North American Veterinary Licensing Examination (NAVLE) Practice Test

The presence of pseudo-diphtheritic membranes in the intestines of a calf with diarrhea is indicative of salmonellosis. This condition is characterized by severe inflammation and necrosis of the intestinal mucosa caused by Salmonella bacteria. The membranes that are observed resemble diphtheritic lesions, which are formed due to the necrotizing effect of the infection on the intestinal lining. Salmonellosis typically leads to a more severe form of diarrhea in calves, and the necrotizing enteritis can result in the development of these pseudo-membranes. Recognizing this clinical sign is crucial for diagnosis and treatment, as prompt veterinary intervention is necessary to manage the disease and prevent further complications. While other conditions listed can cause diarrhea in calves, such as coccidiosis, bovine viral diarrhea (mucosal form), and cryptosporidiosis, they do not typically present with pseudo-diphtheritic membranes. Instead, these conditions have different pathological features and clinical signs that help differentiate them from salmonellosis. For instance, coccidiosis may show bloody diarrhea but lacks the characteristic necrotic membranes; bovine viral diarrhea may cause similar symptoms but is associated more with ulceration and less with the membranous appearance;