Orbifloxacin: veterinary dose and monograph

At a glance

Drug class

Antibiotic

Also known as

Orbax

Species with doses

Dogs, Cats and Horses

General dose range

2.5–7.5 mg/kg PO q24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Susceptible skin and soft-tissue infections / wounds (dogs and cats)
• Urinary tract infection (susceptible)
• Susceptible Gram-negative and some Gram-positive infections

Orbifloxacin dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Susceptible skin/soft-tissue/UTI: Papich 5e and Plumb’s p.911 (Orbax label): 2.5–7.5 mg/kg PO once daily — use the higher end for hospitalised patients, complicated UTI, foreign-body or compromised-tissue infections and problem pathogens. Avoid in growing dogs (cartilage). Separate from antacids, sucralfate and dairy.

Cats

• Susceptible infection: Papich 5e and Plumb’s p.911: tablets 2.5–7.5 mg/kg PO once daily; suspension 7.5 mg/kg (1 mL/kg) once daily for skin infections. Fluoroquinolone retinal toxicity is dose-related in cats — do not exceed the label dose.

Horses

• Susceptible infection: Papich 5e: 5 mg/kg PO q24h. Plumb’s p.911: 5 mg/kg (Davis 2006) or 7.5 mg/kg (Haines 2001) PO once daily. Avoid in foals (arthropathy).

Contraindications

Growing dogs (arthropathy — cartilage damage in juveniles). Seizure disorders (GABA antagonism). Cats — use the lower dose to limit retinal-toxicity risk (a fluoroquinolone class effect). Known fluoroquinolone hypersensitivity. Pregnancy where alternatives exist.

Species-specific warnings

Cats: Use the lower dose range — fluoroquinolones can cause dose-dependent retinal degeneration/blindness in cats.

Dogs: Avoid in growing large/giant-breed dogs (articular cartilage damage).

Adverse effects

• GI upset (vomiting, soft stool)
• Cartilage damage in growing animals
• CNS excitation/seizures (rare)
• Retinal degeneration in cats at higher doses (fluoroquinolone class)

Drug interactions

• Di-/tri-valent cations (antacids, sucralfate, dairy, iron/calcium): chelation reduces absorption — separate by ≥2 h
• Theophylline: reduced clearance → toxicity risk
• NSAIDs: additive CNS excitation (seizure risk)
• Warfarin: potentiated anticoagulation

Pregnancy and lactation

Avoid in pregnancy where alternatives exist (fetal arthropathy risk).

Monitoring

• Culture & sensitivity (stewardship) and clinical response
• Feline vision/pupillary responses
• CNS signs in epileptics; avoid in growing animals (joints)

Toxicity and overdose

Overdose: GI upset, CNS excitation/seizures, and (cats) dose-dependent retinal degeneration — a fluoroquinolone class effect, so keep feline doses low. Cartilage toxicity in juveniles. Generally a wide margin at label doses.

Management: No specific antidote. Decontaminate if recent large ingestion; IV fluids, control seizures with benzodiazepines; in cats, monitor vision/perform fundic exam. Supportive care; effects resolve with clearance.

Clinical pearls

• A convenient once-daily veterinary fluoroquinolone for susceptible skin/soft-tissue and urinary infections in dogs and cats
• Keep the dose at the LOW end in cats (fluoroquinolone retinal-toxicity concern) and avoid in growing dogs (arthropathy)
• Separate from antacids/sucralfate/dairy (chelation) and reserve via culture to protect the class
• Concentration-dependent — give the full daily dose once, not split

Mechanism of action

Inhibits bacterial DNA gyrase and topoisomerase IV, blocking DNA supercoiling/replication — rapid, concentration-dependent bactericidal killing with a post-antibiotic effect (efficacy tracks Cmax/MIC and AUC/MIC, favouring once-daily dosing). Broad Gram-negative and moderate Gram-positive activity; limited against anaerobes.

Formulations and products

• 5.7 / 22.7 / 68 mg tablet (Orbax)
• Oral suspension 30 mg/mL (cats/small dogs)
• Orbax (Merck Animal Health) — 5.7 / 22.7 / 68 mg tablet; 30 mg/mL suspension, Tablet / suspension

Storage

Tablets/suspension: 15–30 °C, dry, protect from light; shake suspension.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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• Mupirocin
• Neomycin
• Nitrofurantoin
• Norfloxacin
• Ornidazole
• Oxytetracycline
• Penicillin G
• Pirlimycin

Frequently asked questions