Always examine the joints

Humeral head, juvenile dog, experimental oral administration of fluoroquinolone antibiotic. Chondropathy secondary to administration of quinolone class of antibiotics (olfloxacin, ciprofloxacin, levofloxacin, etc.) has been known for around 40 years. Read the Papich Handbook of Veterinary Drugs, and you'll find a warning not to administer quinolone antibiotics to growing dogs. While dogs reportedly have more severe reactions, experimental and clinical cases in other species are also described. Quinolones are not given to humans less than 18 years of age, for example. The microscopic lesion of vesiculation and cavitation secondary to necrosis of the middle layer of the articular cartilage is unusual and characteristic. The mechanism of action, whether on-target or off-target, is mysterious. Researchers have proposed inhibition of proteoglycan synthesis or promotion of matrix metalloproteinases. Photo courtesy of Steven Weisbrode and The OSU CVM. Read more: Kabe et al. Veterinary Pathology. 2004. PMID: 15557076