Ca. Jackson et al., BLACKLEG - A NEW PERSPECTIVE ON AN OLD DISEASE, The Compendium on continuing education for the practicing veterinarian, 17(10), 1995, pp. 1299
Two first-calf Holstein heifers with a history of anorexia, depression
, decreased milk production, severe hindlimb lameness, and swelling of
18 to 24 hours in duration were examined in February of 1993. The two
animals were from a herd that, within a three-week period, had four b
red heifers and one first-calf heifer die suddenly after exhibiting si
milar clinical signs. A pure culture of Clostridium chauvoei was isola
ted from the affected legs of both examined heifers. Fluorescent antib
ody examination was also positive for C. chauvoei. One heifer became r
ecumbent and was euthanatized. The second heifer was treated and survi
ved. None of the affected cattle in this outbreak was febrile. Despite
an overwhelming infection, the two heifers had either normal or sligh
tly elevated white blood cell counts and normal aspartate transaminase
and creatine kinase serum chemistry values. Therefore, blood work may
not be helpful in the diagnosis of clostridial myositis. Gram-stained
smears or fluorescent antibody testing of the affected muscle can pro
vide a rapid diagnosis of clostridial myositis. Bacterial culture can
identify the species and confirm the diagnosis.