Marbofloxacin
Ro 9-1168
Also known as: Zeniquin · Marbocyl · Aurizon · Efex · Marbocare · Ro 9-1168 · Marbofloxacine · Marbofloxacinum · Marbofloxacino
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 |
|---|---|---|---|---|---|
| For susceptible infections (urinary tract, skin and soft tissue) | 2.75-5.5 mg/kg PO once daily | PO | q24h | Give for 2-3 days beyond cessation of clinical signs (skin/soft tissue); at least 10 days (urinary tract). Max 30 days. | 🌎 NA |
| For susceptible Pseudomonas otitis | 5.5 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Susceptible bacterial infections | 2 mg/kg | IV/SC/PO | q24h | Not specified | 🌍 EU |
| Otitis externa | 10 drops per ear | topical | sid | Not specified | 🌍 EU |
- For susceptible infections (urinary tract, skin and soft tissue): If no improvement noted after 5 days, reevaluate diagnosis.
- For susceptible Pseudomonas otitis: Dose at the high end of the flexible dosing label for severe/chronic cases or when topical therapy is not possible.
- Susceptible bacterial infections: Higher doses should be considered for certain sites, including prostatitis, and for certain isolates of Pseudomonas aeruginosa.
- Otitis externa: Using compound aural preparation.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| For susceptible infections (urinary tract, skin and soft tissue) | 2.75-5.5 mg/kg PO once daily | PO | q24h | Give for 2-3 days beyond cessation of clinical signs (skin/soft tissue); at least 10 days (urinary tract). Max 30 days. | 🌎 NA |
| First-line treatment for feline tuberculosis or non-tuberculous mycobacteria (NTM) | 2 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| For hemoplasmosis | 2.75 mg/kg PO once daily (q24h) | PO | q24h | — | 🌎 NA |
| Susceptible bacterial infections | 2 mg/kg | IV/SC/PO | q24h | Not specified | 🌍 EU |
- For susceptible infections (urinary tract, skin and soft tissue): If no improvement noted after 5 days, reevaluate diagnosis.
- First-line treatment for feline tuberculosis or non-tuberculous mycobacteria (NTM): Pending definitive diagnosis. Not effective against MAC infection.
- Susceptible bacterial infections: Do not use 20 mg or 80 mg tablets. May allow clearance of Mycoplasma haemofelis in persistently infected cats.
Reptiles
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 10 mg/kg PO at least every 48 hours | PO | q48h | — | 🌎 NA |
- Susceptible infections: Study done in Ball pythons (Python regius). Further studies required to determine effective doses and toxicity.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Marbofloxacin is a synthetic, broad-spectrum fluoroquinolone antibiotic used primarily in veterinary medicine. It exhibits concentration-dependent bactericidal activity and a significant post-antibiotic effect (PAE) for both gram-negative and gram-positive bacteria. It is active in both stationary and growth phases of bacterial replication.
- Spectrum of Activity: Highly effective against a wide range of gram-negative bacilli and cocci (e.g., Pseudomonas aeruginosa, E. coli, Klebsiella, Enterobacter, Proteus, Salmonella) and some gram-positive organisms (e.g., Staphylococcus spp., including penicillinase-producing strains).
- Clinical Pearl: Like other fluoroquinolones, marbofloxacin has weak activity against most anaerobes and variable/poor efficacy against Streptococcus species. It is not recommended for anaerobic or streptococcal infections.
- Resistance: Occurs primarily via chromosomal mutation (especially in Pseudomonas, Klebsiella, and Enterococci); plasmid-mediated resistance is rare.
Mechanism of action
Marbofloxacin exerts its bactericidal effect by targeting key bacterial enzymes involved in DNA replication and transcription:
- Inhibits DNA-gyrase (topoisomerase II) → prevents DNA supercoiling.
- Inhibits Topoisomerase IV → prevents separation of interlinked daughter DNA molecules.
- Result: Disruption of DNA replication, transcription, and repair → rapid bacterial cell death (typically within 20-30 minutes of exposure).
Safety & warnings
Contraindications
- Hypersensitivity to fluoroquinolones
- Small and medium breed dogs up to 8 months of age
- Large breed dogs up to 12 months of age
- Giant breed dogs up to 18 months of age
- Cats under 12 months of age
- Food-producing animals (FDA prohibited)
- Cats (do not use 20 mg and 80 mg tablets)
- Dogs < 12 months of age
- Giant-breed dogs < 18 months of age
- Cats < 16 weeks of age
Adverse effects
- Gastrointestinal distress (vomiting, anorexia, soft stools, diarrhea)
- Decreased activity/lethargy
- Cartilage abnormalities in young, growing animals
- Elevated hepatic enzymes (rare)
- Ataxia, seizures, depression, nervousness (rare)
- Hypersensitivity reactions (rare)
- Crystalluria (rare)
- Potential ocular toxicity/blindness in cats (rare/unproven, but reported)
- Gastrointestinal signs (nausea, vomiting)
- Potential CNS toxicity (seizures)
- Cartilage abnormalities in growing animals
- Potential retinal toxicity/blindness in cats (at high doses)
Precautions
Warning: Contraindicated in young, growing animals due to the risk of articular cartilage lesions (arthropathy).
- Neurologic: Can rarely cause CNS stimulation; use with caution in patients with pre-existing seizure disorders.
- Renal/Hepatic: Use cautiously in patients with severe hepatic or renal insufficiency.
- Hydration: Ensure adequate hydration to minimize the risk of crystalluria.
- Regulatory: The FDA strictly prohibits the extra-label use of fluoroquinolones in food-producing animals.
Drug interactions
Cations (Mg++, Al+++, Ca++) may bind to marbofloxacin and prevent its absorption; separate doses by at least 2 hours
Unpredictable synergism may occur against some bacteria, particularly Pseudomonas aeruginosa
May exacerbate nephrotoxicity and reduce the metabolism of systemically used cyclosporine
May increase AUC and elimination half-life of the fluoroquinolone, and vice versa (extrapolated from enrofloxacin)
Severe hypoglycemia possible
Decreased marbofloxacin absorption; separate doses by at least two hours
Increased MTX levels possible with resultant toxicity
May antagonize the antimicrobial activity of fluoroquinolones; concomitant use not recommended
Marbofloxacin may alter phenytoin levels
Blocks tubular secretion and may increase blood level and half-life of marbofloxacin
Increased risk for cardiotoxicity
May inhibit absorption of marbofloxacin; separate doses by at least 2 hours
May increase theophylline blood levels (though less likely than with enrofloxacin)
Potential for increased warfarin effects
Bind fluoroquinolones, preventing GI absorption
Inhibits absorption (separate dosing by at least 2 hours)
May reduce the clearance of fluoroquinolones
May decrease metabolism and increase nephrotoxicity
May decrease metabolism and increase nephrotoxicity
May increase anticoagulant action
May potentiate CNS adverse effects (seizures)
Monitoring
- Clinical efficacy (resolution of infection)
- Adverse effects (GI distress, CNS signs)
- Joint health/lameness in younger animals (if inadvertently used)
- Clinical efficacy and resolution of infection
- Culture and susceptibility results
- Signs of gastrointestinal upset
- Neurological signs (especially in patients with a history of seizures)
- Vision changes or mydriasis in cats
Pharmacokinetics
Half-life
Absorption
Dogs: Rapidly absorbed after oral administration with 94% bioavailability; peak plasma levels in ~1.5 hours. Cats: Absorption is nearly complete; peak serum levels in 1-2 hours.
Distribution
Dogs: Apparent volume of distribution is 1.2-1.9 L/kg. Protein binding is low.
Metabolism
Dogs: Only about 15% of a dose is metabolized in the liver.
Elimination
Dogs: Eliminated unchanged in the urine (40%) and bile/feces.
Overdose
Acute overdoses of marbofloxacin are unlikely to result in signs more serious than anorexia or vomiting, though other adverse effects (like CNS stimulation) could theoretically occur.
- Chronic Toxicity: In safety studies, dogs receiving massive overdoses (55 mg/kg per day for 12 days) developed anorexia, vomiting, dehydration, tremors, red skin, facial swelling, lethargy, and weight loss.
- Treatment: Management of overdose consists of drug withdrawal and symptomatic/supportive care. If ingestion was recent, gastrointestinal decontamination (emesis or activated charcoal) may be considered.
Available products
Formulations
- Oral tablets
- Injectable: 200 mg powder for reconstitution (10 mg/ml)
- Oral: 5 mg, 20 mg, 80 mg tablets
- Topical: 3 mg/ml aural drops (compound with clotrimazole and dexamethasone)
Veterinary
- Marbofloxacin Oral Tablets: 25 mg, 50 mg, 100 mg, 200 mg (Zeniquin)
- Actimarbo
- Aurizon
- Efex
- Marbocare
- Marbocyl
- Marbodex
- Marbotab
- Marboxidin
- Marfloquin
- NorOtic
- Quiflor
- Softiflox
- Ubiflox
Regulatory status
POM-V classification.
POM-V classification.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Marbofloxacin tablets should be stored below 30°C (86°F).
Client information
- Complete the Course: Give the medication exactly as prescribed by your veterinarian. Do not stop treating just because your pet appears well; stopping early can lead to resistant bacterial infections.
- Administration: Can be given with or without food. If vomiting occurs, try giving it with a small treat or meal.
- Avoid Dairy and Supplements: Do not give this medication at the same time as dairy products (cheese, milk), antacids, or iron/zinc supplements. These can bind to the drug and prevent it from working. Separate these by at least 2 hours.
- Watch for Side Effects: Contact your veterinarian if you notice severe vomiting, diarrhea, loss of appetite, or unusual behavior (such as tremors, incoordination, or sudden lethargy).
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.