Vet Guide to Amoxicillin in 2025 🐾

Hi, I'm Dr Duncan Houston, BVSc, founder of Ask A Vet. In this detailed 2025 guide, we'll cover everything you need to know about amoxicillin: what it is, how veterinarians use it in dogs and cats, recommended dosing, possible side effects, safety tips, monitoring protocols, and when to seek help.

📘 What Is Amoxicillin?

Amoxicillin is an aminopenicillin antibiotic in the penicillin family. It works by disrupting the bacterial cell wall, causing the bacteria to die :contentReference[oaicite:3]{index=3}. FDA-approved for use in both dogs and cats, it's an essential tool in treating bacterial infections :contentReference[oaicite:4]{index=4}.

✅ Common Veterinary Uses

Amoxicillin treats a wide range of bacterial infections, including:

• Skin and soft tissue infections (abscesses, cellulitis) :contentReference[oaicite:5]{index=5}
• Respiratory tract infections (pneumonia, kennel cough) :contentReference[oaicite:6]{index=6}
• Urinary tract infections—especially cystitis in dogs and cats :contentReference[oaicite:7]{index=7}
• Dental infections, wounds, and sometimes gastrointestinal infections :contentReference[oaicite:8]{index=8}

📐 Dosing & Administration

Dosing depends on species and condition—follow your veterinarian’s guidance:

• Cats: 10–25 mg/kg orally every 12 hours, often as liquid suspension :contentReference[oaicite:9]{index=9}
• Dogs: 10–25 mg/kg every 12 hours (approximately 5–12 mg/lb) :contentReference[oaicite:10]{index=10}

Can be given with or without food. If GI upset occurs, administer with meals :contentReference[oaicite:11]{index=11}.

🗓️ Completing the Course

Always finish the full antibiotic course—typically 7–14 days, or as directed—even if symptoms improve, to fully clear the infection :contentReference[oaicite:12]{index=12}.

⚠️ Side Effects & Reactions

Common

• Vomiting, diarrhea, decreased appetite, mild lethargy :contentReference[oaicite:13]{index=13}
• Skin rashes, ear irritation, facial swelling—a sign of penicillin allergy :contentReference[oaicite:14]{index=14}

Rare / Serious

• Anaphylaxis (rare but life-threatening)—collapsing, difficulty breathing :contentReference[oaicite:15]{index=15}
• Kidney changes, severe diarrhea, seizures with large overdose :contentReference[oaicite:16]{index=16}

🧬 Special Precautions

• Not suitable for herbivores like rabbits—can cause fatal diarrhea :contentReference[oaicite:17]{index=17}
• Avoid in pets with penicillin allergy or history of antibiotic reactions
• Modest dose adjustment may be needed for pets with kidney issues :contentReference[oaicite:18]{index=18}

🧪 Monitoring & Follow-up

• Watch for improvement in 48–72 hours. If symptoms worsen, call your vet.
• No routine bloodwork required for short courses unless your vet advises it.
• If diarrhea occurs, discuss probiotics or dietary changes with your vet.

⏰ What if You Miss a Dose?

Give the missed dose as soon as you remember, unless it's close to the next scheduled dose—then skip it. Never double-dose :contentReference[oaicite:19]{index=19}.

🚨 Overdose & Emergency

Overdose can cause vomiting, diarrhea, kidney issues, and rarely seizures or coordination problems :contentReference[oaicite:20]{index=20}. Contact your vet or call Pet Poison Helpline (855‑764‑7661) or ASPCA (888‑426‑4435) immediately if you suspect an overdose.

🛡️ Comparative Note: Amoxicillin vs. Amoxicillin-Clavulanate

The combination with clavulanic acid (brand name Clavamox®, Augmentin®) expands coverage to resistant infections, especially those caused by beta-lactamase producing bacteria—used for tougher skin, dental, or deep tissue infections :contentReference[oaicite:21]{index=21}. Side effect profile is similar :contentReference[oaicite:22]{index=22}.

🏡 Common Scenarios

🐶 Dog with UTI

• Sample urine for culture and sensitivity
• Give amoxicillin 12.5 mg/kg PO q12h for ~10–14 days based on lab results
• Recheck urine after completion to confirm resolution

🐱 Cat with Upper Respiratory Infection

• Administer liquid amoxicillin 15 mg/kg PO q12h for 7–10 days
• Shiver and fridge suspension; ensure fluid intake and monitor appetite

❓ FAQs

Can I use a human amoxicillin pill?

Human formulations can be used under vet advice but ensure correct dose, quality, and flavor form :contentReference[oaicite:23]{index=23}.

Will it treat all infections?

No—only bacterial infections sensitive to penicillin. For resistant strains or mixed infections, your vet may prescribe alternatives.

Can I stop early if symptoms improve?

No—finish the full course to prevent relapse and antibiotic resistance.

📌 Final Takeaways

• Amoxicillin is a reliable, safe, and cost-effective aminopenicillin antibiotic for many bacterial infections in dogs and cats.
• Typical dosing: 10–25 mg/kg every 12 hours for 7–14 days.
• Minor side effects include GI upset and less commonly allergic reactions.
• Finish the full course, watch for reactions, and seek help if symptoms worsen.
• Consult your vet before giving any human-formulation medications.

Need help implementing amoxicillin or exploring alternatives for your pet’s infection? Ask A Vet is available 24/7 to offer individualized treatment plans and guidance. Download the Ask A Vet app now for trusted veterinary advice anytime. 🐶🐱❤️