Myasthenia Gravis
Recently, I saw a patient that was diagnosed with myasthenia gravis (MG). She's a middle-aged German Shorthaired Pointer (GSP) who was carried into the hospital by her owner because she was too weak to navigate the stairs on her own. It is always alarming when a GSP is unable to do anything short of leaping up a full flight of stairs in one bound. After her exam and her partial recovery while we spoke, I had my suspicions! Myasthenia gravis is a neuromuscular disease that causes muscle weakness. Some animals are born affected; others develop it secondary to specific types of tumors or for unknown reasons. There are certain breeds that are more commonly affected and GSPs are one of them. Myasthenia gravis can cause mild symptoms, like my patient, who become weak after activity and then recovered with rest. My patient was up and pacing normally by the end of our exam. But a quick jaunt around the lobby made her wobble in the rear legs again. Weakness can also be so severe the dog isn’t able to raise their head, let alone stand.
The muscle weakness can also involve the muscles of the throat and esophagus which causes difficulty breathing, swallowing, excessive drooling, and regurgitation of food (which can lead to aspiration pneumonia). Some owners notice their bark changes. To diagnose the disease, there is a special test that is used to identify the presence of disease-causing antibodies. There is also an injection that helps diagnose MG. If the pet has MG, once the injection is given they are able to rise and walk normally for a minute or two. Obviously not useful as a treatment, but it can be dramatic to see! A suspected diagnosis of MG leads to a variety of other tests to look for the underlying cause and complications associated with the disease. Long-term prognosis depends on the results of these tests and response to treatment. My patient is expected to continue to lead a normal, exuberant life though she may have to take that flight of stairs one step at a time from now on.
--Dr. Olson
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Dr. Olson practices small animal medicine in Denver, CO and is a regular contributor to Wag Reflex.
Karen on June 04, 2009 at 03:03 PM
How interesting. I too have the disease and never imagined that I would share this with the rest of the animal kingdom. It was years in searching before mine was diagnosed so I can only imagine how many pets go untreated and miserable and limited! Thanks for the insight.
joesen on December 14, 2010 at 09:41 PM
A suspected diagnosis of MG leads to a variety of other tests to look for the underlying cause and complications associated with the disease. Long-term prognosis depends on the results of these tests and response to treatment. My patient is expected to continue to lead a normal, exuberant life though she may have to take that flight of stairs one step at a time from now on.