Pathology of blackleg in cattle in California, 1991–2015

Abstract

Blackleg is an infectious disease of cattle and rarely other ruminants, produced by Clostridium chauvoei and characterized by necrotizing myositis. In most cases of blackleg, the large muscles of the pectoral and pelvic girdles are affected, with other skeletal muscles and the heart involved less frequently. We studied 29 blackleg cases selected from the archives of the California Animal Health and Food Safety Laboratory, 1991-2015. Immunohistochemistry was also evaluated to detect C. chauvoei in formalin-fixed, paraffin-embedded (FFPE) tissues of cattle. Nineteen animals had gross and/or microscopic lesions in both skeletal muscle and heart, 9 had lesions in the skeletal musculature alone, and 1 in the heart alone. Gross lesions in the skeletal musculature involved the following muscle groups: hindquarters (n = 8), forequarters (n = 5), neck (n = 5), lumbar area (n = 3), brisket (n = 2), diaphragm (n = 2), abdominal wall (n = 1), thoracic wall (n = 1), and tongue (n = 1). Of the 20 animals that had lesions in the heart, 11 had pericarditis and myocarditis; 7 had pericarditis, myocarditis, and endocarditis; and 1 each had pericarditis and myocarditis. Immunohistochemistry was 100% sensitive to detect C. chauvoei in FFPE skeletal muscle and/or heart of cattle with blackleg. Simultaneous lesions in skeletal musculature and heart were relatively common in blackleg cases in California; the most affected skeletal muscles were those of the hindlimbs.

Prevalence of cardiac lesions in cases of bovine clostridial myositis

“…Thirty-seven cases of blackleg were identi ed. The presence of Clostridium chauvoei in the lesions was con rmed by immunohistochemistry [1] in 25 cases (67.6%), by culture and immuno uorescence in 11 cases (29.7%), and by polymerase chain reaction in 1 case (2.7%). In 32 cases (86.5%), affected skeletal muscle (n=6), heart (n=6), or both (n=20) were examined microscopically, and, when present, the lesions were consistent with blackleg in all of these cases.…”

“…Clostridial myositis, or blackleg, is caused by the bacterium Clostridium chauvoei. [1][2][3][4][5] Affected cattle are typically pastured and are between 6 and 24 months of age. [3] Ingested spores of C. chauvoei from contaminated soil are transported across the intestinal mucosa, presumably via M cells, and then disseminated to tissues, including striated muscle, where they are phagocytized by resident macrophages and survive intracellularly without deleterious effects.…”

“…[ 1− 6] Similarly, the microscopic changes are primarily necrosis and hemorrhage with edema, emphysema, and varying degrees of in ammation. [1,2,5] Associated lesions include brinohemorrhagic pleuritis, pericarditis, and mural or valvular endocarditis. If present, valvular endocarditis typically affects the right atrioventricular valve.…”

“…[1 − 3 ,5,7-10] The prevalence of cardiac lesions in cattle with blackleg in California was recently reported to be 69%. [1] This study aimed to determine the prevalence of cardiac lesions in cases of blackleg in Tennessee.…”

Pathological and clinical investigations of an outbreak of Blackleg disease due to C. chauvoei in cattle in Punjab, Pakistan

“…The blackleg disease is causing huge economic losses and is a limiting factor in commercial dairy animals. Previous studies on blackleg infection usually revolved around molecular identification [18,19], and classical skeletal muscle pathology [20]. For diagnosis of blackleg infection, clinical ailments and necropsy lesions may be sufficient, however, histopathological and blood biochemical investigations in this study are useful for the understanding of pathogenesis, therapeutic procedures and control strategies of visceral blackleg in dairy animals.…”