# Nitrofurantoin: veterinary dose and monograph

> Nitrofurantoin is a veterinary antibiotic. Nitrofuran urinary antiseptic concentrated in urine to therapeutic levels while plasma/tissue levels stay sub-therapeutic — therefore strictly a treatment for LOWER urinary tract infection (cystitis), never for pyelonephritis, prostatitis… Indications include lower urinary tract infection / bacterial cystitis (dogs, cats); multidrug-resistant uropathogen UTI (susceptibility-guided second line); enterococcal lower UTI. This monograph lists 4 reference doses for dogs, cats and horses, each with route, frequency and source.

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

## At a glance

- **Drug class:** Antibiotic
- **Also known as:** Niftran, Macrodantin, Furadantin
- **Species with doses:** Dogs, Cats and Horses
- **General dose range:** 4–5 mg/kg PO q8h — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Lower urinary tract infection / bacterial cystitis (dogs, cats)
- Multidrug-resistant uropathogen UTI (susceptibility-guided second line)
- Enterococcal lower UTI

## Nitrofurantoin 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

*Nitrofurantoin doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Lower UTI / cystitis | 4–5 mg/kg | PO | q8h | 7–14 days |
| Recurrent UTI prophylaxis (after cure) | 3–4 mg/kg | PO | q24h at bedtime, after urinating | — |

- Lower UTI / cystitis: Papich 5e: 4 mg/kg q8h PO or 2 mg/kg q6h PO (macrocrystals with food preferred). Plumb’s p.893: 4 mg/kg q8h (Polzin); 4 mg/kg q6–8h (Brovida); 5 mg/kg q8h (Dowling); 4.4 mg/kg three times daily (Senior). Urinary tract only — no systemic levels; avoid in renal failure.
- Recurrent UTI prophylaxis (after cure): Plumb’s p.893: 3–4 mg/kg PO once daily at night after the last urination (Polzin & Osborne; Adams 2009) — only after the existing infection is fully treated and underlying causes investigated. Rarely hepatopathy.

### Cats

*Nitrofurantoin doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Lower UTI / cystitis | 4–5 mg/kg | PO | q8h | 7–14 days |

- Lower UTI / cystitis: Papich 5e: 4 mg/kg q8h PO or 2 mg/kg q6h PO. Plumb’s p.893: 5 mg/kg PO q8h (Dowling); 4 mg/kg q6–8h; prophylaxis 3–4 mg/kg once daily at night after cure.

### Horses

*Nitrofurantoin doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Urinary tract infection | 2–4.5 mg/kg | PO | q8h | — |

- Urinary tract infection: Papich 5e: 2 mg/kg q8h PO. Plumb’s p.893: 2.5–4.5 mg/kg PO three times daily (Robinson 1987) or 10 mg/kg PO daily (Huber 1988).

## Contraindications

Renal insufficiency (reduced urinary concentration → ineffective + systemic toxicity). Upper UTI / pyelonephritis / prostatitis / bacteraemia. Anuria/oliguria. Known hypersensitivity. NOT for food animals (nitrofurans are banned in food-producing species in India, EU and many countries — possible carcinogen).

## Species-specific warnings

> **Caution:** Cattle: PROHIBITED in food-producing animals — nitrofurans are a banned residue class (carcinogenic concern) in India, EU and elsewhere.

> **Caution:** Cats: Cats may be more sensitive to GI upset and oxidative effects — dose carefully and keep courses short.

## Adverse effects

- GI: nausea, vomiting, anorexia (give with food)
- Hepatotoxicity (uncommon, idiosyncratic)
- Peripheral neuropathy on prolonged use
- Pulmonary reactions (rare, immune-mediated — chronic use)
- Brown discolouration of urine (harmless)
- Haemolysis in G6PD-type oxidative susceptibility

## Drug interactions

- Antacids containing magnesium trisilicate: reduce absorption
- Probenecid / sulfinpyrazone: decrease urinary excretion → less efficacy, more systemic toxicity
- Quinolones: in-vitro antagonism — avoid combining
- Drugs that alkalinise urine may reduce activity

## Pregnancy and lactation

Generally acceptable for lower UTI in pregnancy in small animals; avoid near term in oxidative-stress-susceptible neonates. Not used in food animals at all.

## Monitoring

- Urine culture before and after therapy (confirm cure)
- Renal function — do not use if azotaemic
- Neurological signs / limb weakness on prolonged courses
- Liver enzymes if therapy extended
- Hydration / urine output (needs good urine flow to work)

## Toxicity and overdose

Acute overdose: GI upset predominates. Chronic toxicity is the concern — dose-related peripheral neuropathy, idiosyncratic hepatotoxicity, and rare immune-mediated pulmonary fibrosis with long-term use. Accumulates dangerously in renal failure. Nitrofurans are also a regulatory hazard (banned residue class in food animals).

Management: No specific antidote. Supportive — fluids, anti-emetic, maintain renal output. Discontinue for any sign of neuropathy or pulmonary/hepatic reaction. Most acute overdoses resolve with symptomatic care.

## Clinical pearls

- A urine-only antibiotic: brilliant for resistant cystitis, useless for kidney or prostate infection
- Give with food to cut nausea and improve absorption
- Excellent stewardship choice — low cross-resistance preserves it as a second-line uropathogen drug
- Never use in food animals — nitrofuran residues are prohibited (carcinogenicity concern) in India and globally
- Don't combine with fluoroquinolones (in-vitro antagonism) or use when GFR is low (loses urinary concentration)

## Mechanism of action

A pro-drug reduced inside bacteria by flavoproteins (nitrofuran reductases) to reactive intermediates that damage bacterial ribosomal proteins, DNA, and multiple enzyme systems simultaneously — this multi-target attack is why acquired resistance is slow to develop. Bactericidal in concentrated urine; ineffective at the low concentrations found in blood/tissue.

## Formulations and products

- 50 mg tablet/capsule
- 100 mg tablet/capsule
- Oral suspension 5 mg/mL (25 mg/5 mL)
- (No food-animal vet products — banned residue class) (—) — —, Use human-label small-animal only
- Niftran — 50 / 100 mg capsule, Capsule (human-label)
- Nitrofurantoin — 50 / 100 mg tablet, Tablet (human-label)

## Storage

Tablets/capsules: 15–30 °C, protect from light (darkens) and moisture. Suspension: per label, shake well.

## 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

- [Meropenem](https://vetmasterji.com/drugs/meropenem)
- [Minocycline](https://vetmasterji.com/drugs/minocycline)
- [Mupirocin](https://vetmasterji.com/drugs/mupirocin)
- [Neomycin](https://vetmasterji.com/drugs/neomycin)
- [Norfloxacin](https://vetmasterji.com/drugs/norfloxacin)
- [Orbifloxacin](https://vetmasterji.com/drugs/orbifloxacin)
- [Ornidazole](https://vetmasterji.com/drugs/ornidazole)
- [Oxytetracycline](https://vetmasterji.com/drugs/oxytetracycline)

## Frequently asked questions

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

Reference doses for Nitrofurantoin in dogs: 4–5 mg/kg PO q8h for 7–14 days (Lower UTI / cystitis); 3–4 mg/kg PO q24h at bedtime, after urinating (Recurrent UTI prophylaxis (after cure)). Confirm against the label and the patient before use.

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

Reference doses for Nitrofurantoin in cats: 4–5 mg/kg PO q8h for 7–14 days (Lower UTI / cystitis). Confirm against the label and the patient before use.

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

Reference doses for Nitrofurantoin in horses: 2–4.5 mg/kg PO q8h (Urinary tract infection). Confirm against the label and the patient before use.

### When should Nitrofurantoin not be used?

Renal insufficiency (reduced urinary concentration → ineffective + systemic toxicity). Upper UTI / pyelonephritis / prostatitis / bacteraemia. Anuria/oliguria. Known hypersensitivity. NOT for food animals (nitrofurans are banned in food-producing species in India, EU and many countries — possible carcinogen).

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

GI: nausea, vomiting, anorexia (give with food); Hepatotoxicity (uncommon, idiosyncratic); Peripheral neuropathy on prolonged use; Pulmonary reactions (rare, immune-mediated — chronic use); Brown discolouration of urine (harmless); Haemolysis in G6PD-type oxidative susceptibility.

## 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.