Amoxicillin for Dogs & Cats: Uses, Dosage & Side Effects

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Amoxicillin is a penicillin-family antibiotic used in dogs and cats to treat certain bacterial infections. A related product, amoxicillin-clavulanate, combines amoxicillin with clavulanic acid or clavulanate potassium. That second ingredient helps the medication work against some bacteria that would otherwise break down plain amoxicillin.

In veterinary medicine, amoxicillin-clavulanate is commonly prescribed under brand names such as Clavamox and as generic tablets or oral suspension. It is a prescription medication, and your vet chooses it based on the likely bacteria involved, the body system affected, and your pet's age, weight, and medical history.

This drug does not treat viral infections, fungal infections, or every possible bacterial infection. That is why your vet may recommend cytology, a urine test, or a culture and susceptibility test before or during treatment, especially if the infection is severe, recurrent, or not improving as expected.

Vets use amoxicillin or amoxicillin-clavulanate for a range of susceptible bacterial infections in dogs and cats. Common examples include skin and soft tissue infections, bite wounds, abscesses, periodontal infections, and some urinary tract or respiratory infections. In dogs, labeled uses for amoxicillin-clavulanate include periodontal disease and skin or soft tissue infections. In cats, it is often used for skin and soft tissue infections and abscesses.

Your vet may choose plain amoxicillin in some situations and amoxicillin-clavulanate in others. For example, Merck notes that amoxicillin is often considered a first-line option for sporadic bacterial cystitis, while clavulanate may be added when broader coverage is needed or when resistant bacteria are a concern.

The best use depends on the infection site and the bacteria involved. If your pet has a deep wound, repeated urinary issues, pneumonia, or a history of antibiotic-resistant infection, your vet may recommend culture testing so treatment is more targeted and antimicrobial use stays responsible.

Always follow the label and your vet's instructions. Do not calculate a dose from human amoxicillin products on your own. Veterinary dosing varies by formulation, infection type, and your pet's kidney or liver function. For amoxicillin-clavulanate, a commonly referenced veterinary dose is 13.75 mg/kg by mouth every 12 hours for 5 to 7 days, but some infections need different durations or a different antibiotic altogether.

Amoxicillin-clavulanate is available as tablets, chewable tablets, and oral suspension. It can often be given with or without food, but giving it with a small meal may help if your pet gets stomach upset. If your vet dispenses the liquid form, shake it well and measure carefully with the provided syringe or dropper.

Finish the full course exactly as prescribed unless your vet tells you to stop. Skipping doses, stopping early, or using leftover antibiotics can make treatment less effective and may contribute to antimicrobial resistance. If you miss a dose, contact your vet or pharmacist for guidance rather than doubling the next dose.

The most common side effects are digestive upset, including vomiting, diarrhea, soft stool, reduced appetite, or drooling. Many pets tolerate the medication well, but stomach signs are more likely if the dose is high for that pet or if the medication is given on an empty stomach.

Some pets can have an allergic reaction to penicillin-type antibiotics. Warning signs may include facial swelling, hives, itching, sudden vomiting, trouble breathing, collapse, or severe lethargy. See your vet immediately if any of these happen.

Call your vet promptly if your dog or cat stops eating, has repeated vomiting, develops severe diarrhea, seems much more tired than usual, or is not improving after a few days. Pets with kidney or liver disease may need closer monitoring because the drug can last longer in the body.

Amoxicillin and amoxicillin-clavulanate can interact with other medications, supplements, or treatment plans, so your vet should know everything your pet is taking. That includes prescription drugs, over-the-counter products, probiotics, compounded medications, and flea, tick, or heartworm preventives.

Potential concerns include other antibiotics, drugs that may affect kidney function, and medications that can change how antibiotics work in the body. In some cases, your vet may intentionally combine treatments, but that decision should be based on the infection, culture results, and your pet's overall health.

Tell your vet if your pet has ever had a reaction to penicillins or cephalosporins, because cross-reactivity can occur. Also mention pregnancy, nursing status, kidney disease, liver disease, or a history of repeated antibiotic use, since those details can change the safest and most practical treatment plan.