Encephalitis in Dogs

Hearing a Scary Diagnosis from the Veterinarian

Hearing a frightening word from the veterinarian can be overwhelming, especially when it’s hard to grasp what it means. Often, it immediately brings to mind the worst-case scenario: everything the vet just said might imply that your time with your beloved pet is limited. However, when it comes to a condition like encephalitis, there can be room for cautious optimism.

What is Encephalitis?

Encephalitis is classified as inflammation of the brain, which occurs when a dog’s immune system attacks its own brain tissue. While encephalitis can develop independently, it’s usually linked with other neurological diseases.

Inflammatory diseases of the brain and spinal cord, collectively known as the central nervous system, are among the most frequent causes of neurological conditions in dogs. Besides encephalitis, there’s myelitis, an inflammation of the spinal cord, and meningitis, inflammation of the brain’s protective fibrous layers. If all three areas are involved, the condition is called meningoencephalomyelitis. Encephalitis is often used as an umbrella term for inflammatory diseases of the central nervous system, since it primarily affects the brain.

Which Dogs Are Prone to Encephalitis?

Encephalitis is most common in certain breeds like Chihuahuas, Yorkshire Terriers, Maltese, Pugs, and German Shorthaired Pointers. While it can affect dogs of any age, it’s most frequently seen in young and middle-aged adult dogs.

Causes of Encephalitis in Dogs

Though encephalitis simply means brain inflammation, it’s not a standalone condition. Multiple factors may cause encephalitis, falling into two main categories: infectious causes and non-infectious (often immune-mediated or idiopathic) causes, with immune-mediated causes being more common in dogs.



The exact cause of immune-mediated encephalitis is still unclear, but some evidence suggests it may stem from an autoimmune disorder. Typically, a healthy dog’s immune system identifies and defends against harmful agents. However, in cases of autoimmune disease, this mechanism reverses, and the immune system begins attacking the dog’s own tissues. In encephalitis, the immune system targets the brain and its surrounding membranes (meninges).

Infectious Causes of Encephalitis

Several forms of immune-mediated encephalitis exist, with the most commonly diagnosed being Granulomatous Meningoencephalomyelitis (GME). This primary inflammatory condition often affects all three brain regions, meninges, and the spinal cord.

Less common infectious causes of encephalitis include bacterial infections (both aerobic and anaerobic), viruses such as distemper, rabies, and parvovirus, fungal infections like aspergillosis, histoplasmosis, and blastomycosis, as well as parasitic infections such as Rocky Mountain spotted fever and ehrlichiosis.

Research has identified a genetic predisposition for immune-mediated encephalitis in Pugs. A blood test can reveal this genetic defect, which doesn’t determine if the dog has the disease but identifies Pugs at higher risk. This test can help breeders identify at-risk Pugs before breeding. For cats, encephalitis is less common and is more often due to infections. Research continues on the causes and treatments of immune-mediated encephalitis.

Regardless of the cause, encephalitis is life-threatening and should be diagnosed and treated promptly.

Symptoms of Encephalitis

Symptoms depend on which part of the brain is affected. Common symptoms include:

• Fever
• Seizures
• Uneven pupil size
• Behavioral changes, such as depression
• Loss of balance
• Head tilt
• Facial paralysis
• Uncoordinated movements
• Decreased responsiveness
• Blindness
• Pain
• Tremors
• Altered consciousness

Symptoms of encephalitis may worsen as the disease progresses. Seizures, blindness, behavior changes, and mental depression are common when the forebrain (cerebrum) is affected. Loss of balance, coordination issues, head tilt, tremors, or facial paralysis are associated with brainstem involvement. Neurological abnormalities can occur in one part (focal) or multiple parts (multifocal) of the brain.

A full neurological examination is required to pinpoint the affected areas of the brain. In dogs with encephalitis, symptoms typically develop over days or weeks and may progress rapidly.

Diagnosing Encephalitis in Dogs

For diagnosis, you’ll need to provide the vet with detailed information on your dog’s symptoms, breed, age, health history, and any recent injuries. This helps the vet make an accurate diagnosis.

Given that other neurological diseases often mimic encephalitis symptoms, a full cycle of testing is usually necessary. Vets will conduct a thorough examination and perform blood chemistry, a complete blood count, and a urinalysis.

These tests can help detect possible infectious causes of brain inflammation. For instance, reduced white blood cell count may suggest a bacterial infection, while viral infections may lower lymphocyte levels.

Often, however, these tests aren’t enough for an encephalitis diagnosis. MRI or CT scans may be needed to assess brain structure and function, along with a spinal fluid (CSF) test to assess the severity of inflammation.

Treating Encephalitis in Dogs

Treatment for encephalitis should always involve a veterinarian, as home remedies are ineffective against this condition. A vet will focus on alleviating symptoms such as seizures or brain swelling to halt disease progression, which may require hospitalization for intensive care.



If bacterial infection is involved, treatment with broad-spectrum antibiotics may be necessary. However, since encephalitis in dogs is often autoimmune, treatments typically focus on reducing inflammation in the brain and suppressing the overactive immune response. Prednisolone is often used to reduce inflammation, but dogs on prednisolone alone often have a shorter survival period.

After initial treatment, your vet will schedule regular checkups to assess treatment effectiveness and your dog’s overall health. Monitor your dog’s response and report any changes to the vet. If vomiting or depression occurs, a specialized diet may be advised.

Long-term Prognosis

Although encephalitis can rapidly become life-threatening, the prognosis is often favorable with early diagnosis and active treatment. Prognosis varies based on factors like how long the dog has been ill, the affected brain areas, symptom severity, and response to treatment.

Many dogs respond well to treatment and can enjoy additional years with their families. With appropriate care, symptoms can improve within two to eight weeks.

In some cases, symptoms may recur after treatment ends, requiring additional or long-term therapy. If you suspect symptoms of encephalitis, consult a veterinarian for prompt diagnosis and treatment to help prolong your pet’s life.