Amoxicillin for Horses

Equine · Equus caballus · typical adult weight 350.00–700.00 kg

Amoxicillin is dosed at 20–30 mg/kg PO q6-8h in horses, per Plumb's Veterinary Drug Handbook, 9th Ed. Amoxicillin is used in horses for Bacterial infection. Routes documented in horses: PO. A typical adult horse weighs 350.00–700.00 kg. ExoticRx lists 1 cited dose rule for Amoxicillin in horses, drawn from published veterinary references. Verify against current literature before clinical use.

US trade names: Amoxi-Tabs, Amoxil

Contraindicated in Rabbit, Guinea Pig, Chinchilla, Hamster, Degu

Rabbit: Oral beta-lactams cause fatal dysbiosis in rabbitsOral amoxicillin (and other oral beta-lactams) selectively destroy gram-positive hindgut flora in rabbits, allowing Clostridium spiroforme overgrowth and fatal enterotoxemia. Never administer oral beta-lactams to rabbits. Parenteral administration carries a lower risk than the oral route, but is not established as safe in rabbits.
Guinea Pig: Oral beta-lactams cause fatal dysbiosis in guinea pigsOral amoxicillin reliably causes Clostridium difficile-mediated fatal enterotoxemia in guinea pigs. Same mechanism as in rabbits. Parenteral administration carries a lower risk than the oral route; parenteral ceftiofur specifically has been given to guinea pigs and chinchillas without adverse effect.
Chinchilla: Oral beta-lactams cause fatal dysbiosis in chinchillasChinchillas are hindgut fermenters with the same flora dependence as rabbits and guinea pigs. Oral penicillins and oral cephalosporins trigger Clostridium overgrowth and fatal enterotoxemia. Never give oral beta-lactams; parenteral routes and trimethoprim-sulfa, fluoroquinolones, or chloramphenicol are the safer choices.
Hamster: Oral beta-lactams cause fatal enterocolitis in hamstersHamsters are exquisitely susceptible to antibiotic-associated Clostridium difficile enterocolitis — the hamster is the classic laboratory model for it. Oral penicillins and cephalosporins are reliably fatal. Never administer oral beta-lactams.
Degu: Oral beta-lactams risk fatal dysbiosis in degusDegus are caviomorph hindgut fermenters closely related to chinchillas and guinea pigs. Degu-specific data is limited, so this warning is extrapolated from those related hystricomorphs — but the shared physiology makes oral beta-lactam enterotoxemia the expected outcome. Treat as contraindicated; use the safer alternatives.

Dose ranges

Route	Dose	Frequency	Duration	Indication	Evidence	Source
PO	20–30 mg/kg	q6-8h	5-7 days	Bacterial infection	Weak	Plumb's Veterinary Drug Handbook, 9th Ed

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Mechanism of action

Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs).

Side effects & warnings

CONTRAINDICATED in rabbits, guinea pigs, and hamsters (fatal dysbiosis). May cause GI upset. Cross-reactivity with other beta-lactams.

Species-specific contraindications and adverse-reaction reports for horses may differ from canine / feline reference data — consult the primary citations listed with each rule.

Frequently asked questions

What is the dose of Amoxicillin for Horses?

Amoxicillin dose range in horses, with cited source references: PO 20–30 mg/kg q6-8h. Reference ranges from cited sources — verify against current literature before clinical use.

How is Amoxicillin administered in Horses?

Documented routes for Amoxicillin in horses: PO.

How long is Amoxicillin given in Horses?

Cited course lengths for Amoxicillin in horses include: 5-7 days. Duration depends on the indication — match it to the specific dose rule in the table above.

What conditions does Amoxicillin treat in Horses?

Amoxicillin is indicated in horses for: Bacterial infection.

What are the side effects of Amoxicillin in Horses?

These are general warnings for Amoxicillin across species; consult the horse dosing table above for species-specific guidance. CONTRAINDICATED in rabbits, guinea pigs, and hamsters (fatal dysbiosis). May cause GI upset. Cross-reactivity with other beta-lactams.

Other Antibiotic drugs with horse dosing

Amikacin Ampicillin Azithromycin Cefquinome (Livestock)Ceftiofur Chloramphenicol Doxycycline Enrofloxacin Erythromycin Gentamicin Marbofloxacin (Livestock)Metronidazole

Amoxicillin dosing in other species

African Grey Parrots Bearded Dragons Cats Cattle Dogs Ferrets Pet Rats Sugar Gliders

See all species for Amoxicillin See all drugs for Horses

Why a species-specific page? Amoxicillin pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in horses — the rules above are the citations specific to this species, not generic recommendations.

Sourced from published veterinary references; awaiting credentialed clinical reviewer. See our editorial process. Reference only — not veterinary advice.