Encephalitis: Brain Inflammation in Dogs

Encephalitis in Dogs

The term encephalitis refers to an inflammation of the brain. However, it also may be accompanied by the inflammation of spinal cord (myelitis), and/or the inflammation of the meninges (meningitis), membranes which cover the brain and spinal cord.

German short-haired pointers, Maltese, and Yorkshire terriers are all found to be predisposed to encephalitis.

Symptoms of Encephalitis

Although symptoms may vary depending on the portion of brain affected, they typically appear suddenly and are rapidly progressive. Such symptoms include:

• Fever

• Seizures

• Behavioral changes (e.g., depression)

• Decreased responsiveness

• Head tilt to either side

• Paralysis of face

• Uncoordinated movements or circling

• Unequal size of pupils (anisocoria)

• Smaller sized pinpoint pupils

• Decreased consciousness, which may worsen as disease progresses

Causes of Encephalitis

• Idiopathic (unknown cause)

• Immune-mediated disorders

• Post-vaccination complications

• Viral infections (e.g., canine distemper, rabies, parvovirus)

• Bacterial infections (anaerobic and aerobic)

• Fungal infections (e.g., aspergillosis, histoplasmosis, blastomycosis)

• Parasitic infections (e.g., Rocky Mountain spotted fever, ehrlichiosis)

• Foreign bodies

Diagnosis of Encephalitis

You will need to give your veterinarian a thorough history of your dog’s health, including the onset and nature of the symptoms, and possible incidents that might have precipitated the unusual behaviors or complications. Your veterinarian may then perform a complete physical examination as well as a biochemistry profile, urinalysis, and complete blood count (the results of which will depend on the underlying cause of the encephalitis).

If your dog has an infection, the complete blood count may show an increased number of white blood cells. Viral infections, meanwhile, may decrease the number of lymphocytes, a type of white cells (also known as lymphopenia). And abnormal reduction in platelets (small cells used in blood clotting) is a good indicator of thrombocytopenia.

To confirm lung involvement and related complications, your veterinarian may require chest X-rays, while MRIs and CT-scans are used to evaluate the brain involvement in detail. Your veterinarian may also collect a sample of cerebrospinal fluid (CSF), which is then sent to a laboratory for cultures. This is necessary for definitive diagnosis and to determine the severity of the problem. If culture assays are unsuccessful, a brain tissue sample may be necessary to confirm the diagnosis, but this is an expensive procedure.

Treatment of Encephalitis

Your veterinarian will focus on reducing the severity of the symptoms, such as brain edema and seizures, and halt the progression of the disease. Severe forms of encephalitis require immediate hospitalization and intensive care. For instance, those suspected of having bacterial infections will be given broad spectrum antibiotics, which can reach the brain and spinal cord.

Living and Management

With proper treatment and care, symptoms gradually improve within two to eight weeks; however, the overall prognosis depends on the underlying cause of the condition. For example, in some dogs, symptoms may reappear once treatment is discontinued. In such instances, a second round of treatment (or long-term treatment) may be required to save the dog's life.

Your veterinarian will schedule regular follow-up exams to evaluate the effectiveness of the treatment and the dog's state of health. Your vet may even recommend a new diet for the dog, especially if it is frequently vomiting or severely depressed.

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Stomach Flu with Bloody Diarrhea in Dogs

Hemorrhagic gastroenteritis is identified by blood in the vomit and/or stool, often due to a food borne illness. Because it is a serious disorder that can be potentially fatal, immediate veterinary care is required.

Symptoms

Continuous vomiting and/or diarrhea are the most common symptoms.

Other symptoms include:

• Lethargy

• Listlessness

• Anorexia

• Weight loss

• Fluid loss

• Electrolyte imbalance

• Dehydration

• Hemoconcentration

• Hypovolemic shock

Causes

Infectious gastroenteritis is caused by pathogens (infectious agents). Some of the pathogens most commonly associated with infectious gastroenteritis include:

• Bacteria (e.g., Campylobacter, Salmonella, E. coli, Clostridia)

• Virus (e.g., Parvovirus, Canine distemper)

• Fungi (e.g., Aspergillus, Penicillium, Fusarium)

• Parasites (e.g., Roundworms, Hookworms, Tapeworms, Whipworms, Coccidia)

E. coli, Salmonella and Corynebacterium are the most significant intestinal pathogens because they can be passed from animal to human or vice versa. Salmonella infections are also important due to the association with reproductive disorders.

Sudden dietary changes and/or dietary toxins may cause irritation and/or affect the immune system. Eosinophilic gastroenteritis, a chronic form of the illness, has been associated with allergens in dog foods. Gastroenteritis may be also observed due to irritation caused by stress, toxins, physical obstruction, ulcers, and abdominal disorders.

Gastroenteritis is not specific to any breed or gender, however, small breed dogs are more prone to infectious gastroenteritis.

Diagnosis

It may be difficult to identify the cause of gastroenteritis. Therefore, invasive diagnostic procedures may be required if routine diagnostic procedures are not successful.

A brief outline of diagnostic procedures:

Medical history:

• Physical obstruction, tumors, ulcers, intestinal blockage, etc.

• Information about the severity, progression and magnitude of the vomiting and diarrhea

• The vaccination record may help in ruling out a parvoviral infection

Physical observations:

• A skin test to determine the presence and extent of dehydration

• An abdominal palpation to check abdominal pain and/or abdominal obstruction

• An examination of mucus membranes to determine hemorrhagic losses

• Cardiovascular function provides information on dehydration and/or blood loss

• Visual observation of the vomit and/or stool to determine if there is blood present

Routine blood/biochemical tests:

• Packed cell volume (hematocrit) data to confirm hemorrhagic gastroenteritis

• Biochemical tests (i.e., liver, kidney, blood protein, and blood sugar)

Fecal study:

• Cultural assays to identify any potential microbiological or parasitic organisms

Radiographs/endoscopy:

• To locate any potential physical obstruction, tumor, ulcer, intestinal blockage, etc.

Treatment

In most of the cases, dogs recover and respond very well. The course of treatment, however, is dependent on the underlying cause of the condition. A brief outline of treatment is given below:

• Fluid and electrolyte therapies are important, especially in cases of hemorrhagic gastroenteritis.

• Antibiotic therapy may be restricted to animals with systemic infections.

• Corticosteroid therapy is useful in cases of shock. Usually hypovolemic shock develops due to dehydration.

• Dog medications that soothe the intestine and bind noxious agents can also be used in supportive therapy.

• Parasitic infections are treated with anthelmintics.

• Physical obstruction, ulcers and tumors may need surgical treatment.

Living and Management

An improved diet may reduce intestinal infections and other gastrointestinal disorders. The main priority should be to provide healing time for the dog's inflamed intestinal area. Thus, food and water should not be given for at least a period of 24 hours to rest the intestine. Then, provide a bland diet for three to seven days, followed by a gradual return to the dog's normal diet.

Often dietary irritants (especially protein) may lead to a recurrence of the problem. In these cases, a special hypoallergenic medical diet may be required.

Prevention

Some veterinarians have recently emphasized the importance of restoring intestinal microflora through food additives (e.g., probiotics, prebiotics, and synbiotics) in order to prevent the infection from recurring.

If dog owners are using homemade diets, the ideal micro- and macro-nutrient profile, along with optimum energy density, must be the focus of formulation. These diets provide highly digestible nutrients, less fats and restricted osmolarity. Consult your veterinarian for a proper, well-balanced diet for your dog.

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