North American Veterinary Licensing Examination (NAVLE) Practice Test 2025 - Free NAVLE Practice Questions and Study Guide

Neomycin is an aminoglycoside antibiotic that is well-known for its potential to cause nephrotoxicity, especially when used in high doses or for extended periods. In horses, the administration of neomycin can lead to acute renal failure due to its accumulation in the renal tubular cells, which can result in cellular damage and dysfunction. This drug's side effect profile includes a risk of causing significant renal impairment, and monitoring kidney function during its use is essential.

In contrast, oxytetracycline, while it has a risk of causing renal issues, is generally less nephrotoxic than neomycin, particularly when used at standard doses. Xylazine, a sedative and analgesic, primarily affects the central nervous system and may lead to transient hypotension but is not directly associated with acute renal failure. Dexamethasone, a corticosteroid, can influence renal function but does not typically cause acute renal failure like aminoglycosides do.

Overall, the association of neomycin with acute kidney injury in horses makes it the most likely candidate in this context.