Norfloxacin: veterinary dose and monograph

At a glance

Drug class

Antibiotic

Also known as

Norflox, Noroxin, Norbactin

Species with doses

Dogs and Cats

General dose range

5–11 mg/kg PO q12–24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Lower urinary tract infection (Gram-negative)
• Bacterial enteritis / colibacillosis
• Poultry colibacillosis (water medication, where legally permitted)
• Susceptible Gram-negative soft-tissue infection (limited tissue penetration)

Norfloxacin 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

• UTI / enteric infection: Papich 5e: dogs and cats 22 mg/kg q12h PO. Not in Plumb’s. Mainly urinary concentrations; avoid in growing dogs. (The previous 5–11 mg/kg was below the reference.)

Cats

• UTI (susceptible organisms): Papich 5e: dogs and cats 22 mg/kg q12h PO.

Cattle

• Not recommended (food-animal fluoroquinolone): Papich 5e: no large-animal doses reported; not in Plumb’s.

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Not recommended (food-animal fluoroquinolone): Papich 5e: no large-animal doses reported; not in Plumb’s.

Birds

• Not recommended (food-animal fluoroquinolone): Papich 5e reports no large-animal or avian doses; not in Plumb’s. Verify local law before any use in food-producing birds.

Contraindications

Growing animals (arthropathy). Fluoroquinolone restrictions in food animals (verify legality — poultry fluoroquinolone use is banned/limited in many countries). Seizure disorders. Known hypersensitivity. Pregnancy where alternatives exist.

Species-specific warnings

Birds: Fluoroquinolone use in poultry is banned/restricted in many countries (resistance concerns) — verify legality before flock use.

Adverse effects

• GI upset
• Cartilage damage in growing animals
• CNS excitation/seizures (rare)
• Crystalluria in alkaline urine

Drug interactions

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

Pregnancy and lactation

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

Monitoring

• Urine culture (confirm cure for UTI)
• Renal function on prolonged use
• CNS signs in at-risk patients
• Legal compliance for any food-animal use

Toxicity and overdose

Overdose: GI upset, CNS excitation/seizures, crystalluria. Cartilage toxicity in juveniles (class effect). Generally less potent/penetrating than newer fluoroquinolones.

Management: No specific antidote. Decontaminate if recent ingestion; IV fluids to maintain urine flow and prevent crystalluria; control seizures with benzodiazepines. Supportive care.

Clinical pearls

• A cheap, widely available urinary/enteric fluoroquinolone — but its poor tissue penetration limits it to lower UTI and gut infections
• For systemic or deep infections, choose a newer fluoroquinolone (enrofloxacin, marbofloxacin, pradofloxacin)
• Separate from antacids/sucralfate/dairy by ≥2 h
• Be aware that poultry/food-animal fluoroquinolone use is restricted or banned in many jurisdictions

Mechanism of action

Inhibits bacterial DNA gyrase (and topoisomerase IV), blocking DNA supercoiling/replication — concentration-dependent bactericidal action. Its pharmacokinetics favour urinary and gut concentrations over systemic tissue levels, which defines its clinical niche.

Formulations and products

• 400 mg tablet
• Oral/water-soluble powder (poultry)
• Norflox — 400 mg tablet, Tablet (human-label)
• Norbactin — 400 mg tablet, Tablet (human-label)

Storage

Tablets/powder: 15–30 °C, protect from light and moisture. Medicated water: prepare fresh daily.

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.

Other antibiotics

• Minocycline
• Mupirocin
• Neomycin
• Nitrofurantoin
• Orbifloxacin
• Ornidazole
• Oxytetracycline
• Penicillin G

Frequently asked questions