# Neomycin: veterinary dose and monograph

> Neomycin is a veterinary antibiotic. Aminoglycoside used almost exclusively topically or orally — oral neomycin is essentially NOT absorbed from an intact gut, so it acts locally against enteric Gram-negatives and to reduce ammonia-producing flora in hepatic encephalopathy. Indications include bacterial enteritis / colibacillosis (oral, local gut action); hepatic encephalopathy — reduce ammoniagenic gut flora (oral); pre-operative gut decontamination. This monograph lists 12 reference doses for dogs, cats, cattle, horses, goats and sheep and 5 more species, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

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

## At a glance

- **Drug class:** Antibiotic
- **Also known as:** Neomycin sulphate, Nebasulf, Neosporin (combination)
- **Species with doses:** Dogs, Cats, Cattle, Horses, Goats, Sheep, Pigs, Birds, Ferrets, Guinea pigs and Chinchillas
- **General dose range:** 10–20 mg/kg PO q6–12h — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Bacterial enteritis / colibacillosis (oral, local gut action)
- Hepatic encephalopathy — reduce ammoniagenic gut flora (oral)
- Pre-operative gut decontamination
- Superficial bacterial skin, ear and eye infections (topical combinations)
- Mastitis / metritis (intramammary / intrauterine combination products)

## Neomycin 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

*Neomycin doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Enteric infection (local) | 10–20 mg/kg | PO | q6–12h | ≤5–7 days |
| Hepatic encephalopathy | 10–20 mg/kg | PO | q8–12h | — |

- Enteric infection (local): Papich 5e: 10–20 mg/kg q6–12h PO. Plumb’s p.883: campylobacteriosis 20 mg/kg PO q12h (Willard 2003). Not absorbed from the intact gut; avoid with GI ulceration or renal failure. Systemic (parenteral) use is very nephrotoxic.
- Hepatic encephalopathy: Plumb’s p.883: 20 mg/kg PO three times daily if lactulose and metronidazole are insufficient (Trepanier 2008); portosystemic shunts 10–20 mg/kg two to three times daily (Twedt 2009); 20 mg/kg q12h (Silverstein 2009); retention enema 15 mg/kg q6h. Combine with lactulose; avoid with GI bleeding or renal failure.

### Cats

*Neomycin doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Enteric infection / HE | 10–22 mg/kg | PO | q8–12h | — |

- Enteric infection / HE: Papich 5e: 10–20 mg/kg q6–12h PO. Plumb’s p.883: hepatic encephalopathy 22 mg/kg q8h (Cornelius 2000) or 20 mg/kg q8–12h with lactulose (Marks 2004); campylobacteriosis 20 mg/kg PO q12h.

### Cattle

*Neomycin doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Enteric colibacillosis (oral) | 7–12 mg/kg | PO | q12h | — | Withdrawal NOT established — treat as extra-label |

- Enteric colibacillosis (oral): Plumb’s p.883: 7–12 mg/kg PO q12h (Howard 1986); 10–20 mg/kg q12h (Jenkins); label water/milk-replacer medication to supply 11 mg/kg/day. Papich 5e: calves, sheep, goats and pigs 22 mg/kg/day PO. Follow the product-label slaughter withdrawal.

### Horses

*Neomycin doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Enteric infection | 5–15 mg/kg | PO | q24h | — |

- Enteric infection: Plumb’s p.883: 5–15 mg/kg PO once daily (Robinson 1987); adults 4–7.5 g/day and foals 2–3 g/day divided (Brander) — not standardised. Colitis risk in horses.

### Goats

*Neomycin doses for goats*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Enteric colibacillosis (oral) | 11 mg/kg | PO | q12h | ≤5 days | Withdrawal NOT established — treat as extra-label |

- Enteric colibacillosis (oral): Papich 5e: calves, sheep, goats and pigs 22 mg/kg/day PO — shown here as 11 mg/kg q12h. Oral gut-local action (not absorbed from the intact gut). Follow the product label withdrawal. Do NOT use parenterally.

### Sheep

*Neomycin doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Enteric colibacillosis (oral) | 11 mg/kg | PO | q12h | ≤5 days | Withdrawal NOT established — treat as extra-label |

- Enteric colibacillosis (oral): Papich 5e: calves, sheep, goats and pigs 22 mg/kg/day PO — shown here as 11 mg/kg q12h. Plumb’s (Brander 1982): lambs 0.75–1 g/day PO divided 2–4 times daily. Oral gut-local action. Follow the product label withdrawal. Do NOT use parenterally.

### Pigs

*Neomycin doses for pigs*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Colibacillosis / bacterial enteritis (oral) | 11 mg/kg | PO | q12h | ≤5 days | Withdrawal NOT established — treat as extra-label |

- Colibacillosis / bacterial enteritis (oral): Papich 5e: calves, sheep, goats and pigs 22 mg/kg/day PO — shown here as 11 mg/kg q12h. Plumb’s (Brander 1982): young pigs 0.75–1 g/day PO divided 2–4 times daily (doses not standardised). Oral gut-local action (not absorbed from the intact gut). Follow the product label withdrawal. Do NOT use parenterally.

### Buffalo

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

*Neomycin doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Enteric colibacillosis (oral) | 7–12 mg/kg | PO | q12h | — | Withdrawal NOT established — treat as extra-label |

- Enteric colibacillosis (oral): Plumb’s p.883: 7–12 mg/kg PO q12h (Howard 1986); 10–20 mg/kg q12h (Jenkins); label water/milk-replacer medication to supply 11 mg/kg/day. Papich 5e: calves, sheep, goats and pigs 22 mg/kg/day PO. Follow the product-label slaughter withdrawal.

### Birds

*Neomycin doses for birds*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Bacterial enteritis (flock water/feed) | 11 mg/kg | PO | daily in drinking water | — |

- Bacterial enteritis (flock water/feed): Plumb’s p.883 (Neomix label): chickens, turkeys and ducks — medicate feed at 70–140 g/ton or water consumed in 12 h to provide 11 mg/kg/day. Not absorbed — not for systemic infections. Observe the label withdrawal in poultry.

### Rabbits

*Neomycin doses for rabbits*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Contraindicated | Contraindicated in rabbits and hares | — | — | — |

- Contraindicated: Plumb’s p.883: neomycin is contraindicated in rabbits/hares.

### Ferrets

*Neomycin doses for ferrets*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Enteric infection | 10–20 mg/kg | PO | q6–12h | — |

- Enteric infection: Plumb’s p.883 (Williams 2000): 10–20 mg/kg PO two to four times daily.

### Guinea pigs

*Neomycin doses for guinea pigs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Enteric infection | 8 mg/kg | PO | q24h | — |

- Enteric infection: Plumb’s p.883 (Adamcak & Otten 2000): guinea pigs 8 mg/kg PO once daily.

### Chinchillas

*Neomycin doses for chinchillas*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Enteric infection | 15 mg/kg | PO | q24h | — |

- Enteric infection: Plumb’s p.883 (Adamcak & Otten 2000): chinchillas 15 mg/kg PO once daily.

## Contraindications

Intestinal obstruction or mucosal ulceration (allows systemic absorption → toxicity). Pre-existing renal failure or hearing deficit if any systemic exposure is possible. Avoid systemic/parenteral routes entirely. Do not use on large denuded skin areas (absorption).

## Species-specific warnings

> **Caution:** Horses: High risk of fatal antibiotic-associated colitis — use oral neomycin only with great caution in horses.

> **Caution:** Cats: Avoid prolonged oral use; cats are prone to aminoglycoside toxicity if any absorption occurs.

## Adverse effects

- Oral: disruption of gut flora, malabsorption, diarrhoea/superinfection on prolonged use
- Nephrotoxicity and ototoxicity IF absorbed (damaged gut, large topical areas)
- Contact dermatitis / hypersensitivity (topical)
- Neuromuscular blockade with systemic absorption

## Drug interactions

- Oral neomycin reduces absorption of digoxin, vitamin K, and some other oral drugs/nutrients
- Potentiates oral anticoagulants by lowering vitamin-K-producing gut flora
- Additive nephro-/ototoxicity with loop diuretics or other aminoglycosides if any absorption occurs
- Neuromuscular blockers / anaesthetics: potentiated blockade with systemic exposure
- Penicillins: physically incompatible if mixed

## Pregnancy and lactation

Oral/topical use with an intact barrier gives negligible systemic exposure and is low-risk. Avoid any systemic absorption in pregnancy (fetal ototoxicity/nephrotoxicity).

## Monitoring

- GI tolerance — stop if diarrhoea worsens (dysbiosis)
- Renal/auditory signs if gut integrity is compromised
- Limit oral courses to ≤1 week to avoid malabsorption
- Topical sites for contact hypersensitivity

## Toxicity and overdose

Toxicity is the concern only when the drug is absorbed — through ulcerated/obstructed gut or large denuded skin. Then expect aminoglycoside nephrotoxicity (tubular necrosis) and irreversible ototoxicity. Prolonged oral use causes malabsorption and antibiotic-associated diarrhoea/superinfection.

Management: Stop the drug. If systemically absorbed, manage as aminoglycoside toxicity: IV fluid diuresis, monitor renal values and hearing; supportive care for neuromuscular blockade (calcium, ventilation). Discontinue and restore normal flora for oral overdose / dysbiosis.

## Clinical pearls

- Think of oral neomycin as a "luminal" antibiotic — its value is precisely that it is NOT absorbed
- Classic adjunct (with lactulose) for hepatic encephalopathy, but reserve for refractory cases due to dysbiosis risk
- Never give neomycin parenterally — it is the most toxic aminoglycoside systemically
- In India, Nebasulf (neomycin + bacitracin + sulfacetamide) powder is a staple for superficial wounds
- Avoid in horses with any GI inflammation — colitis can follow flora disruption

## Mechanism of action

Aminoglycoside that binds the 30S ribosomal subunit, causing mRNA misreading and blockade of protein synthesis (bactericidal). Given orally it stays in the gut lumen, suppressing enteric Gram-negative bacteria and reducing intestinal ammonia/urease-producing flora — the basis of its use in hepatic encephalopathy.

## Formulations and products

- Oral solution / bolus (gut infection)
- Topical powder/cream (with bacitracin ± polymyxin)
- Intramammary / intrauterine combination
- Nebasulf powder/cream (Pfizer / various (India)) — Neomycin + Bacitracin + Sulfacetamide, Topical powder / cream
- Neomycin oral bolus (Various) — Neomycin sulphate, Oral bolus / solution
- Moxomast-200 (Micro Animal Health Care (Micro Labs group), Bengaluru) — Neomycin 100 mg + Cephalexin 100 mg + Prednisolone 10 mg per 5 g, Intramammary infusion syringe
- Neosporin — Neomycin + Polymyxin B + Bacitracin, Topical / eye ointment (human-label)

## Storage

Oral and topical products: 15–30 °C, dry. Combination creams/powders per label. Protect from moisture.

## 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

- [Marbofloxacin](https://vetmasterji.com/drugs/marbofloxacin)
- [Meropenem](https://vetmasterji.com/drugs/meropenem)
- [Minocycline](https://vetmasterji.com/drugs/minocycline)
- [Mupirocin](https://vetmasterji.com/drugs/mupirocin)
- [Nitrofurantoin](https://vetmasterji.com/drugs/nitrofurantoin)
- [Norfloxacin](https://vetmasterji.com/drugs/norfloxacin)
- [Orbifloxacin](https://vetmasterji.com/drugs/orbifloxacin)
- [Ornidazole](https://vetmasterji.com/drugs/ornidazole)

## Frequently asked questions

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

Reference doses for Neomycin in dogs: 10–20 mg/kg PO q6–12h for ≤5–7 days (Enteric infection (local)); 10–20 mg/kg PO q8–12h (Hepatic encephalopathy). Confirm against the label and the patient before use.

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

Reference doses for Neomycin in cats: 10–22 mg/kg PO q8–12h (Enteric infection / HE). Confirm against the label and the patient before use.

### What is the dose of Neomycin for cattle?

Reference doses for Neomycin in cattle: 7–12 mg/kg PO q12h (Enteric colibacillosis (oral)). Confirm against the label and the patient before use.

### What is the withdrawal period for Neomycin?

Cattle, PO (Enteric colibacillosis (oral)): Withdrawal NOT established — treat as extra-label; Goats, PO (Enteric colibacillosis (oral)): Withdrawal NOT established — treat as extra-label; Sheep, PO (Enteric colibacillosis (oral)): Withdrawal NOT established — treat as extra-label; Pigs, PO (Colibacillosis / bacterial enteritis (oral)): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Neomycin not be used?

Intestinal obstruction or mucosal ulceration (allows systemic absorption → toxicity). Pre-existing renal failure or hearing deficit if any systemic exposure is possible. Avoid systemic/parenteral routes entirely. Do not use on large denuded skin areas (absorption).

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

Oral: disruption of gut flora, malabsorption, diarrhoea/superinfection on prolonged use; Nephrotoxicity and ototoxicity IF absorbed (damaged gut, large topical areas); Contact dermatitis / hypersensitivity (topical); Neuromuscular blockade with systemic absorption.

## 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.