

Depending on the cause that caused the development of the inflammatory process, the disease can occur in the primary and secondary stages.

Reasons for the development of primary encephalitis:

• viruses;
• bacteria;
• protozoan parasites;
• Tick-borne Encephalitis.

Secondary encephalitis occurs as a complication against the background of other diseases.

Causes of secondary encephalitis:

• bacteremia;
• purulent otitis media and other purulent processes;
• weakened immune system;
• sepsis;
• head injuries.

Some dog breeds have a hereditary predisposition to encephalitis. The disease is most often observed in beagles, Bernese Bouviers, Yorkshire terriers, pugs and Maltese dogs. These types of animals require increased attention from their owners to any health problems.

Meningoencephalomyelitis in dogs and cats

The fashion for dogs of miniature breeds, which began in Russia, brought with it the emergence of pathologies that previously veterinary doctors could only read about in the scientific works of doctors of the previous generation. Meningoencephalitis has not been reported in dogs, at least for the last 20-30 years. Of course, we are talking about a frequent manifestation of the disease; isolated cases occurred during this period, but very rarely.

Specialists at VC DobroVet explain this not only by the popularity of such breeds as Yorkshire terriers, Chihuahuas, toy terriers and other babies, but also by the emergence of more advanced diagnostic equipment, in particular CT and MRI, with which you can accurately make a diagnosis.

Among the “new” pathologies, MEM (meningoencephalomyelitis) is especially distinguished, which most often occurs in decorative breeds of dogs, sometimes in large ones and even in cats.

There are two forms of the disease:

- “non-infectious” idiopathic meningoencephalomyelitis;

- “infectious” with an identified pathogen.

Most often, veterinary specialists at DobroVet VC have to deal with idiopathic MEMs, the cause of which has not been established.

Reasons for the development of MEM in animals

Inflammatory diseases of the brain can be caused by pathogens (infectious): Ehrlichia spp., Anaplasma phagocytophilum, Rickettsia rickettsii, Borrelia burgdorferi (the causative agent of Lyme disease), Bartonella vinsonii subspecies berkhoffi.

MEMs of viral origin occur in the presence of the following diseases:

Viral origin: canine distemper, feline immunodeficiency virus, rabies, feline leukemia, infectious peritonitis in cats.

Protozoa: Toxoplasma gondii, Babesia spp and Neospora caninum;

Pathogenic fungi: Blastomyces dermatitidis, Aspergillus spp, Cryptococcus spp, Coccidioides immitis;

Helminths: Dirofilaria immitis and Angiostrongylus vasorum;

Granulomatous meningoencephalomyelitis (GME) is the most common type of GME. Previously, this disease was called inflammatory reticulosis. The lesion mainly affects the white matter of the brain, as well as the spinal cord and brain.

GME forms:

— disseminated (not widespread, but contained in loci) development time 1-8 weeks;

For this disease, there is a characteristic histological picture - perivascular granulomatous inflammatory lesions with a high concentration of histiocytes and a small number of lymphocytes, neutrophils and eosinophilic granulocytes.

Inflammatory foci can merge into one and massive lesions of the brain stem, spinal cord and cerebral hemispheres occur.

Ophthalmic form of GME – damage to the optic nerve occurs.

The cause of GME has not been fully established. There are several versions of the origin of the disease, but none have been fully confirmed.

Clinical signs of the disease depend on the location of the pathological process.

Animals typically experience lethargy, pain, ataxia, and circling movements. Convulsions and increased body temperature are observed, mainly in the ophthalmic form of GME, coupled with one- or two-sided blindness and in combination with a reduced pupillary reaction to light.

In some cases, hyperesthesia (strong sensitivity of the neck and back of the head) can be noted, and in most animals the clinical picture manifests itself in the form of central vestibular syndrome.

Necrotizing (NEM) (necrotizing meningoencephalomyelitis) or in early descriptions – encephalitis of pugs.

This disease was first described as a “personal” disease in pugs in the early 20s of the last century. Upon further research, it was found that NEM also affects other dogs, but miniature (pocket) pets are more often affected.

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NME is characterized by the fact that it affects the white and gray matter of the brain, but misses the spinal cord. Sometimes myelomalacia develops. Clinical signs appear suddenly, predominantly in puppies (but range from 6 months to 7 years) - seizures, paresis, decreased proprioception and lethargy.

Necrotizing encephalitis was first described relatively recently, at the end of the last century in the Yorkshire terrier. It was later established that NE also affects other breeds of decorative dogs, and is sometimes found in French bulldogs. The age of animals affected by NE ranges from 4 months to 5(10) years.

Clinical manifestations

The clinical picture is generally characteristic of all types of MEM - convulsions, ataxia, lethargy and pain (in some cases in the neck), circular movements, paresis and paralysis are possible.

Diagnostic procedures are possible only in well-equipped, modern clinics, such as DobroVet VC.

MRI is mandatory, with T1, T2 and FLAIR modes. Analysis of the cerebrospinal fluid shows the presence of lymphocytes (more than 500 ml), but this analysis can be carried out no earlier than 2 weeks if corticosteroids were used.

A third of patients are diagnosed with mixed lymphocytic pleocytosis, but mixed pleocytosis plus eosinophilic granulocytes is diagnosed in almost two thirds of all patients.

Treatment of animals with MEM is complex; it involves the use of strong drugs and only under the supervision of the treating veterinary specialist, since many drugs have serious side effects. Therefore, the animal is placed in a hospital under 24-hour supervision.

Veterinary

Among the “new” pathologies, MEM (meningoencephalomyelitis) is especially distinguished, which most often occurs in decorative breeds of dogs, sometimes in large ones and even in cats.

Symptoms of the disease

It is difficult to diagnose encephalitis in a dog when symptoms occur in the later stages. As the disease progresses and foci of necrosis form, you can notice the first signs of illness in your pet.

The following symptoms may indicate the presence of inflammatory processes in the animal’s brain:

• limb spasms;
• paralysis;
• increased body temperature;
• weakness;
• apathetic state;
• refusal of food;
• vomit;
• bloody diarrhea;
• impaired pupil reflexes;
• blindness;
• disturbances of consciousness;
• epileptic seizures;
• change in urine color to brown, dark brown or green;
• walking disorders;
• In small breeds of dogs, tremors may be observed with encephalitis.

In each individual case, some of the symptoms described above are present, since the manifestations of the disease depend on the root cause of the disease. The absence of clear signs of encephalitis makes diagnosis difficult, but an experienced veterinarian will accurately identify the problem. Therefore, visiting a doctor immediately after the first symptoms of illness appear in your pet plays a huge role in the further healing of the animal.

Necrotizing meningoencephalitis in dogs

Necrotizing meningoencephalitis (NME) is an inflammatory disease of the central nervous system (CNS) that occurs more commonly in young and typically miniature breed dogs. Necrotizing meningoencephalitis has been described in many small dog breeds, including the pug, maltese, and chihuahua.

With meningoencephalitis, inflammation of the meninges (meningitis) and the brain itself (encephalitis) occurs. The etiology of necrotizing meningoencephalitis is unknown, just as the etiology of granulomatous meningoencephalitis is unknown, and there is much in common between these diseases. An autoimmune cause of the disease is also suspected and considered. In addition, in dogs, meningoencephalitis has been associated with various infectious agents, including bacteria, fungi, protozoa, rickettsia, parasites and viruses. There are a number of reports in the literature of similar non-suppurative idiopathic meningoencephalitis, including cases of necrotizing meningoencephalitis (NME) in a number of breeds, including the Maltese, pug, Shih Tzu, Chihuahua, Papillon and Pekingese.

Without supportive aggressive immunosuppressive treatment, necrotizing meningoencephalitis is quite rapidly fatal and often fatal, even despite adequate therapy. Similar to granulomatous menigoencephalitis, it is difficult to diagnose and only histological analysis of the affected tissue can definitively make a diagnosis.

Clinical picture of necrotizing meningoencephalitis in the Yorkshire terrier and possibilities of supportive treatment

NME is characterized by multiple, often asymmetric, necrotizing, nonexudative meningoencephalitis and is mainly localized in the cortex and subcortical white matter of the brain. Necrotizing menigoencephalitis is identified as a separate nosology. The most commonly affected animals are: Yorkshire Terrier, French Bulldog, Spitz, Miniature Pinscher, and Pekingese. Unlike granulomatous meningoencephalitis, when the accumulation of cells in the affected areas prevails, in necrotizing meningoencephalitis the processes of alteration (destruction) prevail. These changes can be detected using research methods such as MRI and CT. Intense inflammation and softening of areas are detected, usually limited to the subcortical white matter of the brain and most often in the region of the brain stem and cerebellum.

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For maintenance treatment, immunosuppressive therapy is used. Treatment is generally similar to granulomatous meningoencephalomyelitis.

NME is characterized by multiple, often asymmetric, necrotizing, nonexudative meningoencephalitis and is mainly localized in the cortex and subcortical white matter of the brain. Necrotizing menigoencephalitis is identified as a separate nosology. The most commonly affected animals are: Yorkshire Terrier, French Bulldog, Spitz, Miniature Pinscher, and Pekingese. Unlike granulomatous meningoencephalitis, when the accumulation of cells in the affected areas prevails, in necrotizing meningoencephalitis the processes of alteration (destruction) prevail. These changes can be detected using research methods such as MRI and CT. Intense inflammation and softening of areas are detected, usually limited to the subcortical white matter of the brain and most often in the region of the brain stem and cerebellum.

Infection from a tick bite

Tick-borne encephalitis in dogs is considered one of the most severe types of the disease. An animal becomes infected as a result of a dog tick bite. An outbreak of this viral disease occurs in the spring and summer.

Infection of the animal’s body occurs within 7 minutes after the dog is bitten by an encephalitis tick. In this case, veterinary care must be provided to the pet as quickly as possible. Lack of treatment in the first 2-5 days after the bite ends in the death of the pet, so contacting a specialist should be done immediately. The incubation period for tick-borne encephalitis is 3.5 weeks.

The main symptom of tick-borne encephalitis is a neurological crisis, which occurs as a result of damage to the central nervous system by the virus. The disease occurs with the following symptoms:

• paralysis of limbs;
• convulsions;
• a sharp increase in the animal’s body temperature;
• motor disorders;
• apathetic or aggressive mood;
• increased sensitivity to pain in the head and neck area.

If left untreated, paralysis of the muscles of the eyes and face occurs.

Emergency actions if a dog is bitten by a tick

First of all, carefully remove the tick using any known methods: tweezers, a loop of thread, or a hot needle. To facilitate removal, drop oil onto the parasite. It is imperative to remove the entire parasite and ensure that it has a head, otherwise the remains of the tick will cause severe symptoms of intoxication.

The next step is to visit a doctor. The veterinarian, taking into account the dog’s condition, will prescribe treatment and certain laboratory tests to confirm the diagnosis.

Diagnostics

The lack of a clear list of symptoms of encephalitis makes it much more difficult to diagnose, so a simple examination and general tests will not be enough for the veterinarian. As a rule, a series of laboratory tests using special medical equipment is prescribed. Unfortunately, not all veterinary clinics have enough capabilities for quick diagnosis and high-quality treatment of pets.

Diagnosis of encephalitis is carried out using the following methods:

• X-ray examination of the head;
• contrast radiography;
• MRI;
• cerebrospinal fluid analysis;
• Ultrasound diagnostics;
• EEG of the head;
• hematological blood examination;
• bacteriological analysis of cerebrospinal fluid.

If it is not possible to carry out all of the above examinations, you should not refuse the help of a veterinarian.

If encephalitis is suspected in dog breeds that are predisposed to this disease, the examination is carried out more thoroughly. High-quality diagnostics allows us to identify not only the presence of the disease, but also possible disorders that arise as complications.

What does an encephalitis tick look like?

If you find a tick on your dog, you need to know exactly what action to take next. The encephalitis tick is no different in appearance from other “bloodsuckers”. It is most often found in an enlarged state. And in order to be completely satiated, the tick needs 2-10 hours.

Tick ​​on a dog

If such a parasite is found in a dog's fur, you must try to remove the tick. This must be done carefully, trying not to leave its proboscis under the skin (which may contain an infection). To do this, use a syringe, a special device or tweezers, with which you need to grab the tick and carefully twist it out of the skin with a rotating motion. Next, be sure to disinfect the wound (with alcohol, brilliant green, etc.).

Important!

There is no need to throw away the tick. If you suspect a possible infection, it should be placed in a glass jar and taken to the laboratory at the veterinary clinic to be tested and find out whether it was infected with encephalitis.

Experts do not recommend using oil or kerosene to pull out a tick in order to block the respiratory system, since their action can cause the “bloodsucker” to quickly expel the contents of his stomach along with the infection out of fear.

Treatment

It is necessary to treat encephalitis taking into account the degree of damage to brain tissue. The first appointments of a veterinarian are aimed at getting rid of the cause that caused the disease, as well as the identified complications and ailments that appeared against the background of the inflammatory process. If possible, measures are taken to reduce swelling of the brain and spinal cord. As a rule, when encephalitis is diagnosed, complex treatment is prescribed, which includes the following methods:

• Drugs that remove excess fluid to eliminate cerebral edema. In most cases, mannitol or glucose is prescribed for this. The use of magnesium sulfate is not recommended, because when using this product there is a high risk of developing a heart attack with subsequent death of the pet.
• Drugs that stimulate the nervous system will help restore lost reactions and sensations.
• Acupuncture, massages and electric shock are prescribed in advanced stages of the disease.
• Drugs aimed at eliminating the causative agent of encephalitis (antifungal or antibacterial agents).
• Topical preparations to eliminate skin irritations;
• Hormone injections if necessary;
• Vitamin and mineral supplements to improve immunity.

Treatment is carried out under the supervision of a veterinarian; the use of drugs without prior consultation with a doctor is not allowed, as there is a risk of further harm to the pet.

Complications and prognosis

Encephalitis is dangerous because it can cause irreversible changes in the body, which means that treatment does not always give the expected result. Therefore, the functionality of individual organs and systems works only partially. After treatment, the dog’s immunity is significantly reduced and there is a high risk of re-developing encephalitis or other diseases.

After treatment, it is recommended to cleanse the pet’s circulatory system: hemosorption and plasmapheresis. These manipulations help improve the animal’s condition and eliminate the consequences of the disease.

The course of the disease depending on the virus

Encephalitis is dangerous regardless of which virus has entered the pet’s body. Different genotypes express themselves differently.

Phases of development of the European virus

The European virus is characterized by a two-phase course of the disease. At first, the following symptoms are observed:

• fever;
• refusal to eat;
• spasms;
• muscle pain;
• gagging.

Lasts 2-4 days. Then there is a period of remission for about a week. When the second phase occurs, in addition to the symptoms of encephalitis, signs of meningitis may be observed.

Far Eastern virus: course of the disease and consequences for the dog

The prognosis for infection with this virus is unfavorable. It provokes the following changes:

• meningitis;
• meningoencephalitis;
• focal lesion.

The risk of death is incredibly high. Paralysis of the respiratory muscles and forelimbs is noted.

Meningoencephalitic form

The following symptoms are characteristic of this pathology:

• epilepsy attacks;
• paresis of the head muscles;
• problems with swallowing;
• respiratory failure;
• weakness in muscle tissue.

Focal encephalitis

In the focal form of the disease the following are observed:

• 
  convulsive syndrome;

• muscular dystrophy;
• severe neurological disorders.

The clinical picture is in many ways similar to the symptoms of diseases of the nervous system.

Prevention

In order to prevent the development of the disease in your pet, you should take care of protection against ticks. For this purpose, special sprays, collars, vaccinations and drops on the withers are used. It is also necessary to minimize the risk of head injury to the animal. After walks, you should inspect your pet’s body and its ear canals for ticks or foreign objects.

Preventive examinations of dogs with a predisposition to encephalitis will help identify the disease in the early stages and receive effective treatment. In addition, it is important to remember to maintain the animal’s immunity and promptly eliminate any problems with its health.

How to treat an animal

Therapy is carried out comprehensively. Tactics largely depend on the condition of the pet and the form of pathology.

Choice of antiviral drugs

To destroy the virus, powerful antibiotics are prescribed:

• Co-Trimoxazole;
• Isoniazid;
• Rifampicin;
• Pefloxacin.

Medicines have a strong toxic effect, so your veterinarian may prescribe less aggressive medications:

• Pefloxacin;
• Tienam;
• Ceftazidime;
• Cefepime.

Symptomatic therapy

Symptomatic treatment includes:

• medications that relieve pain and reduce body temperature;
• drugs that help reduce intracranial pressure (Mannitol, Diacarb);
• corticosteroids to eliminate symptoms of neurological disorders (Methylprednisolone).

What vitamins are needed during this period?

Vitamins are prescribed along with basic medications.

The pet suffers from a deficiency of vitamins C and group B.

When does the body detoxify?

In cases of severe fever and the development of the meningeal form of pathology, detoxification is indicated. The animal is injected with a buffer solution and saline solution. The pH level in the blood and the state of water-salt balance are taken into account.

Relief of bulbar disorders

Due to the development of the pathological process, bulbar disorders are possible, manifested by impaired breathing and swallowing functions. In order to relieve clinical manifestations, oxygen is administered to the animal using a nasal catheter.

The following medications may also be prescribed:

• Sodium hydroxybutyrate;
• Cytochrome;
• Seduxen.

What can cause the disease?

The inflammatory nature of this disease can be caused by both infection entering the animal’s body and the presence of an infectious-allergic reaction. Causative agents of encephalitis:

• specific infections: parvovirus, rabies or pseudorabies, viral hepatitis or plague, leptospirosis, herpes or adenovirus;
• mycoses: histoplasmosis, aspergillosis, blastomycosis, coccidioidomycosis, phaeohyphomycosis, cryptococcosis;
• migration of parasites: Ancylostoma caninum, Dirofilaria immitis, cysticercosis, Toxocara canis, cuterebriasis;
• untreated inflammatory processes in the dog’s inner ear;
• migration of foreign bodies: plant awn (a pointed piece of a plant, for example, a spikelet tendril, which enters the body, moves in it and provokes inflammatory reactions);
• traumatic head injuries.

This disease is often called tick-borne encephalitis, but it is worth noting that very few cases of animal infection by Ixodes ricinus (dog tick) have been reported in veterinary practice. This disease is often confused with borreliosis or piroplasmosis. If the disease is the result of injury, purulent otitis, sepsis or a complication of any other process in the animal’s body, then it is called a secondary inflammatory process. Otherwise – primary encephalitis.

Forecasts

The consequences of encephalitis are irreversible:

• complete or partial paralysis;
• memory loss: the pet stops recognizing its owner and begins to attack;
• death.

The prognosis largely depends on what form of the disease manifested itself in the animal.

For bacterial and fungal encephalitis

If therapy was started in a timely manner and all veterinarian recommendations were strictly followed, the outcome will be favorable.

If a viral brain infection occurs

It is impossible to say unequivocally what the prognosis will be if the virus affects the brain. The outcome directly depends on the general condition of the pet and the genotype of the virus.

Autoimmune lesion

With this course of the disease, the prognosis depends on the type of autoimmune lesion. Taking this into account, the length and quality of life of the pet will be different.

Consequences and complications

The consequences of encephalitis are, as a rule, diseases directly related to weakening and damage to the main systems of the body. First of all, the kidneys and brain are affected by this disease. Thus, with a high degree of probability, the dog may develop, for example, kidney failure. The severity of the disease may vary - if renal failure has developed thoroughly, then the removal of fluids from the body will be difficult (especially in the complete absence of urine). Helping a dog with such complications will be both difficult and financially expensive. Dialysis can only help if the body is still producing urine.

From the information provided above, only one conclusion can be drawn - encephalitis must be treated in a timely manner and only under the supervision of a doctor. This will not only save you time, effort, nerves and money, but can also save your pet’s life.

Some of the most effective measures to eliminate the consequences of encephalitis are plasmapheresis and hemosorption, the so-called cleansing of the circulatory system. A day after such operations, the animal’s health condition noticeably improves.

Eyes

One of the main features of the breed is rather large eyes and a sluggish look.

icon-arrow-circle-right Diseases that are not very dangerous, but occur quite often, are inflammations and infections that occur when the corneas of a dog’s eyes are injured. The disease can appear when injected with grass, or when the eyes are clogged with sand or dust particles. After injury, a small ulcer forms, begins to grow and develops into an inflammatory process. There is no prevention for this disease.

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If injuries are detected, you should not think that they will disappear on their own; waiting often leads to the dog’s eye falling out. If you see damage, immediately visit your veterinarian.

icon-arrow-circle-right The owners of this breed of dog are also very worried about such a disease as eyeball prolapse. This situation can happen due to a blow to the pug's eye, or if he is bitten by an insect. It’s a pretty scary picture when a dog’s eye actually hangs by a thread, but this happens quite rarely. In such a situation, it is prohibited to perform any actions on your own; you can make things even worse, and then intraocular pressure will form.

icon-arrow-circle-right It is necessary to apply a patch to the eye and immediately go to the veterinarian.

icon-arrow-circle-right Pugs also have an eye disease called glaucoma, which is formed from the incorrect structure of the eye, which disrupts the outflow of blood from it. As a result: intraocular pressure increases, the eyes swell and turn red. These troubles can be avoided if you start treatment immediately at the first symptoms of the disease:

• fear of light;
• the edges of the eyes are constantly red
• in the evening the eyes become swollen;
• the pug develops a headache, the pet becomes lethargic and begins to rest its head against the wall;
• The pug's eyes begin to water, a hazy look and a dilated pupil appear.

In all such situations, a veterinarian will help you, otherwise the dog may go blind.

Other diseases transmitted by ticks

A tick bite is dangerous because it is not immediately detected; during the first day, the infection enters the bloodstream and is transported throughout the body. As a result, diseases such as:

1. Piroplasmosis is a seasonal disease caused by ixodid tick bites. It is manifested by an increase in temperature to 41 degrees, apathy, urination with blood, and muscle weakness. The infection period lasts up to 2.5 weeks.
2. Chronic piroplasmosis - like the second stage of encephalitis, is observed in animals with strong immunity; the signs are not differentiated. The period of infection spreading throughout the body is prolonged. The clinical picture visually manifests itself after the pet’s immunity has weakened.
3. Ehrlichiosis is caused by the bite of a dog brown tick; clinical signs may appear 2 months after infection. On examination, hemorrhages on the mucous membranes are diagnosed.
4. Anaplasmosis – characterized by rapid weight loss in the pet and disruption of the digestive tract. When a tick bites, platelets are affected. Often the disease occurs in a chronic form, which leads to the onset of the disease and its difficult elimination.

By being sensitive to your pet, you can avoid many of the serious consequences of infectious diseases.

Encephalitis in dogs is a serious infectious disease that can lead to irreversible consequences in the pet’s health. It is important to follow preventive measures and not ignore the symptoms of deterioration in your pet’s health.