Brain Inflammation in Dogs

Encephalitis may occur in on its own or in conjunction with meningitis, which is recognized as the inflammation of the meninges, the meninges comprise as the membranes surrounding the brain and spinal cord, and/or myelitis, or the inflammation of the spinal cord itself. Encephalitis is most likely to be found in a young adult or adult dog and has a higher occurrence in the following breeds: Chihuahua, Yorkshire Terrier, Maltese, Pug, and German Short-Hair Pointers.

The symptoms of brain inflammation vary depending on the area of the brain affected. The onset of symptoms is sudden and progresses rapidly.

• Fever
• Pain
• Seizures
• Decreased pupil size
• Unequal pupil size
• Behavioral changes
• Depression
• Loss of balance
• Stumbling
• Blindness
• Decreased responsiveness
• Tilting head
• Face paralysis
• Uncoordinated movements
• Excessive circling

Infectious causes of brain inflammation are less common. They include bacteria, viruses (such as distemper, rabies, and parvovirus), fungal infections (such as aspergillosis, histoplasmosis, and blastomycosis), protozoa, rickettsia, complications of vaccines, and parasitic infections (such as Rocky Mountain spotted fever and ehrlichiosis).

Non-infectious causes of brain inflammation are the significantly more common. Some are idiopathic, meaning there is no known cause. All are autoimmune diseases, in which the immune system attacks itself.

Thorough reporting of the onset and extent of your dog’s symptoms will go a long way in aiding diagnosis. Be sure to include any recent injuries or incidents that may provide an alternative explanation for the changes in your dog’s behavior. The veterinarian and/or vet tech will complete an extremely thorough examination (physical), a chemical blood profile, complete blood count and urinalysis. The results of these tests will reveal possible infectious causes of brain inflammation, starting with a decreased white blood cell count pointing to infection.

Your dog’s brain structure and functioning will be evaluated with MRIs and CT scans, and cerebrospinal fluid may be sampled and sent to a laboratory for expert analysis. The imaging will reveal inflammation through the uncharacteristic density of white matter in your dog’s brain, as well as any asymmetry. These tests will typically be enough to elicit a positive diagnosis of brain inflammation; however, in some cases, analysis of a brain tissue sample may be the only way to confirm the diagnosis. Extracting a sample of brain tissue from your dog can be dangerous, and can only be performed by a specialist.

While treatment for brain inflammation may vary, initial focus will be on reducing the severity of the symptoms. Your dog may require hospitalization and intensive care for stabilization. In the case of brain inflammation caused by an infection, the underlying cause will be treated individually, often through individualized antibiotics. Treatment of the brain inflammation itself consists of medication designed to decrease inflammation and suppress the immune system, such as prednisone, cytosine arabinoside, cyclosporine, azathioprine, leflunomide, and procarbazine.

The veterinarian or specialist will help you to determine your dog’s individual prognosis because recovery will be directly correlated to the causation of the condition as well as severity through inflammation as established by the specialist or DVM. Treatment can control most dogs’ symptoms within a month or two; however, in many dogs, symptoms resume if medication is ceased. For this reason, your dog’s condition may necessitate long-term or lifelong management.

No matter your dog’s prognosis, you will need to return to the veterinarian for regular follow-up and monitoring of your dog’s condition and method of treatment.