Encephalitis in Cats

Midsection Of Veterinarian Holding Cat In Hospital

Arne Trautmann / EyeEm / Getty Images


Encephalitis in cats is one of the most commonly seen neurological problems.

What Is Encephalitis?

Literally meaning inflammation of the brain, encephalitis is a life-threatening condition that can occur by itself in conjunction with other neurological illnesses such as myelitis (inflammation of the spinal cord) and meningitis (inflammation of the meninges, which are the membranes that cover your cat's brain and spinal cord).

Symptoms of Encephalitis in Cats

Encephalitis can lead to a whole host of symptoms. Most of them are considered to be classical for a neurological disease process. If you see any of the symptoms listed below, seek veterinary medical care immediately.


Causes of Encephalitis in Cats

Encephalitis, unfortunately, can have a multitude of causes. Some of the most common are outlined below.

Viral Infections

A viral infection, such as Feline Immunodeficiency Syndrome (FIV), Feline Infectious Peritonitis (FIP), or even rabies can cause encephalitis. Most public health departments require all cats, regardless of indoor/outdoor status, to be vaccinated for rabies. There is a vaccine for FIV but most vets don't vaccinate cats for it. This is partly because the risk of contracting it is low, as the primary mode of transmission is through bite wounds. It is also partly because a cat that's vaccinated for FIV will subsequently test positive despite not actually having the illness.

FIP is caused by a feline-specific virus. Similar to FIV, there is a vaccine that has been developed for FIP but, just like FIV, it is not normally utilized. This is because studies have shown that the efficacy of this vaccine is variable, if effective at all. As such, the American Association of Feline Practitioners does not currently recommend it as a core vaccine for cats.

Bacterial Infections

Bacterial infections, whether they be aerobic (one that requires oxygen) or anaerobic (one that can thrive without oxygen), can cause encephalitis in your cat.

Fungal Infections

Fungal infections, such as those caused by Cryptococcus neoformans and Blastomyces dermatididis, can also cause encephalitis.

Parasitic Infections

Things like toxoplasmosis, caused by the protozoal parasite Toxoplasma gondii, may lead to encephalitis.

Other Causes

Your cat doesn't need to contract anything infectious to develop encephalitis, though. Other causes include immune-mediated disorders as well as idiopathic (meaning a cause is never pinpointed) encephalitis.

Diagnosing Encephalitis in Cats

You should always take your cat to the vet if they are displaying concerning neurological signs. A full physical examination will be conducted, including a full neurological exam.

Once done examining your cat, your vet will likely want to run blood work and a urinalysis. Depending on what's causing your cat's suspected encephalitis, their blood work will show different values. A bacterial infection will cause an increase in white blood cells, while a viral infection may cause a decrease in a specific type of white blood cell called a lymphocyte.

Imaging can also be done to give your vet an inside look at your cat's brain and spinal cord. X-rays may show lung involvement, but to better assess your cat's neural system your vet will need to see advanced images, such as an MRI or CT scan. These can give your vet a more detailed look at the extent of your cat's encephalitis and what part (or parts) of the brain is involved.

Finally, your vet may want to collect a sample of your cat's cerebrospinal fluid, as culturing it can identify any infectious agent causing your cat's symptoms.


Your vet's immediate concern will be to decrease the swelling in your cat's brain and to stop any seizures that your cat may be suffering from. They will prescribe medications to specifically help with these.

If a causative agent is identified, your vet will prescribe medications to treat that as well. This can include antibiotics or antifungals. There are antiviral medications for cats available but they come with their own set of risks. Your vet will be able to discern whether they would be an appropriate treatment option for your cat or not.

If your cat's symptoms are severe, they may require hospitalization for around-the-clock care. This can include intravenous antibiotics and supportive care such as intravenous fluids.

Once treatment is started, you may start to see improvement in your cat's symptoms over the course of weeks to months. The prognosis and speed of recovery will depend on what's causing your cat's encephalitis and the severity of their case. Your vet will also want to see your cat for routine check-ups to closely monitor their recovery.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Article Sources
The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Meningitis and Encephalitis in Cats. Merck Veterinary Manual.

  2. Feline Vaccines: Benefits and Risks. Cornell University College of Veterinary Medicine.

  3. Meningitis, Encephalitis, and Encephalomyelitis in Animals. Merck Veterinary Manual.