Cephalexin for Pet Rats

Pocket Pet · Rattus norvegicus var. domestica · typical adult weight 0.25–0.70 kg

Cephalexin is dosed at 20 mg/kg PO q8h in pet rats, per Visser C, Wijnbergen A, Bleich A. Maeuse und ratten. In: Fehr M, Sassenburg L, Zwart P, eds. Krankheiten der Heimtiere, Schluetersche Verlagsgesellschaft, Hannover, Germany; 2015. — Mined from Carpenter's Exotic Animal Formulary, 6th Ed, p.771 (2026-08-01, PENDING REVIEW). Cephalexin is used in pet rats for Bacterial infection (first-generation cephalosporin). Routes documented in pet rats: PO, SC, IM. A typical adult pet rat weighs 0.25–0.70 kg. ExoticRx lists 2 cited dose rules for Cephalexin in pet rats, drawn from published veterinary references. Verify against current literature before clinical use.

US trade names: Keflex

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
PO	20 mg/kg	q8h	Bacterial infection (first-generation cephalosporin)	Moderate	Visser C, Wijnbergen A, Bleich A. Maeuse und ratten. In: Fehr M, Sassenburg L, Zwart P, eds. Krankheiten der Heimtiere, Schluetersche Verlagsgesellschaft, Hannover, Germany; 2015. — Mined from Carpenter's Exotic Animal Formulary, 6th Ed, p.771 (2026-08-01, PENDING REVIEW)
SC, IM	15 mg/kg	q12h	Bacterial infection (first-generation cephalosporin)	Weak	Flecknell PA. Analgesia and post-operative care. Laboratory Animal Anaesthesia; 2016:141-192. — Mined from Carpenter's Exotic Animal Formulary, 6th Ed, p.771 (2026-08-01, PENDING REVIEW)

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Mechanism of action

Inhibits bacterial cell wall synthesis by binding to PBPs. First-generation cephalosporin with good gram-positive coverage.

Side effects & warnings

May cause GI upset. Use with caution in penicillin-allergic animals (cross-reactivity). Not effective against Pseudomonas.

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

Frequently asked questions

What is the dose of Cephalexin for Pet Rats?

Cephalexin dose ranges in pet rats, with cited source references: PO 20 mg/kg q8h; SC, IM 15 mg/kg q12h. Reference ranges from cited sources — verify against current literature before clinical use.

How is Cephalexin administered in Pet Rats?

Documented routes for Cephalexin in pet rats: PO, SC, IM.

What conditions does Cephalexin treat in Pet Rats?

Cephalexin is indicated in pet rats for: Bacterial infection (first-generation cephalosporin).

What are the side effects of Cephalexin in Pet Rats?

These are general warnings for Cephalexin across species; consult the pet rat dosing table above for species-specific guidance. May cause GI upset. Use with caution in penicillin-allergic animals (cross-reactivity). Not effective against Pseudomonas.

Other Antibiotic drugs with pet rat dosing

Amikacin Amoxicillin Amoxicillin-Clavulanate Ampicillin Azithromycin Chloramphenicol Ciprofloxacin Clindamycin Doxycycline Enrofloxacin Erythromycin Gentamicin

Cephalexin dosing in other species

African Pygmy Hedgehogs Dwarf Hamsters Ferrets Gerbils Mice Sugar Gliders Syrian Hamsters African Grey Parrots

See all species for Cephalexin See all drugs for Pet Rats

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