Granulomatous Meningoencephalitis is a central nervous system disease that mostly affects dogs but can also be found in cats. An inflammatory disease that is known to be a form of meningoencephalitis, Granulomatous Meningoencephalitis is the second most common cause of inflammatory disease (next to encephalitis) of a dog’s central nervous system. Most common among young and middle aged female toy dogs, Granulomatous Meningoencephalitis progresses rapidly. Granulomatous Meningoencephalitis causes lesions in the white matter of the brain, specifically the cerebrum, brainstem, cerebellum, and spinal cord. The cause of Granulomatous Meningoencephalitis is not really known but it is not an infectious disease. Lesions of Granulomatous Meningoencephalitis are very similar to those caused by allergic meningoencephalitis and as such the disease is considered to be related to the immune system but could also be related to a dog’s response to an infectious substance.
Symptoms and Diagnosis
There are actually a number of different types of Granulomatous Meningoencephalitis which are related to subtly different symptoms. Disseminated Granulomatous Meningoencephalitis is associated with a build up of mononuclear cells and neutrophils around the blood vessels in the central nervous system. Meningitis, fever, neck pain, problems with coordination, nystagmus, seizures, and even depressions are all symptoms of disseminated Granulomatous Meningoencephalitis.
Alternatively, focal Granulomatous Meningoencephalitis is seen as a granuloma which is similar to a tumor. This “tumor” will normally be discovered in the cerebrum and associated symptoms can be acute or can take several months to develop depending on the severity and location of lesions.
Ocular Granulomatous Meningoencephalitis is the least common form of Granulomatous Meningoencephalitis and the most serious symptom is blindness (which is the result of optic neuritis). This form of Granulomatous Meningoencephalitis will affect both eyes. Blood vessels in the posterior portion of your pet`s eyes will show the same inflammation as cerebral cells. Because of this, ocular Granulomatous Meningoencephalitis is considered an extension of other forms of Granulomatous Meningoencephalitis. Other symptoms of this form of the disease include uveitis, retinal detachment, and glaucoma.
Diagnosis usually involves taking a cerebrospinal fluid (CSF) sample. In infected animals, the CSF will be very high in white blood cells and small (but mature) lymphocytes are the most common cells seen. Monocytes and neutrophils are also present. In some cases, a veterinarian will order some kind of scan like a CAT scan or an MRI to identify the presence of patchy, diffuse, and/or multifocal lesions.
There are several drugs that are used to treat Granulomatous Meningoencephalitis. Immunosuppressive drugs such as corticosteroids, azathioprine, and cylclophosphamide are amongst the most common drugs prescribed. Unfortunately, Granulomatous Meningoencephalitis is rarely, if ever, cured and most animals die within a few months of contracting the disease. Radiation therapy has been shown to offer the longest remission periods for focal Granulomatous Meningoencephalitis but chances are very small that the disease will not be fatal.