Amoxicillin / Clavulanic Acid: veterinary dose and monograph

At a glance

Drug class

Antibiotic

Also known as

Clavamox, Augmentin, Synulox

Species with doses

Dogs, Cats, Birds and Ferrets

General dose range

12.5–25 mg/kg PO q12h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Skin and soft tissue infections
• Urinary tract infections
• Dental / periodontal infections
• Upper respiratory infections
• Otitis media
• Bite wounds / infected lacerations

Amoxicillin / Clavulanic Acid 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

• Skin / soft tissue / UTI (label): Doses are combined amoxicillin + clavulanate. Plumb’s p.88: label 13.75 mg/kg PO twice daily, not beyond 30 days; UTI and skin/soft tissue 12.5 mg/kg q12h for 5–7 days, skin up to 21 days (Greene); Gram-positive 10 mg/kg q12h, Gram-negative 20 mg/kg q8h (Aucoin); UTI 12.5 mg/kg q8h (Adams). No Papich 5e amoxicillin–clavulanate dose section in the edition used.
• Deep pyoderma: Plumb’s p.88: deep pyoderma 12.5 mg/kg q12h for 14–120 days (Greene); non-superficial pyoderma 10–25 mg/kg twice daily for 3–6 weeks (max 650 mg per dose), increasing to three times daily if no response in 1 week (Aucoin); recurrent pyoderma 13.75–22 mg/kg q8–12h (Hillier); 22 mg/kg twice daily or 13.75 mg/kg q8h (Rosenkrantz). Continue 1–2 weeks past resolution.
• Bite wounds: Plumb’s p.88: skin/soft tissue 12.5 mg/kg q12h for 5–7 days (Greene); Gram-negative 20 mg/kg q8h (Aucoin); bacteraemia 22 mg/kg q8–12h for 7 days. Culture deep or infected wounds.

Cats

• Skin / soft tissue / UTI (label): Plumb’s p.88: label 62.5 mg per cat PO twice daily, not beyond 30 days; UTI 62.5 mg per cat q12h for 10–30 days; skin/soft tissue 62.5 mg per cat or 10–20 mg/kg q12h for 5–7 days (Greene).
• Dental / upper respiratory: Plumb’s p.88: 10–20 mg/kg q12h (Greene); Gram-positive 10 mg/kg q12h, Gram-negative 20 mg/kg q8h (Aucoin); sepsis/pneumonia 10–20 mg/kg q8h for 7–10 days.

Birds

• Susceptible infections (psittacines): Plumb’s p.88 (Hoeffer 1995): 50–100 mg/kg PO q6–8h; Plumb’s p.466 (Flammer 2006): 125 mg/kg PO three times daily with enrofloxacin for empirical Gram-negative therapy in psittacines. Ratites 10–15 mg/kg PO twice daily (Jenson 1998). Avian doses are much higher per kg than mammalian doses.

Ferrets

• Susceptible infection: Plumb’s p.88 (Williams 2000): 10–20 mg/kg PO 2–3 times daily (combined amoxicillin + clavulanate).

Contraindications

Penicillin / cephalosporin hypersensitivity. CONTRAINDICATED in rabbits, guinea pigs, chinchillas, hamsters — fatal clostridial enterotoxaemia. NEVER use in gerbils. Not recommended for ruminants. Use cautiously in horses.

Species-specific warnings

Dogs: Widely used first-line for pyoderma, UTI, soft tissue infection. Give with food. Minimum 21 days for pyoderma.

Cats: Useful for UTI, abscess. Same dose as dogs. Cefovecin (Convenia) is an alternative if oral compliance is poor.

Rabbits: NEVER orally — fatal Clostridium overgrowth.

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

Cattle: Some intramammary and parenteral combination products available (Synulox brand variants) — verify withdrawal periods per product.

Adverse effects

• GI: vomiting, diarrhoea, anorexia
• Hypersensitivity: rash, urticaria, anaphylaxis
• Elevated liver enzymes (rare)
• Antibiotic-associated diarrhoea / dysbiosis

Drug interactions

• Aminoglycosides (gentamicin): synergistic against Enterococcus, Listeria — but do NOT mix in same syringe (inactivation)
• Bacteriostatic antibiotics (tetracyclines, chloramphenicol, erythromycin): theoretical antagonism
• Probenecid: prolongs amoxicillin half-life via blocked tubular secretion
• Warfarin: may potentiate anticoagulation
• Methotrexate: decreased renal clearance — toxicity
• Allopurinol: increased hypersensitivity rash risk

Pregnancy and lactation

Generally considered safe in pregnancy and lactation at therapeutic doses (Category B human). Crosses placenta and enters milk in low amounts. Widely used in pregnant bitches, queens, cattle. Avoid PO route in pregnant lagomorphs / small mammals — fatal dysbiosis.

Monitoring

• GI tolerance — give with food to reduce upset
• Hypersensitivity (especially first dose) — same precautions as plain amoxicillin
• Renal function on prolonged courses
• Hepatic enzymes (ALT, ALP) if treatment exceeds 2 weeks — rare clavulanate hepatotoxicity
• Clinical response — pyoderma at minimum 21 days; UTI 7–14 days

Toxicity and overdose

GI upset (vomiting, diarrhoea) MORE COMMON than with plain amoxicillin due to clavulanate component. Hypersensitivity (urticaria, anaphylaxis) — cross-reactivity with penicillins / cephalosporins. Cats: occasional hypersalivation, vomiting. Lagomorphs / small mammals: PO route causes fatal Clostridium overgrowth — same risk as plain amoxicillin. Hepatotoxicity reported rarely (clavulanate component).

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

Clinical pearls

• Canine pyoderma: 12.5–25 mg/kg PO q12h (amox + clav combined) × minimum 21 days
• Canine / feline UTI: 12.5–25 mg/kg PO q12h × 7–14 days
• Bite wounds, abscesses, oral infection: covers most mixed aerobe-anaerobe flora at 12.5–25 mg/kg PO q12h
• Otitis externa with mixed infection: 12.5 mg/kg PO q12h + topical therapy
• Aspiration pneumonia: 20 mg/kg IV q8h Synulox RTU, often combined with metronidazole for anaerobes
• Give WITH FOOD to reduce GI upset (clavulanate adds GI burden vs. plain amoxicillin)
• NEVER orally in rabbits, guinea pigs, hamsters — fatal Clostridium dysbiosis
• Resistance is rising — culture & sensitivity at therapy start for refractory / recurrent infections
• Tablet PROTECTION: keep dry — clavulanate degrades in moisture (don't cut tablets and store)

Mechanism of action

Combination beta-lactam antibiotic + beta-lactamase inhibitor. AMOXICILLIN: binds PBPs, inhibits peptidoglycan cross-linking — bactericidal. CLAVULANIC ACID: irreversibly inhibits Type II/IV/V bacterial beta-lactamases ("suicide substrate") — protects amoxicillin from enzymatic destruction. Net spectrum: amoxicillin spectrum PLUS beta-lactamase-producing Staphylococcus aureus, many E. coli, Klebsiella, Proteus, Bacteroides, Pasteurella. The clavulanate component is the value-add: it does NOT extend spectrum against organisms that lack beta-lactamase, and adds GI side effects.

Formulations and products

• Clavamox drops 62.5 mg/mL
• Clavamox tablet 62.5 mg
• Clavamox tablet 125 mg
• Clavamox tablet 250 mg
• Clavamox tablet 375 mg

Storage

Tablets: 15–25 °C, dry, protected from light AND MOISTURE (clavulanate degrades rapidly in moisture). Oral suspension: REFRIGERATE after reconstitution, discard after 10 days. Multidose injection (Synulox RTU): refrigerate, shake well. Discard tablets if discoloured.

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.

Other antibiotics

• Amikacin
• Amoxicillin
• Ampicillin
• Apramycin
• Azithromycin
• Cefadroxil
• Cefazolin
• Cefixime

Frequently asked questions