Granulomatous Meningoencephalomyelitis (GME) in Dogs

Dog at vet
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The acronym GME stands for Granulomatous Meningoencephalomyelitis, a disease of the brain and spinal cord. 

The term granulomatous means a chronic inflammation that is characterized by several types of cells, including fibroblasts and immune cells. The term Meningoencephalomyelitis refers to an inflammation of the brain, spinal cord and the membranes that surround them (the meninges) that leads to the formation of granulomas—immune cells that collect in a ball shape which form when the immune system tries to block off foreign substances. These can be localized, diffused or involve multiple areas.

This disease can affect most breeds of dogs at any age; it is seen most commonly in middle-aged small breeds but can appear between six months and 10 years of age. Both sexes can be affected, but there is a slightly higher occurrence in females. At this time, the cause (etiology) is unknown.

Symptoms of GME in Dogs

Signs can vary from one dog to another, depending on the location of the granulomas. Focal GME mimics cancerous tumors and can be fatal within months; multifocal GME is an extremely aggressive disorder that can be fatal within a week. Ocular GME can blind a dog in one or both eyes, but may not progress to the point of actually being fatal. Depending on the type of GME, symptoms may include:

  • Ataxia (stumbling, wobbly gait)
  • Drowsiness
  • Blindness or vision problems
  • Behavior changes
  • Facial paralysis
  • A weakness of hind limbs or all four limbs (tetraparesis)
  • Depressed attitude
  • Head pressing against objects
  • Circling
  • Seizures

Sadly, most dogs affected by GME do not live long. In fact, except in unusual cases, GME can be fatal within a week to six months. There are, however, situations in which the lesions (granulomas) are limited; while they impact a dog's quality of life, they may not be lethal.

Causes of GME in Dogs

There is no widely accepted cause of GME. Research suggests that the causes may be immune-related, or may relate in some way to infectious disease.

Diagnosing GME

Your vet will ask you to provide a history of your dog's health including a description of his symptoms and when they began. A physical exam will follow along with a blood count, biochemistry profile and urinalysis.

The typical method for diagnosis is an MRI which can show lesions within the nervous system. Your vet may also take a sample of cerebrospinal fluid which circulates around the brain and spinal cord. While it's not a test that can confirm GME, it can detect inflammation associated with the disease.

Diagnosis is also made by ruling out other diseases since the only way to definitively diagnose this disease is by examining the brain or spinal cord tissue under a microscope. However, that's rarely done given the danger of removing a small sample of brain tissue.

Treatment and Prevention

If your dog has been diagnosed with GME, consider visiting a veterinary neurologist. These specialists have considerable experience with the disorder and may be able to offer more options than a typical veterinarian. In addition, they may be able to determine whether a misdiagnosis has occurred (there is no definitive medical test for GME).

Often, immediate hospitalization and intensive care are necessary for dogs with severe forms of GME and IV fluid is begun to counteract the body fluid deficits. Long-term steroid therapy with corticosteroids may help alleviate the symptoms over time. If the disease is localized, radiation therapy may be an option as determined by your vet. Ongoing treatment is also aimed at supportive care including control of seizures and nutritional support.

The prognosis for GME is highly variable and will depend on the form of the disease and where its located. While there is no known way to prevent GME, your vet will likely schedule follow-up exams once or twice per month for neurological testing and to make sure the dog is getting adequate nutrition.