Myasthenia Gravis

Myasthenia Gravis is not common but has been seen in Irish Wolfhounds. This is a disease of the nervous system that can be present at birth (congenital), but is usually acquired in adult dogs. The most common cause is an autoimmune condition in which antibodies in the blood attack receptors for a chemical called acetylcholine, that transmit nerve impulses to the muscles.

Dogs who are affected with myasthenia gravis typically show stiffness, shaking, and weakness after exercise, which often go away after rest. The muscles in the head and throat may also be affected, leading to a drooping appearance and difficulty swallowing, due to acquired megaesophagus. As result, dogs may aspirate food into the windpipe, causing pneumonia.

If symptoms resolve after giving a shot of a chemical similar to acetylcholine, your veterinarian will suggest the dog is positive for myasthenia gravis. Checking for specific antibodies in the blood will provide a definite diagnosis of the acquired disease. A muscle biopsy is performed for diagnosis of congenital cases.

Daily administration of drugs to replace the missing acetylcholine is the preferred treatment. High doses of corticosteroids to suppress the autoimmune response may also be prescribed by your veterinarian. Prognosis is generally good, and many cases clear up on their own.

See the megaesophagus and pneumonia sections for treatment of these symptoms of myasthenia gravis.

For more information, visit the UC Davis Myasthenia Gravis page.

This page was last updated 01/04/2021.