Enrofloxacin
1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid
Also known as: Baytril · Enrocare · Enrox · Xeden · Zobuxa · Bay-Vp-2674 · Enrofloxacine · Enrofloxacino · Enrofloxacinum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5-20 mg/kg per day PO | PO | q24h or divided q12h | At least 2-3 days beyond cessation of clinical signs, max 30 days | 🌎 NA |
| Sepsis | 5-20 mg/kg IV | IV | q12h | — | 🌎 NA |
| Skin, urinary infections | 2.5-5 mg/kg PO | PO | q12h | 7-14 days | 🌎 NA |
| Deep pyodermas, complicated urinary infections | 5 mg/kg PO | PO | q24h | 7-14 days (up to 10-12 weeks for deep pyoderma) | 🌎 NA |
| Lower respiratory tract infections | 5-10 mg/kg PO | PO | q24h | 7-84 days | 🌎 NA |
| Prostate infections | 5 mg/kg PO | PO | q12h | 7-14 days | 🌎 NA |
| Histiocytic ulcerative colitis | 5 mg/kg PO | PO | q12h | 21-90 days | 🌎 NA |
| Histiocytic ulcerative colitis | 5-10 mg/kg PO | PO | q24h | At least 4-6 weeks | 🌎 NA |
| Hemotropic mycoplasmosis | 5 mg/kg PO, IM | PO, IM | q12h | 7-14 days | 🌎 NA |
| Systemic orthopedic infections | 5-11 mg/kg PO, IV, IM, SC | PO, IV, IM, SC | q12h | 10 days | 🌎 NA |
| Pseudomonas infections in soft tissues | 11-20 mg/kg PO, IM, SC | PO, IM, SC | q12h | 7 days minimum | 🌎 NA |
| Bacteremia, sepsis | 11 mg/kg PO, IV, IM, SC | PO, IV, IM, SC | q12h | As long as necessary | 🌎 NA |
| Susceptible infections | 5 mg/kg | SC | q24h | Not specified | 🌍 EU |
| Prostatitis or specific sites | 10 mg/kg | SC | q24h | Not specified | 🌍 EU |
- Susceptible infections: Pulse dosing regimens may be effective.
- Prostatitis or specific sites: Even higher doses may be necessary for certain isolates of Pseudomonas aeruginosa. Contact manufacturer to discuss.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5 mg/kg per day PO | PO | q24h or divided q12h | At least 2-3 days beyond cessation of clinical signs, max 30 days | 🌎 NA |
| Hemoplasmosis | 5-10 mg/kg PO | PO | q24h | 14 days | 🌎 NA |
| Susceptible infections | 5 mg/kg | SC | q24h | Not specified | 🌍 EU |
| Susceptible infections | 2.5 mg/kg | PO | q12h | Not specified | 🌍 EU |
| Susceptible infections | 5 mg/kg | PO | q24h | Not specified | 🌍 EU |
- Susceptible infections: Do not exceed 5 mg/kg/day due to risk of blindness.
- Susceptible infections: Do not exceed 5 mg/kg/day due to risk of irreversible retinal blindness.
- Susceptible infections: Do not exceed 5 mg/kg/day total.
- Susceptible infections: Do not exceed 5 mg/kg/day total.
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Pasteurella upper respiratory infections in rabbits | 15-20 mg/kg PO | PO | q12h | Minimum 14 days to several months | 🌎 NA |
| Pasteurella in rabbits | 5 mg/kg PO, SC, IM or IV | PO, SC, IM, IV | q12h | 14 days | 🌎 NA |
| Susceptible infections in hedgehogs | 5-10 mg/kg PO or SC | PO, SC | q12h | — | 🌎 NA |
| Susceptible infections in chinchillas | 5-10 mg/kg PO, IM | PO, IM | q12h | — | 🌎 NA |
| Mycoplasmal pneumonia in mice and rats | 10 mg/kg PO | PO | q12h | — | 🌎 NA |
| Susceptible infections in Chinchillas, Gerbils, Guinea Pigs, Hamsters, Mice, Rats | 5-10 mg/kg PO or IM q12h or 5-20 mg/kg PO or SC q24h | PO, IM, SC | q12h or q24h | — | 🌎 NA |
| Susceptible infections in Chinchillas, Gerbils, Guinea Pigs, Hamsters, Mice, Rats (Drinking water) | 50-200 mg/liter | PO | Continuous | 14 days | 🌎 NA |
| Chronic respiratory disease in rats | 10-25 mg/kg PO | PO | q12h | — | 🌎 NA |
- Pasteurella upper respiratory infections in rabbits: First dose may be SC, do NOT give subsequent doses SC.
- Pasteurella in rabbits: If giving SC, dilute or skin may slough.
- Mycoplasmal pneumonia in mice and rats: Given with doxycycline.
- Susceptible infections in Chinchillas, Gerbils, Guinea Pigs, Hamsters, Mice, Rats: Do not use in young animals.
- Chronic respiratory disease in rats: If using theophylline concurrently, reduce theophylline dose by 30%.
Ferrets
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 10-20 mg/kg PO, IM, SC | PO, IM, SC | q12h | — | 🌎 NA |
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Empirical treatment in stable, immunocompetent Psittacines | 20 mg/kg PO | PO | q24h | — | 🌎 NA |
| Debilitated immunocompetent Psittacines | 15-20 mg/kg SC in fluid pocket | SC | q24h | — | 🌎 NA |
| Debilitated, immunocompromised Psittacines | 15-20 mg/kg SC in fluid pocket | SC | q12h | — | 🌎 NA |
| Susceptible infections in Ratites | 1.5-2.5 mg/kg PO or SC | PO, SC | q12h | — | 🌎 NA |
| Susceptible infections in Ratites (Drinking water) | 10% solution, 10 mg/kg | PO | Daily | 3 days | 🌎 NA |
| Susceptible infections in Ratites (IM) | 5 mg/kg IM | IM | q12h | 2 days | 🌎 NA |
- Empirical treatment in stable, immunocompetent Psittacines: Given with amoxicillin/clavulanate.
- Susceptible infections in Ratites (IM): IM injections cause severe muscle necrosis.
Reptiles
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible respiratory infections for most species | 5 mg/kg IM | IM | Every 5 days | 25 days | 🌎 NA |
| Chronic respiratory infections in tortoises | 15 mg/kg IM | IM | Every 72 hours | 5-7 treatments | 🌎 NA |
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5 mg/kg IV q24h; 5-7.5 mg/kg PO q24h | IV, PO | q24h | — | 🌎 NA |
| Susceptible respiratory infections | 7.5 mg/kg PO or IV | PO, IV | q24h | — | 🌎 NA |
| Susceptible infections (using compounded gel) | 7.5 mg/kg PO | PO | q24h | — | 🌎 NA |
- Susceptible infections: Use in horses is controversial. Only use in adults when other antibiotics are inappropriate.
- Susceptible infections (using compounded gel): Fast for 11-14 hours prior and 1-2 hours after dosing. Rinse mouth with water after dosing.
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Bovine respiratory disease | 2.5-5 mg/kg SC once daily for 3-5 days or 7.5-12.5 mg/kg SC once | SC | q24h or single dose | 3-5 days or once | 🌎 NA |
- Bovine respiratory disease: Not for dairy cattle or veal calves. 28-day slaughter withdrawal. Extra-label use prohibited.
Sheep
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections in alpacas (Camelids) | 5 mg/kg SC or 10 mg/kg PO | SC, PO | q24h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Enrofloxacin is a broad-spectrum, concentration-dependent fluoroquinolone antibiotic developed exclusively for veterinary use.
- Spectrum of Activity: Highly effective against a wide range of Gram-negative bacilli (e.g., Pseudomonas aeruginosa, E. coli, Klebsiella, Salmonella) and many Gram-positive cocci (e.g., Staphylococcus spp., including methicillin-resistant strains).
- Limitations: It has weak activity against anaerobes and variable efficacy against Streptococcus spp.
- Clinical Pearl: Enrofloxacin is highly lipophilic, allowing for excellent tissue penetration. It achieves therapeutic concentrations in difficult-to-reach sites such as the prostate, bone, cerebrospinal fluid (CSF), and intracellular compartments (e.g., inside macrophages), making it highly effective for deep-seated and intracellular infections.
Mechanism of action
Enrofloxacin exerts its rapid bactericidal effect by targeting key bacterial enzymes involved in DNA replication and transcription:
- Inhibits DNA gyrase (Topoisomerase II) → prevents the negative supercoiling of bacterial DNA required for replication.
- Inhibits Topoisomerase IV → interferes with the separation of interlinked replicated DNA molecules.
Result: Disruption of DNA synthesis → double-strand DNA breaks → rapid bacterial cell death within 20-30 minutes of exposure.
Pharmacodynamic Pearl: Enrofloxacin exhibits a significant post-antibiotic effect (PAE) for both Gram-negative and Gram-positive bacteria, meaning bacterial growth continues to be suppressed even after drug concentrations fall below the Minimum Inhibitory Concentration (MIC).
Safety & warnings
Contraindications
- Small and medium breed dogs 2 to 8 months of age (risk of cartilage damage)
- Large and giant breed dogs during their rapid-growth phase (may extend past 8 months)
- Patients hypersensitive to quinolones
- Foals (highly susceptible to arthropathic effects)
- Food-producing animals (extra-label use is strictly prohibited by the FDA)
- Dairy cattle or veal calves
- Growing dogs (<1 year of age; large-breed dogs <18 months of age)
- Cats <8 weeks of age
- Animals with known seizure disorders (relative contraindication)
Adverse effects
- Gastrointestinal distress (vomiting, anorexia, diarrhea)
- CNS stimulation (seizures, depression, lethargy, nervousness, ataxia)
- Cartilage abnormalities in young, growing animals
- Ocular toxicity/blindness in cats (at doses >5 mg/kg/day)
- Crystalluria (especially in dehydrated patients)
- Hypersensitivity reactions
- Elevated hepatic enzymes
- Tissue damage or pain at injection site (especially SC)
- Irreversible retinal blindness (cats)
- Cartilage abnormalities (growing dogs)
- Gastrointestinal upset (vomiting, diarrhea, anorexia)
- CNS toxicity / seizures (especially at high doses or with NSAIDs)
Precautions
Use with caution in patients with seizure disorders due to potential CNS stimulation.
Ensure patients remain well-hydrated to prevent crystalluria.
Patients with severe renal or hepatic impairment may require dosage adjustments to prevent drug accumulation.
Intravenous Administration Risks: Rapid or undiluted IV administration in dogs increases the risk of cardiac arrhythmias, hypotension, vomiting, and mast cell degranulation. Do not mix injectable enrofloxacin with any IV solution containing magnesium (e.g., Normosol-R, Plasmalyte) as micro-precipitants can lodge in the lungs, causing morbidity or mortality.
Feline Precautions: Doses exceeding 5 mg/kg/day in cats are associated with severe ocular toxicity, including irreversible retinal degeneration and blindness.
Drug interactions
Cations bind to enrofloxacin and prevent its absorption; separate doses by at least 2 hours.
Synergism may occur, though unpredictable against some bacteria like Pseudomonas aeruginosa.
May exacerbate nephrotoxicity and reduce the metabolism of systemic cyclosporine.
Increases the AUC and elimination half-life of both enrofloxacin and flunixin in dogs.
Severe hypoglycemia is possible.
Decreased enrofloxacin absorption; separate doses by at least 2 hours.
Increased methotrexate levels possible, resulting in toxicity.
May antagonize the antimicrobial activity of fluoroquinolones; concomitant use is not recommended.
May alter phenytoin blood levels.
Blocks tubular secretion of ciprofloxacin (active metabolite), increasing its blood level and half-life.
Increased risk for cardiotoxicity.
May inhibit absorption of enrofloxacin; separate doses by at least 2 hours.
May increase theophylline blood levels (by about 30-50% in dogs).
Potential for increased warfarin effects.
Binds fluoroquinolones, preventing GI absorption
Inhibits absorption (separate dosing by at least 2 hours)
May reduce the clearance of fluoroquinolones
Decreases metabolism and increases nephrotoxicity of ciclosporin
Decreases metabolism and increases nephrotoxicity of tacrolimus
Potentiates CNS adverse effects (seizure risk)
May increase the action of anticoagulants
Monitoring
- Clinical efficacy (resolution of infection)
- Adverse effects (GI upset, CNS signs)
- In cats: Monitor closely for mydriasis (dilated pupils) and/or retinal changes/vision loss
- Vision and pupillary light reflexes in cats
- Neurological status, especially in patients with a history of seizures
- Joint pain or lameness in young animals (if inadvertently administered)
Pharmacokinetics
Half-life
Absorption
Well absorbed after oral administration in most species. In dogs, oral bioavailability is ~80% (twice that of ciprofloxacin). Horses: 60-80%. Sheep: 65-75%. Peak levels (Cmax) occur within 1 hour of dosing. Food may delay the rate but not the extent of absorption.
Distribution
Widely distributed throughout the body. Volume of distribution (Vd) in dogs is ~3-4 L/kg. Only ~27% bound to canine plasma proteins. Concentrates in macrophages, bile, kidney, liver, lungs, and reproductive system (prostate). Therapeutic levels attained in bone, synovial fluid, skin, muscle, aqueous humor, and pleural fluid. Low concentrations in CSF (6-10% of serum levels).
Metabolism
Metabolized to various metabolites. Approximately 10-40% of circulating enrofloxacin is metabolized to the active compound ciprofloxacin in most species (dogs, cats, adult horses, cattle, turtles, snakes). Foals, pigs, and some lizards do not convert much enrofloxacin to ciprofloxacin.
Elimination
Eliminated via both renal (tubular secretion and glomerular filtration) and non-renal (feces/hepatic) mechanisms. Approximately 15-50% is eliminated unchanged in the urine.
Overdose
Acute overdoses in dogs typically result in gastrointestinal signs (anorexia, vomiting). Dogs receiving 10X the labeled dose for 14 days developed only vomiting and anorexia. However, extreme overdoses (25X the labeled rate for 11 days) resulted in death.
In cats, overdoses can be severe and irreversible. Doses of 20 mg/kg or more can cause retinopathy, blindness, and seizures.
Common signs of toxicity reported to poison control include vomiting, lethargy, seizures, anorexia, depression, and diarrhea in dogs; and seizures and recumbency in cats.
Available products
Formulations
- Tablets (film-coated)
- Oral taste tablets
- Injectable solution (2.27% for small animals, 10% for large animals)
- Compounded oral suspension or gel
- Injectable: 25 mg/ml, 50 mg/ml
- Oral tablets: 15 mg, 50 mg, 100 mg, 150 mg, 200 mg, 250 mg
- Oral solution: 25 mg/ml
Veterinary
- Enrofloxacin Tablets (Film-Coated) & Oral Taste Tablets: 22.7 mg, 68 mg, 136 mg (Baytril)
- Enrofloxacin Injection: 22.7 mg/mL (2.27%) in 20 mL vials (Baytril)
- Enrofloxacin Injection: 100 mg/mL (10%) in 100 mL and 250 mL bottles (Baytril 100)
- Enrocare
- Enrotron
- Enroxil
- Fenoflox
- Floxabactin
- Powerflox
- Quinoflox
- Xeden
- Zobuxa
Human-labeled
- None
Regulatory status
POM-V. Subject to strict antimicrobial stewardship guidelines.
POM-V
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored in tight containers at temperatures less than 30°C and protected from strong UV light. The 2.27% injection should be protected from light and not frozen. The 10% cattle injection should be protected from sunlight, not refrigerated or frozen, and stored below 40°C (104°F). If exposed to cold, precipitation may occur; warm and shake to redissolve.
Client information
Important Note for Cat Owners: Never exceed the dose prescribed by your veterinarian. High doses in cats can cause permanent blindness. If you notice your cat's pupils are unusually large or they seem to have trouble seeing, stop the medication immediately and contact your vet.
- Administration: Give this medication on an empty stomach if possible. However, if it causes your pet to vomit or feel sick, you can give it with a small amount of food.
- Handling Tablets: Do not crush the film-coated tablets. The medication inside is extremely bitter, and crushing it will likely cause your pet to refuse it or drool excessively.
- Hydration: Ensure your pet has access to plenty of fresh water at all times while on this medication to prevent crystals from forming in their urine.
- Puppies/Kittens: This drug is generally not used in young, growing animals as it can interfere with normal joint and cartilage development.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.