ABSTRACT

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorder in which antibodies are produced against nicotinic acetylcholine (ACh) receptors of skeletal muscle. The resulting impairment of neuromuscular transmission is clinically manifested as muscle weakness. Abundant information exists concerning the pathophysiology, epidemiology, and diagnosis of MG. However, few clinical data address therapeutic efficacy and overall disease prognosis in dogs. The underlying abnormality in MG is a lack of functional ACh receptors at the end-plate regions of skeletal muscle. Dog breeds commonly associated with MG include golden retrievers, Labrador retrievers, and German shepherds. Common historical complaints offered by owners of myasthenic dogs and cats include swallowing difficulty, vomiting/regurgitation, hypersalivation, coughing, labored breathing, and limb muscle weakness. Anticholinesterase therapy comprises the cornerstone of MG treatment in dogs and cats. Anticholinesterase therapy is most effective in improving ambulatory function in generalized myasthenics. Anticholinesterase drugs have less efficacy in improving esophageal function compared to limb function.