Convenia (Cefovecin) for Cats: Long-Acting Antibiotic Injection

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.

Convenia is the brand name for cefovecin sodium, a prescription third-generation cephalosporin antibiotic given as an injection under the skin by your vet. In cats, it is designed to provide antibiotic activity for about 14 days after one dose, which can be very helpful when giving pills at home is stressful or unreliable.

What makes Convenia different is how long it stays in the body. Cefovecin is highly protein-bound in cats and has a long elimination half-life, which is why one injection can cover a treatment period that would otherwise require many oral doses. That convenience can be a real advantage for fractious cats, multi-cat households, and pet parents who have trouble medicating safely.

Even so, Convenia is not a "one shot for every infection" medication. It works best when your vet suspects or confirms that the infection is caused by bacteria likely to respond to cefovecin. Because the drug remains in the body for weeks, your vet will weigh the benefits of easy dosing against the downside that the medication cannot be quickly removed if side effects occur.

In the United States, Convenia is FDA-approved in cats for skin infections, specifically wounds and abscesses caused by susceptible strains of Pasteurella multocida. That makes it a common option for cat bite abscesses, puncture wounds, and infected skin injuries, especially when a cat is difficult to pill.

Your vet may also use cefovecin off-label for other bacterial infections when they believe the likely bacteria and your cat's situation make it a reasonable choice. Examples may include some soft tissue infections or dental-related infections. Off-label use is common in veterinary medicine, but it should be guided by your vet's exam, the infection site, and ideally culture results when the case is complicated.

Convenia does not treat viral illnesses, fungal disease, parasites, or inflammation that is not caused by bacteria. If a cat has sneezing, coughing, urinary signs, or skin problems, the underlying cause still matters. A long-acting antibiotic may be helpful in some cases, but it is not a substitute for diagnosis.

Convenia is given subcutaneously by your vet. The labeled dose for cats is 8 mg/kg (3.6 mg/lb) once, which corresponds to about 0.1 mL/kg of the reconstituted 80 mg/mL product. In many cats, that single injection is intended to provide about 14 days of treatment.

Cats usually receive the injection in the clinic rather than at home. Peak blood levels are reached quickly, with manufacturer information noting a median time to maximum concentration of about 2 hours in cats. Improvement in swelling, drainage, pain, or appetite may take a couple of days, depending on how severe the infection is and whether the wound also needs drainage, cleaning, pain control, or other supportive care.

Because cefovecin stays in the body a long time, dosing decisions matter. The drug's half-life in cats is about 6.9 days, and the manufacturer notes it can take roughly 65 days to eliminate 97% of the dose. That is one reason your vet may be more cautious in very young kittens, breeding cats, pregnant or nursing cats, or cats with a history of antibiotic reactions. If your cat is not improving within a few days, or seems worse, contact your vet promptly rather than waiting for the injection to "finish working."

Most cats tolerate Convenia reasonably well, but side effects can happen. The most commonly reported problems are vomiting, diarrhea, decreased appetite, and lethargy. In field studies submitted with the prescribing information, these effects were generally uncommon and often mild, but they still matter because the medication cannot be taken back once injected.

More serious reactions are less common but deserve quick attention. Cats with an allergy to cephalosporins or penicillins should not receive Convenia. Rare but important reactions can include facial swelling, hives, collapse, trouble breathing, severe weakness, or anaphylaxis. Injection-site irritation can also occur. Post-approval reports have included neurologic signs, severe allergic reactions, and blood-related abnormalities, although these are not common.

Call your vet the same day if your cat has repeated vomiting, significant diarrhea, marked loss of appetite, unusual behavior, or worsening infection signs after the injection. See your vet immediately if your cat has trouble breathing, collapses, develops facial swelling, or seems acutely distressed. Because cefovecin clears slowly, some adverse effects may need monitoring for longer than with a short-course oral antibiotic.

Convenia can interact with other medications, especially drugs that are highly protein-bound in the bloodstream. The prescribing information specifically notes that cefovecin may increase free concentrations of carprofen, furosemide, doxycycline, and ketoconazole in an in vitro system. It also advises caution with other highly protein-bound drugs, including some NSAIDs, propofol, cardiac medications, anticonvulsants, and behavioral medications.

That does not mean these combinations are always unsafe. It means your vet should know every medication, supplement, and topical product your cat is receiving before giving the injection. This is especially important for cats with kidney disease, dehydration, seizure disorders, or complex medical histories.

Convenia can also affect some lab results. Cephalosporins have been associated with false-positive urine glucose, falsely elevated urine protein, positive direct Coombs' tests, and interference with some albumin measurements. If your cat needs bloodwork or urinalysis after treatment, tell your vet and the care team that cefovecin was given and on what date.