Ampicillin Veterinarian Advice: How to Use This Antibiotic Safely in Pets

If your vet prescribed ampicillin, you probably have questions about the right dose, how to give it, and what to expect. Ampicillin is a broad‑spectrum penicillin that works well for many bacterial infections in dogs, cats, and even livestock. Below is a plain‑English rundown of the most useful tips you’ll need.

Typical Dosage and How to Administer

For dogs and cats, vets usually recommend 10‑20 mg per kilogram of body weight, given every 12 hours. Small animals like rabbits or guinea pigs get a lower dose, often 5‑10 mg/kg. The drug comes as a tablet, capsule, or liquid suspension, so pick the form your vet suggests. If you’re using the liquid, a syringe without a needle makes dosing exact—just pull the right amount and gently squirt it into the side of the mouth.

Never split tablets unless the vet says it’s okay; uneven pieces can lead to under‑ or overdosing. If you miss a dose, give it as soon as you remember, but don’t double up. Keep a dosing schedule on your fridge or phone so you don’t skip a beat.

What Infections Does Ampicillin Treat?

Ampicillin shines against skin infections, urinary tract infections, and some respiratory bugs. It’s also a go‑to for post‑surgical prophylaxis when the wound is prone to bacterial contamination. If your pet has a serious bacterial pneumonia or septic arthritis, the vet may combine ampicillin with another antibiotic for broader coverage.

Remember, ampicillin won’t work on viral infections, so if your pet’s symptoms are due to a virus, the drug won’t help and could cause unnecessary side effects.

Side Effects to Watch For

Most pets tolerate ampicillin well, but keep an eye out for vomiting, diarrhea, or loss of appetite. A mild rash or itchiness can also appear; this usually means the animal is allergic. If you notice any swelling around the face, trouble breathing, or a sudden drop in energy, call your vet immediately—those could be signs of a severe allergic reaction.

Long‑term use can sometimes affect gut flora, leading to overgrowth of yeast. If you see a thick, white coating in the mouth or a recurring yeast infection, ask the vet whether a probiotic supplement would help.

Storage and Shelf Life

Ampicillin tablets should stay in a cool, dry place, away from direct sunlight. The liquid suspension is trickier; once opened, it usually lasts 14 days in the fridge. Toss any leftovers after that period—old medicine can lose potency and become a breeding ground for bacteria.

Never share your pet’s ampicillin with another animal, even if they have the same symptoms. Different species can react differently, and the dose may be off.

Tips for a Smooth Treatment

Give the medication with food if your vet says it’s okay; this can reduce stomach upset. For hard‑to‑swallow pills, you can hide them in a small amount of wet food or a cheese bite—just make sure your pet eats the whole treat.

Schedule a follow‑up appointment after the course ends. The vet will usually want a check‑up to confirm the infection cleared and decide whether a repeat course is needed.

Using ampicillin correctly helps your pet bounce back faster and reduces the chance of antibiotic resistance. Follow the vet’s instructions, watch for side effects, and you’ll give your animal the best chance at a quick recovery.