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Granulomatous Meningoencephalomyelitis in Dogs

Granulomatous meningoencephalomyelitis (GME) is an inflammatory disease of the central nervous system (CNS) that leads to the formation of granuloma(s) --  a ball-like collection of immune cells formed when the immune system tries to wall off foreign substances -- which can be localized, diffused, or involving multiple locations, such as the brain, spinal cord and surrounding membranes (meninges).

This disease is the most well recognized and accepted CNS inflammatory disorder in dogs. However, dogs between the ages of 6 months and 10 years are most commonly affected with GME. And although both sexes can be affected, there is a slightly higher prevalence in females.

Symptoms and Types

The symptoms depend on the form of disease and its location. For example, the ocular form of GME will affect the eye region, while multifocal GME will affect the brain or brain and spinal cord, and focal GME will focus singly on either the brain or spinal cord. Common symptoms associated with GME include:

• Blindness
• Drowsiness
• Circling
• Seizures
• Behavioral changes
• Weakness of hind limbs (parapresis)
• Weakness of all four limbs (tetraparesis)
• Constant head pressing against objects

Causes

The exact cause of GME is currently unknown.

Diagnosis

You will need to give a thorough history of your dog’s health to your veterinarian, including the onset and nature of the symptoms. He or she will then perform a complete physical examination as well as a complete blood count, biochemistry profile, and urinalysis -- the results of which are typically within normal ranges unless an infection is present. In those cases, the white blood cell count will be abnormally elevated.

The preferred method for diagnosis, however, is an MRI (Magnetic Resonance Imaging) scan, which will reveal single, multiple, or well circumscribed lesions within the nervous system. Your veterinarian may also take a sample of cerebrospinal fluid, a nourishing fluid that circulates around the brain and spinal cord. Though not a good test to confirm a diagnosis of GME, it can confirm inflammation associated with the disease. 

In addition, conducting a brain biopsy can help confirm GME, but it is rarely done due to the dangers involved with removing a small sample of brain tissue.