# Orbifloxacin: veterinary dose and monograph

> Orbifloxacin is a veterinary antibiotic. A veterinary-licensed fluoroquinolone (Orbax) for dogs and cats — once-daily oral treatment of susceptible skin/soft-tissue infections, wounds, and urinary tract infections (broad Gram-negative and moderate Gram-positive cover). Indications include susceptible skin and soft-tissue infections / wounds (dogs and cats); urinary tract infection (susceptible); susceptible Gram-negative and some Gram-positive infections. This monograph lists 3 reference doses for dogs, cats and horses, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/orbifloxacin · Last reviewed: 2026-10-01

## 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

*Orbifloxacin doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible skin/soft-tissue/UTI | 2.5–7.5 mg/kg | PO | q24h | — |

- 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

*Orbifloxacin doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 2.5–7.5 mg/kg | PO | q24h | — |

- 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

*Orbifloxacin doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 5–7.5 mg/kg | PO | q24h | — |

- 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

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

> **Caution:** 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

> **Caution:** 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.

## Other antibiotics

- [Mupirocin](https://vetmasterji.com/drugs/mupirocin)
- [Neomycin](https://vetmasterji.com/drugs/neomycin)
- [Nitrofurantoin](https://vetmasterji.com/drugs/nitrofurantoin)
- [Norfloxacin](https://vetmasterji.com/drugs/norfloxacin)
- [Ornidazole](https://vetmasterji.com/drugs/ornidazole)
- [Oxytetracycline](https://vetmasterji.com/drugs/oxytetracycline)
- [Penicillin G](https://vetmasterji.com/drugs/penicillin-g)
- [Pirlimycin](https://vetmasterji.com/drugs/pirlimycin)

## Frequently asked questions

### What is the dose of Orbifloxacin for dogs?

Reference doses for Orbifloxacin in dogs: 2.5–7.5 mg/kg PO q24h (Susceptible skin/soft-tissue/UTI). Confirm against the label and the patient before use.

### What is the dose of Orbifloxacin for cats?

Reference doses for Orbifloxacin in cats: 2.5–7.5 mg/kg PO q24h (Susceptible infection). Confirm against the label and the patient before use.

### What is the dose of Orbifloxacin for horses?

Reference doses for Orbifloxacin in horses: 5–7.5 mg/kg PO q24h (Susceptible infection). Confirm against the label and the patient before use.

### When should Orbifloxacin not be used?

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.

### What are the side effects of Orbifloxacin in animals?

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

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.