Can leptospirosis be a differential diagnosis for fever of unknown origin in dogs?

• A. Yes
• B. No
• C. Only with kidney disease
• D. Only if vaccinated

Answer: (A)

Fever of unknown origin can be caused by a wide range of infectious diseases, and leptospirosis fits right into that differential because it often presents with nonspecific systemic signs rather than a single clear focus. Infected dogs may be febrile with malaise, vomiting, or reduced appetite, and renal problems or liver involvement can develop variably or be subtle at the outset. Exposure to contaminated water, soil, or urine from wildlife or rodents is a common risk, making leptospirosis a realistic consideration in FUO workups.

Vaccination reduces risk but does not guarantee protection against all serovars, and infection can occur in both vaccinated and unvaccinated dogs. Importantly, the lack of kidney disease at presentation does not exclude leptospirosis, nor does the presence of vaccination status confirm it. Because of the potential for organ damage and zoonotic transmission, leptospirosis should be included in the differential when evaluating fever of unknown origin in dogs.

In short, yes — leptospirosis can be a differential diagnosis for fever of unknown origin in dogs.