Acquired Myathenia Gravis

Acquired MG is an autoimmune disease in which the body’s immune system mistakenly attacks and destroys special proteins (acetylcholine receptors) located on the muscle surface where the nerve attaches to the muscle.

Muscle weakness is the distinctive feature of MG. The muscles affected are voluntary or striated muscles and different muscle groups can affect different dogs, making clinical signs different as well and diagnosis of MG can be difficult. A common sign is regurgitation. Excessive salivation as well as multiple attempts at swallowing food may be another signal. A high-pitch bark or no bark may also be another sign as well as the dog appearing to sleep with his eyes open as the eyelid muscles may be too weak.

A very severe form of MG has also been described in which there is a rapid onset of muscle weakness involving esophagus and respiratory muscles. Treatment requires intensive care including ventilatory support.

There are two forms of MG found in dogs: congenital (when the animal is born with the disease) and acquired (where the disease develops over the course of the animal’s life). The acquired form is the most common type found in dogs and it is seen in certain breeds more commonly, including the Akita, the German Shorthaired Point, the German Shepherd, the Golden Retriever and some terrier breeds. A rare congenital form of the disease has also been seen in Jack Russells, Springer Spaniels and Smooth Haired Fox Terriers.

Additional information:

• Myasthenia Gravis – Davies Veterinary Specialists

Note: This section of the Canada’s Guide to Dogs website is intended as a source of information only. It is not intended as a substitute for professional care. Always consult with your Veterinarian about health related matters.