{"id":34841,"date":"2024-10-18T20:18:42","date_gmt":"2024-10-18T20:18:42","guid":{"rendered":"https:\/\/todaysveterinarypractice.com\/?p=34841"},"modified":"2025-12-18T21:24:26","modified_gmt":"2025-12-18T21:24:26","slug":"acquired-myasthenia-gravis-in-companion-animals","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarypractice.com\/neurology\/acquired-myasthenia-gravis-in-companion-animals\/","title":{"rendered":"Acquired Myasthenia Gravis in Companion Animals"},"content":{"rendered":"

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Abstract<\/strong><\/p>\n

Acquired myasthenia gravis is a common neuromuscular disease that affects dogs more than cats. It is an immune-mediated condition affecting the neuromuscular junction; treatment requires use of anticholinesterase medications and possibly other medications including immunosuppressants (e.g., prednisone, mycophenolate, cyclosporine). Treatment can also include supportive care, including elevated feedings, modifications to food and water administration, and constant monitoring for development of aspiration pneumonia. There are also alternative therapies for myasthenia gravis that should be further evaluated. The long-term prognosis is guarded, and long-term management can be frustrating.<\/p>\n

Take-Home Points<\/strong><\/p>\n

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  • Acquired myasthenia gravis has 3 forms: focal, generalized, and fulminant.<\/li>\n
  • The most common treatment involves anticholinesterase medications (e.g., pyridostigmine), although steroids and other immunosuppressive medications are also frequently used.<\/li>\n
  • Patients with myasthenia gravis are at significant risk for aspiration pneumonia, sometimes for life if megaesophagus does not resolve.<\/li>\n
  • Some newer (to veterinary medicine) modalities can be used to attempt to reduce autoantibody burden; they are more commonly accessible in academic settings.<\/li>\n
  • The prognosis for acquired myasthenia gravis is guarded.<\/li>\n<\/ul>\n

    <\/div><\/div><\/p>\n

    Acquired myasthenia gravis is among the more common neuromuscular diseases of dogs; it can also affect cats, although rarely, and typically affects purebred cats (e.g., Abyssinian, Somali). Acquired myasthenia gravis is an immune-mediated disease of the neuromuscular junction characterized by the presence of autoantibodies to the nicotinic acetylcholine receptor, located on the postsynaptic membrane of the neuromuscular junction. Thus, fewer receptors are available for acetylcholine to attach to, resulting in weakness of striated muscle.1<\/sup> Affected muscles are in the appendicular and axial musculoskeletal systems, along with the oropharynx and most of the esophagus in dogs. Megaesophagus rarely occurs in cats with myasthenia gravis because their esophagus lacks striated muscle. <\/span><\/p>\n

    Myasthenia gravis can be primarily immune-mediated, or it can be secondary to a cranial mediastinal mass, most commonly a thymoma, although other types of tumors have also been associated. Among cats with myasthenia gravis, the condition is secondary to a cranial mediastinal mass in approximately 50%.2,3<\/sup> Although congenital myasthenia gravis is a concern for dogs and cats, it is rare and is not covered in this article.<\/span><\/p>\n

    The 3 main forms of acquired myasthenia gravis are focal, generalized, and fulminant. The focal form is largely localized to the oroesophageal muscles; the generalized form includes appendicular muscle weakness along with megaesophagus; and the fulminant form is an acute, severe generalized form that can result in the need for ventilatory support.3,4<\/sup><\/span><\/p>\n