Infectious Colitis in Dogs and Cats: Diagnosis, Management, and Clinical Outcomes

Infectious colitis can cause large intestinal diarrhea and, in severe cases, systemic illness in dogs and cats. Causative agents include bacteria, protozoa, helminths, trematodes, fungi, oomycetes, and algae, with prevalence influenced by signalment, immune status, and environmental exposure. Parasites such as Trichuris vulpis and Tritrichomonas blagburni are common and should be routinely screened for. Management of bacterial colitis should prioritize supportive care and addressing underlying causes rather than routine antimicrobials. Disseminated fungal, oomycete, and algal infections often require prolonged, multiagent therapy. Escherichia coli-associated granulomatous colitis necessitates histopathologic diagnosis and susceptibility-guided antimicrobials. Prognosis varies with infectious agent and presence of dissemination.