Carbenicillin for Cats

Cat · Felis catus · typical adult weight 2.50–7.00 kg

Carbenicillin is dosed at 10 mg/kg PO q8h in cats, per Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed (2016), Carbenicillin, p.135, 'Small Animal Dosage — Dogs and Cats' — LOCATOR CONVENTION 2026-08-07: the bare 'p.135' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.107; verified by finding the drug named there. If you are holding the book, turn to p.107. — SOURCE EDITION: Saunders Handbook of Veterinary Drugs — ISBN 9780323244855, https://openlibrary.org/isbn/9780323244855. Carbenicillin is used in cats for Urinary tract infections. Routes documented in cats: PO. A typical adult cat weighs 2.50–7.00 kg. ExoticRx lists 1 cited dose rule for Carbenicillin in cats, drawn from published veterinary references. Verify against current literature before clinical use.

US trade names: Geocillin, Pyopen

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	10 mg/kg	q8h	7-14 days	Urinary tract infections	Weak	Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed (2016), Carbenicillin, p.135, 'Small Animal Dosage — Dogs and Cats' — LOCATOR CONVENTION 2026-08-07: the bare 'p.135' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.107; verified by finding the drug named there. If you are holding the book, turn to p.107. — SOURCE EDITION: Saunders Handbook of Veterinary Drugs — ISBN 9780323244855, https://openlibrary.org/isbn/9780323244855

What each reference text prints

Every held source for this drug and species, as printed. Where they differ, both are shown — the choice is yours, not ours.

Printed doses in mg/kg for this drug and species, by source
Dose (mg/kg)	Route	Source	As printed
40–50	IV	Papich Saunders Handbook of Veterinary Drugs, 4th edp.135	• Carbenicillin: 40-50 mg/kg and up to 100 mg/kg q6-8h IV, IM, or SQ.
100	IV	Papich Saunders Handbook of Veterinary Drugs, 4th edp.135	• Carbenicillin: 40-50 mg/kg and up to 100 mg/kg q6-8h IV, IM, or SQ.
10	PO	Papich Saunders Handbook of Veterinary Drugs, 4th edp.135	• Carbenicillin indanyl sodium: 10 mg/kg q8h PO.

Figures are transcribed from the cited page or table of each held edition and are shown for reference only. They are not dose recommendations, they do not feed the calculator, and none has been reviewed by a veterinarian.

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Mechanism of action

Inhibits bacterial cell wall synthesis by binding PBPs. Extended-spectrum penicillin with Pseudomonas activity.

Side effects & warnings

High sodium content in parenteral form. May cause platelet dysfunction at high doses. GI upset with oral use.

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

Frequently asked questions

What is the dose of Carbenicillin for Cats?

Carbenicillin dose range in cats, with cited source references: PO 10 mg/kg q8h. Reference ranges from cited sources — verify against current literature before clinical use.

How is Carbenicillin administered in Cats?

Documented routes for Carbenicillin in cats: PO.

How long is Carbenicillin given in Cats?

Cited course lengths for Carbenicillin in cats include: 7-14 days. Duration depends on the indication — match it to the specific dose rule in the table above.

What conditions does Carbenicillin treat in Cats?

Carbenicillin is indicated in cats for: Urinary tract infections.

What are the side effects of Carbenicillin in Cats?

These are general warnings for Carbenicillin across species; consult the cat dosing table above for species-specific guidance. High sodium content in parenteral form. May cause platelet dysfunction at high doses. GI upset with oral use.

Other Antibiotic drugs with cat dosing

Amikacin Amoxicillin Amoxicillin Injectable Amoxicillin-Clavulanate Ampicillin Azithromycin Bacitracin Cefaclor Cefadroxil Cefazolin Cefdinir Cefepime

Carbenicillin dosing in other species

Dogs Great Horned Owls Harris Hawks Peregrine Falcons Red-tailed Hawks Russian Tortoises

See all species for Carbenicillin See all drugs for Cats

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