Myasthenia Gravis In Dogs: Symptoms, Causes, And Treatments

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Myasthenia gravis in dogs is a disorder that breaks down transmission of signals between the nerves and the muscles. This results in muscle weakness and fatigue in canines who suffer from it. Myasthenia gravis can be congenital and detectable in puppies at six to eight weeks of age, or it can be acquired and appear at one to four years of age or nine to thirteen years of age, and rarely any age in between. Often it affects the muscles in the esophagus, though it can affect muscles elsewhere in the body. If you notice the signs of myasthenia gravis in your dog, you should see a veterinarian immediately. Here is what you should know about the symptoms, causes, and treatments for myasthenia gravis in dogs.

Symptoms Of Myasthenia Gravis In Dogs

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A common symptom of myasthenia gravis in dogs is weakness in the esophagus that leads to dilation, which can hold food instead of allowing it to pass into the stomach. This is called megaesophagus. Often, it will lead to symptoms such as the following.

  • Regurgitation
  • Trouble swallowing food or drinking
  • Retching
  • Abdominal contractions similar to those associated with vomiting

The symptoms of myasthenia gravis are not always limited to the esophagus or throat. There are a host of other signs of the disorder that you should look out for and consult a veterinarian if you spot them. Here are several other symptoms you might expect to see in a dog with myasthenia gravis.

  • Voice changes
  • Weakness or cramping that gets worse with exercise and better with rest
  • Inability to close the eyes or blink
  • Sleeping with eyes open
  • Absent gag reflex
  • Excessive drooling
  • Difficulty breathing or aspiration pneumonia
  • Tumor in the chest cavity called a thymoma

Causes Of Myasthenia Gravis In Dogs

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Myasthenia gravis is often a congenital disease, meaning it is present from birth in dogs. Even when it is acquired after puppyhood, a combination of genetic factors usually interact with environmental factors to cause the disease. Myasthenia gravis is immune-mediated, meaning the immune system response is abnormal and causes the symptoms of the disease. Like many autoimmune diseases, myasthenia gravis has a genetic component, and certain breeds are more at risk. Breeds that are predisposed include Akitas, Golden Retrievers, Great Danes, Labrador Retrievers, Newfoundlands, and Scottish Terriers. Non-spayed female dogs are also at greater risk. Myasthenia gravis may appear as a secondary condition to certain forms of cancer, as well.

Treatments For Myasthenia Gravis In Dogs

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Some dogs that develop myasthenia gravis will end up inhaling the food, liquid, or vomit that is regurgitated and develop aspiration pneumonia. These dogs may require oxygen therapy, antibiotics, and intravenous fluids. If a dog is unable to eat with regurgitating, a feeding tube may be required until the dog is stabilized. In cases where a thymoma, or chest tumor, is found, surgery will likely be required.

Anticholinesterase drugs may be used to suppress antibodies in the immune system that are attacking the muscle receptors, which can improve muscle strength and allow the muscles to function properly. Anti-acetylcholinesterase medications may then be prescribed for the rest of the dog’s life.

After recovery, food and water bowls should be elevated and a dog’s head should stay elevated for ten to fifteen minutes after eating. This will reduce the regurgitation and risk of aspiration pneumonia. Your vet may prescribe steroids or other immune system suppressants for ongoing treatment.

Has your dog ever suffered from myasthenia gravis? What treatment did your veterinarian recommend? Let us know in the comments below!