Like humans, dogs can develop autoimmune encephalitis, and it’s common - mostly affecting smaller breeds and young adult dogs. Now scientists understand that humans and their canine companions share more in common with this disease: the same antibody testing applied to uncover specific forms of autoimmune encephalitis in humans appears to work similarly in dogs.
Encephalitis of any kind involves inflammation of the brain. When the condition is autoimmune-derived, that means that it’s the body’s own cells that are responsible for the inflammatory attack.
In humans, autoimmune encephalitis can lead to a variety of neurological and psychiatric symptoms, including impaired memory and cognition, psychosis, and loss of consciousness. The condition is generally treated with immunosuppressive therapy. Recent research links human autoimmune encephalitis with the immune system producing antibodies that target surface proteins of neurons. Scientists most often see antibodies targeted the glutamate receptor NMDA. Glutamate is a neurotransmitter that plays a role in learning and memory. The theory is that different types of autoimmune encephalitis are characterized by different surface protein targets of different neurons.
A dog with encephalitis may show the following signs:
Dogs expected of having encephalitis are tested for bacterial infections, but a biopsy of inflamed tissue is the only way to positively diagnose encephalitis. While a test can be done to indicate infection or not, the differentiation stops there Consequently, autoimmune forms of the disease are difficult to differentiate from other types of non-infectious encephalitis.
Autoimmune encephalitis is also difficult to treat. Currently the standard treatment is immunosuppression, although scientists believe that more likely than not, there is more than one type of autoimmune encephalitis. Like in humans, different forms of canine autoimmune encephalitis could vary based on which parts of the brain are being targeted.
In a new study, researchers conducted a clinical test in 32 dogs to screen for antibodies against six different neuronal surface targets identified in human cases of autoimmune encephalitis. Researchers applied the test on samples of cerebrospinal fluid of dogs diagnosed generally with encephalitis. Human and canine genes for the six neuronal surface targets are nearly identical, allowing the test to work for both species.
Of the 32 dogs tested, 19 had been diagnosed with inflammatory encephalitis. Of the 19, three dogs tested positive for antibodies to NMDA receptor target, and those three previously responded positively to immunosuppressive therapy.
What causes autoimmune encephalitis is still a mystery. In both humans and dogs, scientists are unsure about why it develops. But continuing research in this realm will open the doggy door for scientists to identify new antibody targets and define specific types of encephalitis like has been done for human cases.
More specific diagnosis could lead to more specific and all around more successful treatments for both dogs and humans. “Better categorization of the different forms of encephalitis might enable us to predict prognosis better and fine-tune treatment for different diseases,” explained Natasha Olby, Vet MB, PhD, MRCVS, DACVIM, corresponding author of the Journal of Veterinary Internal Medicine publication of the study’s findings.