# Rifampin: veterinary dose and monograph

> Rifampin is a veterinary antibiotic. Lipophilic antibiotic that inhibits bacterial RNA polymerase — penetrates abscesses, intracellular sites and biofilm exceptionally well. Indications include rhodococcus equi pneumonia in foals (with a macrolide); resistant / deep canine staphylococcal pyoderma (combination); adjunct for intracellular / granulomatous infections. This monograph lists 5 reference doses for dogs, cats, horses and birds, each with route, frequency and source.

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

## 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

*Rifampin doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Resistant staph / granulomatous infection (combination) | 5–10 mg/kg | PO | q12–24h with a second agent; monitor LFTs | — |
| Atypical mycobacteria / staph endocarditis / actinomycosis (combination) | 10–20 mg/kg | PO | q8–12h | — |

- 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

*Rifampin doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection (combination therapy) | 5–10 mg/kg | PO | q12h (5 mg/kg) or q24h (10 mg/kg) | — |

- 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

*Rifampin doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| R. equi pneumonia (foal, with macrolide) | 5–10 mg/kg | PO | q12–24h, combined with azithromycin / clarithromycin / erythromycin | — |

- 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

*Rifampin doses for birds*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Mycobacteriosis (multi-drug) | 45 mg/kg | PO | q24h | — |

- 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

> **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

- [Pirlimycin](https://vetmasterji.com/drugs/pirlimycin)
- [Polymyxin B](https://vetmasterji.com/drugs/polymyxin-b)
- [Pradofloxacin](https://vetmasterji.com/drugs/pradofloxacin)
- [Procaine Penicillin G](https://vetmasterji.com/drugs/procaine-penicillin)
- [Rifaximin](https://vetmasterji.com/drugs/rifaximin)
- [Silver Sulfadiazine](https://vetmasterji.com/drugs/silver-sulfadiazine)
- [Spectinomycin](https://vetmasterji.com/drugs/spectinomycin)
- [Streptomycin (Dihydrostreptomycin)](https://vetmasterji.com/drugs/streptomycin)

## Frequently asked questions

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

Reference doses for Rifampin in dogs: 5–10 mg/kg PO q12–24h with a second agent; monitor LFTs (Resistant staph / granulomatous infection (combination)); 10–20 mg/kg PO q8–12h (Atypical mycobacteria / staph endocarditis / actinomycosis (combination)). Confirm against the label and the patient before use.

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

Reference doses for Rifampin in cats: 5–10 mg/kg PO q12h (5 mg/kg) or q24h (10 mg/kg) (Susceptible infection (combination therapy)). Confirm against the label and the patient before use.

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

Reference doses for Rifampin in horses: 5–10 mg/kg PO q12–24h, combined with azithromycin / clarithromycin / erythromycin (R. equi pneumonia (foal, with macrolide)). Confirm against the label and the patient before use.

### When should Rifampin not be used?

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

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

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

## Sources

- Plumb's Veterinary Drug Handbook
- 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.