Neomycin

Neomycin is an aminoglycoside antibacterial used mainly in topical preparations and for local intestinal effects after oral administration. Its poor gastrointestinal absorption supports treatment of selected enteric infections and reduction of intestinal ammonia-producing bacteria. Skin, ophthalmic and otic products often combine it with other active ingredients to broaden local treatment coverage.

Group

Aminoglycoside antibacterial

Mechanism of Action

Neomycin binds the bacterial 30S ribosomal subunit, causing translation errors and disruption of protein synthesis, with additional membrane effects contributing to bacterial killing. Activity primarily targets susceptible aerobic organisms. Oral drug remaining in the lumen suppresses susceptible intestinal bacteria; reduction of ammonia-producing populations provides the rationale for hepatic encephalopathy use. Topical formulations act at the treated surface.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Enteric bacterial infection	10–20 mg/kg	PO	Every 6–12 h	Up to 14 days
Hepatic encephalopathy	20 mg/kg	PO	Every 8 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Portosystemic shunt adjunct	10–20 mg/kg	PO	Every 8–12 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Hepatic encephalopathy	20 mg/kg	PO	Every 12 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Hepatic encephalopathy	10–20 mg/kg	PO	Every 6 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Campylobacter enteritis	20 mg/kg	PO	Every 12 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Hepatic encephalopathy	15 mg/kg	RECTAL	Every 6 h	After a cleansing enema; may be combined with lactulose.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Enteric bacterial infection	10–20 mg/kg	PO	Every 6–12 h	Up to 14 days
Hepatic encephalopathy	22 mg/kg	PO	Every 8 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Hepatic encephalopathy	20 mg/kg	PO	Every 8–12 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Hepatic encephalopathy	20 mg/kg	PO	Every 12 h	Do not use in: Intestinal bleeding or ulceration, Renal failure
Campylobacter enteritis	20 mg/kg	PO	Every 12 h

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Enteric bacterial infection	22 mg/kg	PO	Every 24 h	Up to 14 days; Cattle regimen is for calves; daily oral amount.
Susceptible enteric infection	7–12 mg/kg	PO	Every 12 h
Enteric infection drinking-water regimen	11 mg/kg	PO		Mix the calculated amount into the drinking water consumed over 12 hours; water consumption determines delivery, not an IV or oral bolus schedule.

Sheep

Use / stage	Dose	Route	Schedule	Instructions
Enteric bacterial infection	22 mg/kg	PO	Every 24 h	Up to 14 days; Cattle regimen is for calves; daily oral amount.
Enteric infection drinking-water regimen	11 mg/kg	PO		Mix the calculated amount into the drinking water consumed over 12 hours; water consumption determines delivery, not an IV or oral bolus schedule.

Goat

Use / stage	Dose	Route	Schedule	Instructions
Enteric bacterial infection	22 mg/kg	PO	Every 24 h	Up to 14 days; Cattle regimen is for calves; daily oral amount.
Enteric infection drinking-water regimen	11 mg/kg	PO		Mix the calculated amount into the drinking water consumed over 12 hours; water consumption determines delivery, not an IV or oral bolus schedule.

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Enteric bacterial infection	22 mg/kg	PO	Every 24 h	Up to 14 days; Cattle regimen is for calves; daily oral amount.
Susceptible enteric infection	7–12 mg/kg	PO	Every 12 h

Ferrets

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	10–20 mg/kg	PO	Every 6–12 h

Chinchillas

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	15 mg/kg	PO	Every 24 h

Gerbils

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	100 mg/kg	PO	Every 24 h

Guinea pigs

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	8 mg/kg	PO	Every 24 h

Hamsters

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	100 mg/kg	PO	Every 24 h

Mice

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	50 mg/kg	PO	Every 24 h

Rats

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	50 mg/kg	PO	Every 24 h

Horses

Use / stage	Dose	Route	Schedule	Instructions
Susceptible enteric infection	5–15 mg/kg	PO	Every 24 h

Chickens

Use / stage	Dose	Route	Schedule	Instructions
Enteric infection drinking-water regimen	11 mg/kg	PO		Mix the calculated amount into the drinking water consumed over 12 hours; water consumption determines delivery, not an IV or oral bolus schedule.

Turkeys

Use / stage	Dose	Route	Schedule	Instructions
Enteric infection drinking-water regimen	11 mg/kg	PO		Mix the calculated amount into the drinking water consumed over 12 hours; water consumption determines delivery, not an IV or oral bolus schedule.

Ducks

Use / stage	Dose	Route	Schedule	Instructions
Enteric infection drinking-water regimen	11 mg/kg	PO		Mix the calculated amount into the drinking water consumed over 12 hours; water consumption determines delivery, not an IV or oral bolus schedule.

Snakes

Use / stage	Dose	Route	Schedule	Instructions
Bacterial gastritis adjunct	15 mg/kg	PO		Oral neomycin is part of a gentamicin 2.5 mg/kg IM every 72 hours plus oral live-lactobacillus protocol; neomycin repeat interval unspecified.

Indications

Local treatment of susceptible superficial skin, ocular or otic bacterial infections with a corresponding formulation.
Oral treatment of selected susceptible enteric bacterial infections, including colibacillosis in livestock with an indicated product.
Reduction of intestinal ammonia-producing bacteria in selected patients with hepatic encephalopathy or portosystemic shunting.
Selected preoperative reduction of intestinal bacterial burden within a supported bowel-surgery protocol.

Contraindications

Renal disease and damaged intestinal mucosa increase risk of systemic toxicity.
Do not inject oral products or continue oral treatment beyond 14 days.

Interactions

Mixing with other medicines may cause binding or inactivation.
Oral neomycin can alter absorption of other drugs; systemic nephrotoxic or ototoxic agents can compound toxicity.

Adverse effects

Diarrhea and altered intestinal flora; absorbed drug can injure kidneys.

Toxicity

Systemically absorbed neomycin can cause severe nephrotoxicity and ototoxicity. Damaged intestinal mucosa, renal disease and injectable exposure increase risk.

Preparations

Preparation	Form	Strength	Route
Neomycin oral liquid (35 mg base/mL) Concentration expressed as neomycin base.	Oral Liquid	35 mg / mL	PO
Neomycin oral liquid (140 mg base/mL) Concentration expressed as neomycin base.	Oral Liquid	140 mg / mL	PO

Monitoring and Administration

Monitor stool, hydration and renal indices when absorption or prolonged exposure is a concern. Benefit for nonspecific diarrhea is uncertain.

Prepare drinking-water or milk solutions freshly each day; avoid other liquid supplements.

Oral neomycin is contraindicated in rabbits and hares. Intestinal inflammation/bleeding increases absorption and renal/ear toxicity. Hepatic encephalopathy treatment also addresses lactulose, nutrition, electrolytes and GI bleeding; oral lactulose does not replace monitoring.

Historical parenteral systemic regimen is 3.5 mg/kg IV, IM or SC every 8 hours in dogs/cats, but is described as very nephrotoxic; no compatible sterile preparation or parent base/sulfate dose basis is established here. It is not assigned to oral products.

Older divided oral daily totals: adult cattle/horses 4-7.5 g/day, calves/foals 2-3 g/day, young pigs/lambs 0.75-1 g/day, in 2-4 divided doses. These general guides lack one defined per-administration interval. Equine intrauterine neomycin 3-4 g or multi-antibiotic mixtures are local procedures with poorly standardized diluents, volumes and intervals.