Veterinary use of Enrofloxacin

Enrofloxacin is a broad-spectrum, concentration-dependent*, bactericidal antibiotic used in a wide variety of species. A fluroquinolone, it is believed to act by inhibiting bacteria DNA-gyrase preventing DNA supercoiling and synthesis. Enrofloxacin has demonstrated a significant post-antibiotic effect (PAE)** for both gram – and + bacteria including Pseudomonas aeruginosa, Klebsiella spp., E coli, Enterobacter, Campylobacter, Shigella, , Salmonella, Haemophilus, Proteus, Yersinia, Serratia, Vibrio, Brucella, Chlamydia, Staphylococci, Mycoplasma, and Mycobacterium, with a spectrum of activity similar to ciprofloxacin. It is not effective against anaerobic bacteria and has variable activity against the majority of Streptococus infections. Enrofloxacin’s bioavailability allows it to be rapidly and well-absorbed following ingestion with concentrations reaching therapeutic levels in most tissues of the body, with the exception of spinal fluid. Enrofloxacin is eliminated by both renal and hepatic metabolism, therefore animals with severe kidney or liver problems may need a reduced dose. It is contraindicated in dogs in the rapid growth phase, and any animal with seizure disorder.

Dosing: Dogs – 5-20mg/kg PO QD

Cats – 5mg/kg PO QD or split BID (lower dosage needed due to risk of ocular toxicity)

Ferrets – 10-20mg/kg PO BID

Rodents (Rabbits, Gerbils, Guinea Pigs, etc.) – 5-10mg/kg PO BID or 5-20mg/kg PO QD

Birds – 1.5-2.5mg/kg PO BID

*Concentration-dependent antibiotics pharmacodynamic/pharmacokinetic profile favors increasing concentrations from levels slightly above the MIC to levels far above the MIC to increase the rate of bactericidal activity and decrease the bacterial load. (Higher doses may achieve better/faster outcomes).

**PAE is also concentration-dependent. If PAEs are long, drug levels can be below the MIC for extended periods without loss of efficacy, allowing less frequent dosing.

1. Plumb DC. Enrofloxacin. Veterinary Drug Handbook, fifth edition.
2. Wetzstein HG, DeJong A: In vitro bactericidal activity and post antibiotic effect of fluoroquinolones used in veterinary medicine. Suppl Compend Contin Educ Pract Vet 18 (2): 22-29, 1996.
3. Scheer M: Concentrations of active ingredient in the serum and in tissues after oral and parenteral administration of Baytril. Vet Med Rev 2: 104-118, 1987.