Neomycin: veterinary dose and monograph

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

• 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

• 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

• 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

• 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

• 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

• 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

• 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.

• 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

• 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

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

Ferrets

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

Guinea pigs

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

Chinchillas

• 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

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

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

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
• Meropenem
• Minocycline
• Mupirocin
• Nitrofurantoin
• Norfloxacin
• Orbifloxacin
• Ornidazole

Frequently asked questions