Clostridium chauvoei causes blackleg in cattle. The disease has been reported worldwide, and although it can be prevented by vaccination, sporadic cases and occasional outbreaks still occur. We describe a case of blackleg in a 2-y-old, pregnant Gyr cow with in utero transmission to the fetus. The cow had characteristic gross and microscopic lesions of blackleg including widespread necrohemorrhagic and emphysematous skeletal and myocardial myositis, and fibrinous pericarditis. Her uterus contained a near-term, markedly emphysematous fetus with skeletal muscle and myocardial lesions similar to those seen in the dam. Histopathology of dam and fetal tissues revealed numerous gram-positive bacilli, many of them with sub-terminal spores, in multiple tissues. These bacilli were identified as C. chauvoei by immunohistochemistry. Anaerobic culture and fluorescent antibody tests performed on skeletal muscle from both the dam and fetus were positive for C. chauvoei, confirming a diagnosis of blackleg. Blackleg is a so-called endogenous infection, and the currently accepted pathogenesis involves ingestion of spores that are transported to muscle tissues where they lie dormant until anaerobiosis prompts germination. Germinating bacteria are histotoxic, producing severe, local necrosis and ultimately lethal toxemia. This model, however, has not been confirmed experimentally and also fails to explain some cases of the disease. A presumptive diagnosis of blackleg is based on clinical, gross, and histologic findings. Diagnostic confirmation necessitates the detection of C. chauvoei by culture, PCR, or immunodetection methods.

BackgroundKnowledge of the mineral composition of the causative urolith is important to develop preventative strategies. Advances in analytic techniques have led to detection of urolith components not previously recognized.Hypothesis/ObjectivesThe objectives of this study were to characterize uroliths in sheep and goats structurally and clinically. We hypothesized that amorphous magnesium calcium phosphate (AMCP) would be a naturally occurring urolith type in sheep and goats.AnimalsForty‐nine sheep and goats presenting for obstructive urolithiasis from June 15, 2014 through June 14, 2016 were reviewed along with the demographic data of all small ruminants admitted during that same period.MethodsMedical records were reviewed for demographic and historical data, and 36 uroliths obtained from these cases during diagnostic or therapeutic procedures were analyzed by infrared spectroscopy to determine chemical composition.ResultsAMCP is a naturally occurring urolith type in obstructed male sheep and goats and was the most common urolith type in this study, where it occurred as a majority component with struvite (39% of uroliths) or as a pure component (11%). Pure struvite was found in 1 urolith (2%). Calcium carbonate was the second most frequent urolith with 31% of uroliths being pure calcium carbonate.Conclusions and Clinical ImportanceThis study demonstrates that uroliths, which appear consistent with struvite, could actually be calcium‐containing AMCP. Urolith analysis is critical in determining mineral content of uroliths to guide dietary recommendations for prevention.

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