Ampicillin for Chickens

Livestock · Gallus gallus domesticus · typical adult weight 0.50–5.00 kg

Ampicillin is dosed at 55–110 mg/kg IM q8-12 hr in chickens, per Greenacre, C.B., Luna, G.L., and Morishita, T.M. (2018). Backyard poultry and waterfowl. In: Exotic Animal Formulary, 5e (ed. J.W. Carpenter), 377-432. St. Louis, Missouri: Elsevier. — Mined from Greenacre & Morishita, Backyard Poultry Medicine and Surgery, 2nd Ed, p.588 (2026-08-01, PENDING REVIEW). Ampicillin is used in chickens for Clostridiosis. Routes documented in chickens: IM. A typical adult chicken weighs 0.50–5.00 kg. ExoticRx lists 1 cited dose rule for Ampicillin in chickens, drawn from published veterinary references. Verify against current literature before clinical use.

US trade names: Polyflex

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	Indication	Evidence	Source
IM	55–110 mg/kg	q8-12 hr	Clostridiosis	Moderate	Greenacre, C.B., Luna, G.L., and Morishita, T.M. (2018). Backyard poultry and waterfowl. In: Exotic Animal Formulary, 5e (ed. J.W. Carpenter), 377-432. St. Louis, Missouri: Elsevier. — Mined from Greenacre & Morishita, Backyard Poultry Medicine and Surgery, 2nd Ed, p.588 (2026-08-01, PENDING REVIEW)

Report an error in this entry

Need the exact dose for your patient?

These ranges are per kg. Enter your chicken's weight to get the precise dose and draw-up volume — unit and concentration math done for you.

Calculate for this chicken →

Mechanism of action

Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins. Broader spectrum than penicillin G with gram-negative coverage.

Side effects & warnings

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

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

Frequently asked questions

What is the dose of Ampicillin for Chickens?

Ampicillin dose range in chickens, with cited source references: IM 55–110 mg/kg q8-12 hr. Reference ranges from cited sources — verify against current literature before clinical use.

How is Ampicillin administered in Chickens?

Documented routes for Ampicillin in chickens: IM.

What conditions does Ampicillin treat in Chickens?

Ampicillin is indicated in chickens for: Clostridiosis.

What are the side effects of Ampicillin in Chickens?

These are general warnings for Ampicillin across species; consult the chicken 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. IM injection may be painful.

Other Antibiotic drugs with chicken dosing

Amikacin Amoxicillin Amoxicillin-Clavulanate Avilamycin Bacitracin (Livestock Feed)Bambermycin Chlortetracycline Doxycycline Enramycin Enrofloxacin Erythromycin Florfenicol

Ampicillin dosing in other species

Cattle Swine Turkeys African Grey Parrots Amazon Parrots Ball Pythons Bearded Dragons Blue-tongue Skinks

See all species for Ampicillin See all drugs for Chickens

Why a species-specific page? Ampicillin pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in chickens — 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.