What is Cefaclor used for?

Cefaclor is indicated for: Urinary tract infection.

Which species have cited Cefaclor dosing data?

Cefaclor dosing in the ExoticRx formulary covers 2 species: Cat (Domestic), Dog (Domestic).

Is Cefaclor a controlled substance?

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

What are the side effects of Cefaclor?

Reported side effects, adverse reactions, and contraindications for Cefaclor: GI upset possible. Cross-reactivity with penicillin allergy. Adjust dose in renal impairment.

Cefaclor

US brand names:Ceclor, Raniclor

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.

Sourced from published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.

Cefaclor is dosed at 10–15 mg/kg PO q8h in cats, per Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.225 (2026-08-01).. Verify against current literature before clinical use.

Drug Class

Antibiotic

Routes

Indications

Urinary tract infection

Mechanism of Action

Binds to penicillin-binding proteins (PBPs) and inhibits bacterial cell wall synthesis. Bactericidal.

Side effects & warnings

GI upset possible. Cross-reactivity with penicillin allergy. Adjust dose in renal impairment.

Species with Cefaclor dosing data (2 dose rules)

Cat (Domestic)Dog (Domestic)

Species references:All Cat (Domestic) drugs All Dog (Domestic) drugs

Evidence levels across 2 dose rules

Weak×2

Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.

Backed by a published source

· Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.225 (2026-08-01).

Sample dosing (2 of 2 cited rules)

A dog/cat sample is shown here. Cited dosing for all 2 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)	PO	10–15 mg/kg	q8h	Weak	Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.225 (2026-08-01).
Dog (Domestic)	PO	10–20 mg/kg	q8h	Weak	Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.225 (2026-08-01).

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