小动物重症肌无力
Myasthenia gravis is an immune-mediated paraneoplastic syndrome, resulting from antibody production against nicotinic acetylcholine (ACh) receptors within the neuromuscular junction, that occurs most commonly in dogs and cats with thymoma (see ) (1).
Radiograph of a dog, showing a cranial mediastinal mass (arrows) consistent with thymoma and concurrent myasthenia gravis.
Courtesy of Dr. Brooke Britton.
Other tumors reported to cause this syndrome include osteosarcoma, oral sarcomas, cholangiocellular carcinoma, and nonepitheliotropic lymphoma. Generalized myasthenia gravis is usually associated with exercise-induced muscular weakness, with concurrent weakness of the muscles of the esophagus, face, and pharynx/larynx.
Definitive diagnosis of myasthenia gravis is based on testing for circulating antibodies against the ACh receptor. A positive neostigmine test also supports the diagnosis.
Surgical removal of thymoma or the underlying tumor is recommended; however, postoperative improvement is inconsistent. Anticholinesterase therapy with pyridostigmine bromide and immunosuppressive therapy are recommended before surgery, when possible, to decrease the risk of perioperative aspiration pneumonia (1).
Morbidity and mortality rates are substantial in patients with megaesophagus secondary to myasthenia gravis, even if the underlying tumor is removed.
了解更多信息
Bailey DB. Paraneoplastic syndromes. In: Vail DM, Thamm DH, Lipták JM, eds. Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed. Elsevier; 2020:98-100.
Braund KG. Remote effects of cancer on the nervous system. Semin Vet Med Surg Small Anim. 1990;5(4):262-270.
Saylor SE, Oblak ML, Risselada M, Thieman KM, McKenna C, Scharf VF. Preoperative management and postoperative complications in 9 dogs undergoing surgical treatment of thymic-associated myasthenia gravis. Can Vet J. 2024;65(7):682-691.
Also see pet owner content regarding peripheral nerve disorders in dogs and cats.
参考文献
Robat CS, Cesario L, Gaeta R, et al. Clinical features, treatment options, and outcome in dogs with thymoma: 116 cases (1999–2010). J Vet Med Assoc. 2013;243(10):1448-1454. doi:10.2460/javma.243.10.1448
