Brain Tissue Inflammation and Death (Breed Specific) in Dogs

Necrotizing encephalitis is a severe condition that can appear acutely or take on a chronic form, gradually worsening over a period of approximately six months. Sadly, most canines die or are euthanized within this period of time. Studies show that dogs with this type of brain inflammation are shown at autopsy to have lesions in either the forebrain or the brainstem, and sometimes both. Other evidence seen is fluid accumulation as well as cyst formation. There is no sex predilection though females show a slightly higher incidence of the disease. The condition affects predominantly small breed dogs and there is a suspected genetic component.

When brain tissue becomes inflamed it is called encephalitis. Necrotizing encephalitis occurs when the inflammation in the brain is accompanied by tissue death. This is a progressive treatment with no known cure and typically results in eventual euthanasia of the dog.

Symptoms will depend on the location of the lesions and inflammation in the brain.

Forebrain

• Changes in mental state
• Changes in behavior
• Seizures
• Circling
• Blindness
• Head tilt is sometimes seen

Brainstem

• Difficulty walking
• Cranial nerve deficits, of which the list is extensive

Types

Necrotizing Meningoencephalitis

• Age of onset is 6 months to 7 years with the average being 2.5 years
• Pugs are the breed most affected
• Breeds also predisposed : Papillon, Shih Tzu, Coton de Tulear, Boston Terrier, Pekinese, Maltese and Chihuahua

Necrotizing Encephalitis

• Age of onset is usually 4 months to 10 years with the average age being 4.5 years
• Breeds affected are the Yorkshire Terrier and French Bulldog

It should be noted that there has been documentation of brain tissue inflammation and death in the Greyhound, Labrador Retriever and Miniature Pinscher. The two types  of necrotizing encephalitis are classified separately because of distinct differences between the location and appearance of lesions found postmortem.

There are many causes for brain inflammation in dogs, but a specific cause for the distinct necrosis (death of tissue) is unknown. Researchers suspect autoimmune or immune regulatory or dysregulatory implications, though proof has not yet been found. Genetics are thought to be of strong consideration in cases of brain tissue inflammation and death.

Your veterinarian may see abnormal neurological signs in your pet upon physical examination. Neck pain is sometimes found to be present, even though we were not aware that our dog was uncomfortable. Canines have a way of disguising their pain, and due to their lovable, kind nature, they often take a stoic approach to illness. The veterinary team will also proceed with an analysis of the blood, a most important step to ruling out possible causes for your pet’s behavior and symptoms.

Other illness that can display similar signs to brain inflammation can be metabolic disturbances, nutritional deficiency, toxicity, the presence of a tumor, and infection such as a fungal or bacterial invasion.

Tests that may show a more definitive diagnosis are the CT scan or MRI (especially of a contrast nature, which will define lesions), and an analysis of the cerebrospinal fluid (which can point to inflammation, but not the cause).

Treatment is aimed at comfort of life, not a cure. Long-term, high-dose corticosteroid therapy is the usual course; the aim is to suppress the immune system. High doses of prednisone, for example, are often given but this treatment is not without side effect. Antiseizure medication may be prescribed also. As a pet owner you must be aware that  certain medications of this type are given for the duration of the pet’s life. 

Reality must be faced when a pet is given the diagnosis of brain tissue inflammation. Dogs with this condition usually survive on average six months after symptoms become apparent. Rarely, there have been canines that have lived for a few years.

The monitoring of your furry family member will be important during treatment. There could be side effects to the medicinal therapy such as weight gain, gastrointestinal ulcers, and pancreatitis. Your veterinarian will advise on the frequency of follow-up visits, depending on the condition of your pet at diagnosis and how well he responds to treatment. As always, keep in close contact with your veterinary caregiver and do not hesitate to communicate with her if you have questions or concerns.