Rifampin: veterinary dose and monograph

At a glance

Drug class

Antibiotic

Also known as

Rifampicin, Rifadin

Species with doses

Dogs, Cats, Horses and Birds

General dose range

5–10 mg/kg PO q12–24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Rhodococcus equi pneumonia in foals (with a macrolide)
• Resistant / deep canine staphylococcal pyoderma (combination)
• Adjunct for intracellular / granulomatous infections

Rifampin 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

• Resistant staph / granulomatous infection (combination): Papich 5e: 5 mg/kg q12h or 10 mg/kg q24h PO (twice daily preferred). Plumb’s p.1043: scarred pyogranulomatous pyoderma 5–10 mg/kg PO q24h with a second antibiotic for 4–8 weeks (Rosenkrantz 2009). Always combine with another antibiotic; CBC, liver panel and urinalysis every 2–3 weeks. Colours urine and tears red-orange.
• Atypical mycobacteria / staph endocarditis / actinomycosis (combination): Plumb’s p.1043: 10–20 mg/kg PO q8–12h with amoxicillin-clavulanate or trimethoprim-sulfa (Trepanier 1999); actinomycosis 10–20 mg/kg q12h (Hardie 1984). Hepatotoxic at higher doses — monitor liver enzymes.

Cats

• Susceptible infection (combination therapy): Papich 5e (dogs and cats): 5 mg/kg q12h or 10 mg/kg q24h PO. Always combine with another antimicrobial.

Horses

• R. equi pneumonia (foal, with macrolide): Papich 5e: foals 5 mg/kg q12h PO (adult horses 10 mg/kg q24h). Plumb’s p.1043: 5 mg/kg PO twice daily or 10 mg/kg once daily, with erythromycin 25 mg/kg q6–8h or another macrolide, usually for 4–9 weeks (Giguere 2003). Never use alone — resistance develops rapidly.

Birds

• Mycobacteriosis (multi-drug): Plumb’s p.1043 (Pollock 2007): 45 mg/kg PO once daily with ethambutol 30 mg/kg once daily plus clofazimine 6 mg/kg or isoniazid 30 mg/kg once daily. Zoonotic considerations apply.

Contraindications

Hepatic impairment (hepatotoxic and strong hepatic enzyme inducer). Monotherapy (rapid resistance). Many drug interactions via CYP induction. Caution in pregnancy.

Adverse effects

• Hepatotoxicity (monitor liver enzymes)
• Harmless orange-red discolouration of urine, tears, saliva
• GI upset; anorexia

Drug interactions

• POTENT hepatic enzyme inducer — lowers plasma levels of many co-medications (azole antifungals, corticosteroids, digoxin, anticoagulants, methadone, theophylline) requiring dose adjustment
• Additive hepatotoxicity with other hepatotoxic drugs (e.g. azole antifungals)
• Antacids reduce absorption — give on an empty stomach

Pregnancy and lactation

Crosses the placenta and is teratogenic at high doses in laboratory animals — use in pregnancy only if essential.

Monitoring

• Liver enzymes (ALT / ALP) at baseline and during therapy
• Warn owners about orange-red staining of urine / tears (normal)
• Review co-medications — rifampin induces hepatic enzymes and lowers levels of many drugs

Toxicity and overdose

Dose-related hepatotoxicity is the key risk, alongside GI upset and a harmless orange-red discolouration of urine, tears and saliva. Its enzyme induction can render co-administered drugs sub-therapeutic.

Clinical pearls

• Never use as a single agent — pair it with a macrolide (foals) or another anti-staph drug (dogs) to prevent resistance
• Orange tears and urine are expected and harmless — tell the owner in advance
• Recheck liver values — hepatotoxicity is the main reason to stop

Mechanism of action

Inhibits bacterial DNA-dependent RNA polymerase (β-subunit), halting transcription → bactericidal. Highly lipophilic, penetrating abscesses, caseous lesions, intracellular sites and biofilm. Single-step polymerase mutation produces resistance rapidly, which is why it is always used in combination.

Formulations and products

• Rifampin 150 mg capsule
• Rifampin 300 mg capsule
• Rifadin — 150 / 300 mg, Capsule (human-label)
• R-Cin — 150 / 300 / 450 / 600 mg, Capsule / tablet (human-label)

Storage

Store capsules at 15–30 °C, dry and protected from light.

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

• Pirlimycin
• Polymyxin B
• Pradofloxacin
• Procaine Penicillin G
• Rifaximin
• Silver Sulfadiazine
• Spectinomycin
• Streptomycin (Dihydrostreptomycin)

Frequently asked questions