Which may be effective in treating chronic diarrhea in dogs but signs will often recur after stopping medication?

• A. Metronidazole
• B. Tylosin
• C. Prednisone
• D. Loperamide

Answer: (B)

Chronic diarrhea in dogs can be driven by an antibiotic-responsive enteropathy, where altering the gut bacteria with a specific antibiotic improves the signs, but the problem often re-emerges once the drug is stopped. Tylosin fits this scenario well: it’s a macrolide antibiotic given at a low daily dose that modulates the intestinal microbial population and reduces overgrowth associated with chronic diarrhea. Many dogs show clinical improvement on tylosin, but because the underlying dysbiosis isn’t permanently resolved, signs frequently recur when the medication is discontinued, making it a therapy that controls the problem rather than cures it.

Other options can be helpful in different contexts (metronidazole for certain inflammatory or overgrowth patterns with potential systemic side effects; prednisone for immune-mediated intestinal disease with relapse upon taper; loperamide providing only symptomatic relief). However, the hallmark here is the pattern of improvement with targeted antibiotic therapy and relapse after stopping, which is characteristic of tylosin use in antibiotic-responsive enteropathy.