An overview of calf diarrhea - infectious etiology, diagnosis, and intervention

Cho, Yong-il; Yoon, Kyoung-Jin

Proper specimen collection and delivery to a diagnostic lab is commonly neglected, and significantly impacts the diagnostic outcome. Antemortem samples for diagnostic testing should minimally include feces from acutely diarrheic animals prior to therapy with optional blood samples. Necropsy specimens from freshly sacrificed, moribund, or euthanized calves are of great value for diagnosis during severe outbreaks. Fresh and formalin-fixed gastrointestinal tissues (abomasum, small intestine, or colon) including ones from regional lymph nodes and liver should be collected along with colonic contents. Fresh fecal samples should be directly recovered from diarrheic animal into a specimen container with either rectal swabs or by rectal stimulation while avoiding environmental contamination (by soil, urine, or other feces). Once collected, the sample should be stored in a transporting medium or special stool container with refrigeration to maintain pathogen viability and sample integrity (i.e., reduced overgrowth of undesired bacteria and prevention of nucleic acid degradation) [75] . Samples of anaerobic bacteria (e.g., C. perfringens) should be kept in an oxygen-free transport medium during shipping if possible.