What is Ampicillin used for?

Ampicillin is indicated for: bacteremia, Bacterial infection, erysipelas, listeriosis, Respiratory, Respiratory infections, soft tissue infections, Surgical prophylaxis, Susceptible bacterial infections.

What routes can Ampicillin be administered by?

Available routes: PO, IV, IM, SC.

Which species have cited Ampicillin dosing data?

Ampicillin dosing in the ExoticRx formulary covers 7 species: African Grey Parrot, Cat (Domestic), Cattle (Beef/Dairy), Dog (Domestic), Horse (Equine), Russian Tortoise, Swine (Pig).

Is Ampicillin a controlled substance?

Ampicillin is not federally scheduled in the US. Controlled-drug status differs by country — verify your local rules.

What are the warnings or contraindications for Ampicillin?

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

What are the side effects of Ampicillin?

Reported side effects, adverse reactions, and contraindications for Ampicillin: CONTRAINDICATED in rabbits, guinea pigs, and hamsters (fatal dysbiosis). May cause GI upset. Cross-reactivity with other beta-lactams. IM injection may be painful.

How does Ampicillin work?

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

Ampicillin

US brand names:Polyflex

Calculate dosage

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.

Ampicillin is dosed at 50 mg/kg IM q 12 h in russian tortoises, per Spörle H, Gobel T, Schildger B. Blood levels of some anti-infectives in the spur-thighed tortoise (Testudo hermanni). Proc 4th Intl Colloq Path Med Rept Amph; 1991:120-128. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.212 (2026-08-01).. Verify against current literature before clinical use.

Backed by 6 published sources

· Carpenter's Exotic Animal Formulary, 6th Ed
· MacDonald K. Infective endocarditis in dogs: diagnosis and therapy. Vet Clin North Am Small Anim Pract. 2010;40:665-684. doi:10.1016/j.cvsm.2010.03.010 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.107 (2026-08-01).
· Plumb's Veterinary Drug Handbook
· Plumb's Veterinary Drug Handbook, 9th Ed
· Spörle H, Gobel T, Schildger B. Blood levels of some anti-infectives in the spur-thighed tortoise (Testudo hermanni). Proc 4th Intl Colloq Path Med Rept Amph; 1991:120-128. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.212 (2026-08-01).
· Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.107 (2026-08-01).

Sample dosing (2 of 10 cited rules)

A dog/cat sample is shown here. Cited dosing for all 7 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.

Species	Route	Dose	Frequency	Evidence	Source
Cat (Domestic)	IV	22–40 mg/kg	q6-8h	Strong	Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.107 (2026-08-01).
Dog (Domestic)	PO	10–20 mg/kg	q6-8h	Strong	Plumb's Veterinary Drug Handbook, 9th Ed

Ampicillin

Drug Class

Routes

Indications

Mechanism of Action

Side effects & warnings

Species with Ampicillin dosing data (10 dose rules)

Evidence levels across 10 dose rules

Backed by 6 published sources

Sample dosing (2 of 10 cited rules)

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Ampicillin

Drug Class

Routes

Indications

Mechanism of Action

Side effects & warnings

Species with Ampicillin dosing data (10 dose rules)

Evidence levels across 10 dose rules

Backed by 6 published sources

Sample dosing (2 of 10 cited rules)

Upgrade for Full Details

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