Cephalexin: veterinary dose and monograph

At a glance

Drug class

Antibiotic

Also known as

Keflex

Species with doses

Dogs, Cats, Horses, Pigs, Birds, Rabbits, Ferrets, Guinea pigs, Hedgehogs, Sugar gliders and Primates

General dose range

22–35 mg/kg PO q8–12h — check the species tables for the indication

Routes

PO, IM

Last reviewed

1 October 2026

Indications

• Staphylococcal pyoderma (superficial / deep / recurrent)
• Skin and soft tissue infections
• Bacterial cystitis / pyelonephritis (UTI)
• Pyometra / metritis (adjunct)
• Orthopaedic / wound infections
• Otitis externa (adjunct)

Cephalexin dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Superficial / deep pyoderma: Plumb’s p.241: 22–33 mg/kg PO two to three times daily (Beale & Murphy); recurrent pyoderma 22 mg/kg q12h, q8h for deep pyoderma (Hillier); 22–35 mg/kg q12h or 22 mg/kg q8h (Greene). Papich 5e: 22–25 mg/kg q12h PO. Continue 5–7 days (deep pyoderma longer) past clinical resolution.
• Soft tissue infection: Plumb’s p.241 (Greene & Watson 1998): soft tissue infections 30–50 mg/kg PO q12h; respiratory 20–40 mg/kg q8h; treat 5–7 days beyond resolution.
• UTI / urethrocystitis: Plumb’s p.241 (Brovida 2003): 30–40 mg/kg PO q8h — acute urethrocystitis 7–10 days, chronic up to 4 weeks, pyelonephritis 4–8 weeks. Papich 5e: 22–25 mg/kg q12h PO.
• Orthopaedic infection: Plumb’s p.241 (Greene & Watson 1998): orthopaedic infections 22–30 mg/kg PO q6–8h for 28 days.
• Systemic infection: Plumb’s p.241 (Greene & Watson 1998): systemic infections 25–60 mg/kg PO q8h; treat 5–7 days beyond clinical resolution or negative culture. Papich 5e (pyoderma, soft tissue, UTI): 22–25 mg/kg q12h PO.

Cats

• Susceptible bacterial infection: Plumb’s p.241: 22 mg/kg PO q8h with food if GI upset (Vaden & Papich); Gram-positive 22 mg/kg q12h, Gram-negative 30 mg/kg q8h (Aucoin); 20–40 mg/kg q8h (Lappin). Papich 5e: 22–25 mg/kg q12h PO.
• Soft tissue / systemic: Plumb’s p.241 (Greene & Watson 1998): soft tissue 30–50 mg/kg PO q12h; systemic infections 35 mg/kg PO q6–8h.

Horses

• Susceptible infection: Papich 5e and Plumb’s p.242 (Davis 2005): 30 mg/kg PO q8h for Gram-positive bacteria with MIC ≤0.5 µg/mL; 22–33 mg/kg PO q6h (Brumbaugh).

Pigs

• Miniature/pet pig — susceptible infection: Carpenter Exotic Animal Formulary 6th ed, Table 12-1 (p.659): miniature pigs 10–30 mg/kg PO q6–12h. Note: extra-label cephalosporin use in food-producing animals is prohibited in the US — applies to pet mini pigs only where legally permissible.

Birds

• Susceptible infection (suspension): Plumb's p.242: 35–50 mg/kg PO 4×/day (suspension); ratites 15–22 mg/kg PO q8h.

Rabbits

• Susceptible infection: Plumb's p.241 (Ivey & Morrisey 2000): rabbits 11–22 mg/kg PO q8h.

Ferrets

• Susceptible infection: Plumb's p.242 (Williams 2000): 15–25 mg/kg PO 2–3 times daily.

Guinea pigs

• Susceptible infection: Plumb's p.241 (Adamcak & Otten 2000): guinea pigs 50 mg/kg IM q24h.

Hedgehogs

• Susceptible infection: Carpenter Exotic Animal Formulary 6th ed, Table 8-1 (p.512): hedgehogs 25 mg/kg PO q8h — may make stools loose.

Sugar gliders

• Susceptible infection: Carpenter Exotic Animal Formulary 6th ed, Table 7-1 (p.497): sugar gliders 30 mg/kg PO/SC divided q12–24h.

Primates

• Susceptible infection (monkeys): Carpenter Exotic Animal Formulary 6th ed, Table 13-1 (p.681): monkeys 30 mg/kg PO q12h; brown lemurs 20 mg/kg PO q12h.

Contraindications

Hypersensitivity to cephalosporins (possible cross-reactivity with penicillins). Not for septic / shocky animals via PO route — use parenteral. Caution in renal insufficiency or with other nephrotoxic drugs. Generally avoid in neonates.

Species-specific warnings

Dogs: First-line for superficial / deep pyoderma. Minimum 21 days; deep pyoderma may need 6–8 weeks. Cross-reactivity with penicillin allergy ~10%.

Cats: Useful for UTI, abscess, soft-tissue infection. Same dose as dogs (22 mg/kg PO q12h). Compliance often a challenge — cefovecin injectable is an alternative.

Rabbits: NEVER orally in rabbits — fatal Clostridium overgrowth.

Small mammals: NEVER orally in guinea pigs, chinchillas, hamsters — fatal dysbiosis.

Cattle: Not commonly used orally in cattle. Extra-label parenteral use for soft tissue — verify withdrawal with FARAD.

Adverse effects

• GI: vomiting, diarrhoea, inappetence
• Salivation, tachypnoea, excitability (dogs)
• Emesis and fever (cats)
• Hypersensitivity reactions
• Rare: toxic epidermal necrolysis (cats)
• Antibiotic-associated diarrhoea / dysbiosis

Drug interactions

• Aminoglycosides (gentamicin): additive nephrotoxicity at high doses; synergistic against Gram-negatives
• Probenecid: prolongs cephalexin half-life via blocked tubular secretion
• Furosemide / loop diuretics: additive nephrotoxicity risk in dehydrated patients
• Penicillins: cross-reactivity for hypersensitivity (~10% co-allergy)
• Anticoagulants (warfarin): may potentiate effect
• Antacids / cholestyramine: reduced oral absorption

Pregnancy and lactation

Considered safe in pregnant dogs, cats, and cattle at therapeutic doses. Crosses placenta and enters milk in low amounts. Widely used for pre-partum pyoderma, post-partum metritis. FDA Category B (human).

Monitoring

• Hypersensitivity signs (especially first dose) — particularly in penicillin-allergic patients
• Renal function (BUN, creatinine) at baseline and on prolonged courses
• GI tolerance — give with food if vomiting occurs
• CBC if treatment exceeds 2 weeks — rare neutropenia / thrombocytopenia
• Clinical response — pyoderma typically improves within 7–10 days; failure suggests resistance or wrong diagnosis

Toxicity and overdose

Very wide therapeutic index. Acute toxicity rare even at 10× label dose. Chronic: GI upset (vomiting, anorexia, diarrhoea) most common; rarely pseudomembranous colitis, neutropenia, hepatic enzyme elevation. Hypersensitivity (urticaria, anaphylaxis) — cross-reactivity with penicillins in ~10% of allergic patients. Rabbits / guinea pigs: AVOID oral route — fatal Clostridium overgrowth.

Management: No specific antidote. Supportive: IV fluids, anti-emetic if vomiting. Anaphylaxis: epinephrine 0.01 mg/kg IM, diphenhydramine 2–4 mg/kg IM, corticosteroid, oxygen. Activated charcoal not typically useful — rapid absorption.

Clinical pearls

• Canine pyoderma first-line: 22–30 mg/kg PO q8–12h × minimum 21 days (deep pyoderma may need 6–8 weeks)
• UTI: 22 mg/kg PO q12h × 7–14 days (uncomplicated) or 4–6 weeks (complicated / pyelonephritis)
• Take with food if GI upset — does not significantly reduce absorption
• Resistance is rising in canine staphylococci (MRSP) — culture & sensitivity at therapy start for recurrent / refractory infections
• Cefadroxil and cephalexin are interchangeable at equal doses — same spectrum, both first-gen oral cephs
• Cefovecin (Convenia) is the long-acting injectable cousin — 8 mg/kg SC q14 d for non-compliant patients
• Never use orally in rabbits or guinea pigs — fatal dysbiosis

Mechanism of action

First-generation oral cephalosporin. Binds penicillin-binding proteins (PBPs) — inhibits transpeptidase activity, preventing peptidoglycan cross-linking in the bacterial cell wall. Bactericidal, time-dependent killing. Spectrum: excellent Gram-positive (especially Staphylococcus including beta-lactamase producers — first-gen cephs are stable to staphylococcal beta-lactamase but not extended-spectrum), moderate Gram-negative (E. coli, Klebsiella, Proteus). Limited efficacy against Pseudomonas, anaerobes, Enterococcus.

Formulations and products

• Capsule 250 mg
• Capsule 500 mg
• Suspension 25 mg/mL
• Suspension 50 mg/mL
• Lixen Palatab tablet 300 mg (Virbac, pets)
• Lixen Palatab tablet 600 mg (Virbac, pets)
• Lixen IU suspension (Virbac, intrauterine for cattle)
• Lixen Palatab (Virbac) — 300 mg, Palatable tablet
• Lixen Palatab (Virbac) — 600 mg, Palatable tablet
• Lixen Tablet (Virbac) — 600 mg, Large-animal tablet
• Lixen IU Suspension (Virbac) — Cephalexin, Intrauterine suspension
• Vetalexin Tablet (Indian Immunologicals (IIL), Hyderabad) — 600 mg, Oral tablet
• Vetalexin Oral Suspension (Indian Immunologicals (IIL), Hyderabad) — 250 mg / 5 mL, Oral suspension (vanilla flavoured)
• Cephast (Micro Animal Health Care (Micro Labs group), Bengaluru) — 7.5 % w/w cephalexin, Oral powder sachet
• Cephast I.U. (Micro Animal Health Care (Micro Labs group), Bengaluru) — Cephalexin 1.5 g per 4 g vial, Intrauterine suspension
• Cephast I.U. Plus (Micro Animal Health Care (Micro Labs group), Bengaluru) — Cephalexin 750 mg + Urea 2.5 g, Intrauterine bolus
• Moxomast-200 (Micro Animal Health Care (Micro Labs group), Bengaluru) — Cephalexin 100 mg + Neomycin 100 mg + Prednisolone 10 mg per 5 g, Intramammary infusion syringe

Storage

Tablets / capsules: 15–30 °C, dry, protected from light. Oral suspension: reconstitute with water per label, refrigerate after reconstitution, discard after 14 days, shake before use.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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• Ceftazidime
• Ceftiofur
• Ceftriaxone
• Cefuroxime
• Chloramphenicol
• Ciprofloxacin
• Clarithromycin
• Clindamycin

Frequently asked questions