Is Enrofloxacin safe for dogs and cats?

Enrofloxacin (Baytril) is FDA-approved for use in dogs for skin and soft tissue infections, respiratory tract infections, urinary tract infections, and other susceptible bacterial infections. The primary safety concern in dogs is cartilage toxicity (arthropathy) in rapidly growing animals — fluoroquinolones inhibit topoisomerase II in chondrocytes, causing cartilage erosion and joint swelling. FDA restricts enrofloxacin use in dogs under 12 months of age (or under 18 months for large/giant breeds expected to exceed 45 kg). Retinal toxicity in dogs has been reported experimentally at very high doses but is not a clinical concern at approved doses. In adult dogs at therapeutic doses, enrofloxacin is generally well-tolerated; GI effects (vomiting, anorexia) are the most common adverse reactions. Antimicrobial resistance transmission — particularly fluoroquinolone-resistant Campylobacter in pets acquiring infections from or transmitting to human household contacts — is a public health concern of growing regulatory attention.

Enrofloxacin is a veterinary fluoroquinolone antibiotic (Baytril) associated with a well-documented, dose-dependent risk of irreversible retinal degeneration and blindness in cats. The mechanism involves accumulation of enrofloxacin and its primary metabolite ciprofloxacin in feline retinal pigment epithelium (RPE), followed by photoreceptor (rod and cone) apoptosis. Retinal toxicity has been reported at doses at or above 5 mg/kg/day; FDA reviewed post-market safety data and in 2004 amended the label to restrict feline dosing to 2.27 mg/kg (approximately 5 mg/cat) once daily and to contraindicate use in cats with pre-existing ocular disease. Even at the labeled dose, some cats exhibit subclinical electroretinographic changes. Clinical presentations range from acute mydriasis and visual impairment to complete irreversible blindness. Cats with hypertension, CKD, or who are receiving other medications affecting ocular blood flow may be at higher risk. Ciprofloxacin (the human oral fluoroquinolone that is enrofloxacin's major metabolite) also carries retinal toxicity risk in cats at equivalent doses. Ophthalmologic monitoring during enrofloxacin therapy in cats is recommended.