Postanesthetic Death in a Cat With Myopathy

Abstract

There are few reports of naturally occurring muscular dystrophy in domestic animals. Herein, we describe a case of muscular dystrophy in a 4-year-old neutered male American domestic shorthair cat that died unexpectedly following anesthesia for an elective surgical procedure. Macroscopic muscular hypertrophy and histologic evidence of myofiber size variation, mineralization, myofiber degeneration, and necrosis were compatible with a diagnosis of muscular dystrophy. Extensive endomysial fibrosis was noted histologically in the diaphragm. A complete absence of dystrophin protein in Western blot confirmed the diagnosis of Duchenne muscular dystrophy. Immunofluorescence microscopy revealed reduced levels of dystrophin-associated proteins and an upregulation of utrophin at the sarcolemma. Anesthetic deaths can occur in dystrophin-deficient cats, and therefore muscular dystrophy and the associated cardiomyopathy should be considered in the differential diagnoses for perianesthetic death in cats.

Dystrophin (DMD) Missense Variant in Cats with Becker-Type Muscular Dystrophy

“…Positive acid phosphatase activity highlighted necrotizing myofibers. Together, these histopathological features were consistent with a dystrophic myopathy as previously described in domestic cats with X-linked muscular dystrophy [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 41 ]…”

“…It is well recognized that dystrophin deficiency and dysfunction are associated with impaired stability of the entire dystrophin-associated protein complex, and thus reduced amounts of any of its muscle proteins may be expected [ 53 ]. Furthermore, previously studied dystrophin-deficient cats also exhibited reduced complex proteins [ 12 ]. All previously reported cats were classified as having Duchenne-type muscular dystrophy, including the recently described dystrophic Maine Coon cat [ 51 ].…”

“…Dystrophin-deficient dogs exhibit very similar clinical features, and thus became the favorite animal model to investigate this disorder and assess novel therapies at the preclinical stage (Online Mendelian Inheritance in Animals [OMIA] #001081-9615) [ 5 , 6 , 7 ]. In contrast to dystrophin-deficient humans and dogs, cats with X-linked muscular dystrophy exhibit predominantly muscular hypertrophy rather than dystrophy (OMIA #001081-9685) [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. More recently, several juvenile pigs with dystrophin deficiency or insufficiency have been described (OMIA #001081-9823 [Duchenne]; #001888-9823 [Becker]) and few became useful disease models [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”

Dystrophin (DMD) missense variant in cats with Becker type muscular dystrophy

“…Positive acid phosphatase activity highlighted necrotizing myofibers. Together, these histopathological features were consistent with a dystrophic myopathy as previously described in domestic cats with X-linked muscular dystrophy [8][9][10][11][12][13][14]41] Immunohistochemistry of muscle from cat #1 revealed irregular and partially deficient expression of both DYS1 (rod domain) and DYS2 (carboxy terminus) (Figure 2d,e,d-2,e-2). Moreover, antibody reactivity of βand γ-sarcoglycans (Figure 2g,h) as well as β-dystroglycan was diminished and uneven compared to the feline controls.…”

A feline orthologue of the human MYH7 c.5647G>A (p.(Glu1883Lys)) variant causes hypertrophic cardiomyopathy in a Domestic Shorthair cat

“…However, it is also possible that some degree of muscle weakness was present, but not recognized, as even severe myopathy in cats can go unnoticed by the owner and veterinarian. 40,41 Histopathology of skeletal muscles was not available to compare to the MSM phenotype in humans.…”