Convenia For Cats: A Unique Long Lasting Injectable Antibiotic For Cats

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Convenia Injection for Cats

As a vet writing in the media, I try to stay away from writing about prescription only products: these, by definition, can only be given after a vet has decided that they are clinically indicated.

Convenia For Cats Overview

Medication Type:
Prescription Required?:
FDA Approved?:
Life Stage:
4 Months Or Older
Brand Names:
Common Names:
Cefovecin Sodium
Available Dosages:
Expiration Range:
56 Days Refrigerated (Reconstituted)

If cat carers read about prescription only products and then feel motivated to ask their vet to use them for their pets, this carries the risk of placing undue pressure on vets. So I need to be clear at the start of this article: it is for a veterinarian to decide to use prescription products, not an owner.

That said, my mission in life is to communicate veterinary science to animal carers. I believe that if a drug is given to an animal, prescription or otherwise, it can only be helpful for an owner to understand more about the drug. The more information people have, the more likely they are to be able to help their pets with the help of their veterinarians.

With this proviso, this article is about a widely used product in feline medicine, an antibiotic called cefovecin, known more commonly by its brand name, “Convenia”.

What Is Convenia

Convenia is a widely used third generation cephalosporin antibiotic marketed by the largest multinational animal health company in the world, Zoetis (formerly Pfizer).

Convenia is an injectable antibiotic with a unique formulation which means that one injection lasts for a full two weeks (most injectable antibiotics are only effective for 24 hours).

It’s this aspect that gives the product such a talking point and a high profile; so many owners have difficulty giving medication to their cats, and it’s a significant benefit to be able to give the equivalent of two weeks of twice daily tablets in a single injection.

What Is A Third Generation Cephalosporin Antibiotic?

Antibiotics, by definition, kill or inhibit the growth of microorganisms including bacteria. Cephalosporins are a particular group of antibiotics: they are bactericidal (i.e. they kill bacteria rather than just inhibiting their growth), and they are known as beta-lactam antibiotics because they contain a beta-lactam ring in their molecular structure. They kill bacteria by inhibiting enzymes in the cell wall of susceptible bacteria.

There are five generations of cephalosporins, with each generation having different properties to the previous one. This is a similar concept to the different iteration of iPhones: the original iPhone was first generation, and the latest model – the iPhone 11 – is the eleventh generation.

What Is Convenia Used For In Cats?

Convenia should only be used in situations where cats require a full fourteen day course of antibiotics, and in particular Convenia is useful in situations where it is difficult or impossible to give a cat normal oral antibiotics (such as tablets).

Convenia is most commonly used for the prolonged treatment of skin and soft tissue infections, for infections of the urinary tract, and as part of the management of severe periodontal disease. It generally has good efficacy against the bacteria commonly associated with these conditions.

Vets may sometimes give owners a choice between a course of antibiotic tablets (which may be less expensive, but which may be less easily administered) or a single injection of Convenia.

The drug is not as highly effective as some other antibiotics against some bacteria (e.g. Pseudomonas) so it is a decision for the vet as to whether or not Convenia is an appropriate choice for a particular case.

What Dose Of Convenia Is Given To Cats?

Convenia is sold to vets as a powder inside a sterile bottle: this is made up into a solution by the addition of a reconstituting solution. This needs to be kept in the fridge, and should be used within 28 days. The dose per cat is weight-related, at a rate of 0.1ml per kg, injected sub-cutaneously, usually into the scruff of the neck. Some cats (e.g. patients with renal failure) may require a lower dose: this is a judgement for the prescribing veterinarian to make.

Dosing Table For Convenia

Animal WeightVolume To Be Administered

How Long Does Convenia Take To Work In Cats?

The antibiotic is normally absorbed into the circulation from the injection site within two hours, producing high levels in the blood stream which last for two weeks.

This long lasting effect is made possible because of high levels of binding of the drug to proteins in the blood stream which prevent it from being rapidly metabolised and excreted in the same way as most injectable antibiotic preparations.

Does Convenia Have Any Side Effects In Cats?

Most cats show no side effects after treatment with Convenia, but nearly all medications have a long list of possible side effects, and Convenia is no different. This is one of the reasons why many medicines are prescription-only: vets need to weigh the appropriateness of a product for a particular patient, taking many factors into account, including potential side effects for certain individual animals.

So-called hypersensitivity reactions (such as allergies or auto-immune problems) to Convenia can occur but they are rare. Occasionally, blood cell abnormalities may be seen following high doses.

In cats, other side effects of Convenia that are rarely seen include vomiting, diarrhoea, anorexia, lethargy, hyperactivity, inappropriate urination and mild elevations of liver and kidney enzymes (the liver metabolises Convenia, while the kidneys excrete its by-products in the urine).

Other very rarely recorded side effects include salivation, itchiness, injection site reactions, swelling of the face, ataxia (unsteadiness), tremors, seizures, and exceptionally rarely, death.

It’s easy to worry excessively when reading a list of potential side effects like this, but it should be stressed that Convenia has been very widely used for over a decade, and has a long established record of complete safety in the very high majority of cases. Studies have shown that even when dose rates of over seven times normal have been given, the drug has been well tolerated by cats.

How Much Does Convenia Cost?

Convenia is given as a prescription only medicine by vets, so the supply chain comprises manufacturer to wholesaler to veterinary clinic.

The price paid for Convenia by pet carers depends on the pricing structure operated by each of these three entities, and varies from location to location. If you are concerned about the cost of Convenia, you should ask your vet for an estimate before the injection is administered.

In general, Convenia is likely to be more expensive than an equivalent course of antibiotic tablets: it would be expected that a premium of some type would be payable for the convenience of not having to give twice daily tablets for two weeks to an unwilling cat.

Cost Of Convenia – Explanation Using Fictional Sums As Example
$10.0030% mark up means $13.0030% mark up means $16.90

Is Convenia Suitable For All Cats?

Convenia is widely used across the cat population, with a few provisos.

  • First, it is not normally recommended in kittens less than 8 weeks of age.
  • Second, safety has not been proven in pregnant or lactating cats.
  • Third, a reduced dose should be given if cats with renal failure are being treated.
  • Fourth, and obviously, it should not be given to cats with known hypersensitivity to β–lactam antibiotics.
  • Convenia is safe for older cats, but as stated previously, this decision is for a vet to make rather than the owner.

Are There Any Other Nuggets Of Important Information About Convenia?

The veterinary community welcomed Convenia when it was launched in 2007: it won an “Easy To Give” award from the iCatCare website.

Convenia continues to be widely used and appreciated by feline veterinarians, helping to ensure a high level of compliance with courses of antibiotics (owners may not give a full course of tablets due to difficulties with giving their pets tablets: this is not an issue with Convenia).

Convenia is not a panacea, and should only be used after careful consideration by veterinarians, but it’s an exceptionally useful formulation that has significantly improved the veterinary profession’s antibiotic armoury for feline patients.


About Dr. Pete Wedderburn, DVM

Dr Pete Wedderburn qualified as a vet from Edinburgh in 1985 and has run his own 4-veterinarian companion animal practice in County Wicklow, Ireland, since 1991. Pete is well known as a media veterinarian with regular national tv, radio and newspaper slots, including a weekly column in the Daily Telegraph since 2007. Pete is known as "Pete the Vet" on his busy Facebook, Instagram and Twitter pages, regularly posting information on topical subjects and real-life cases from his clinic. He also write a regular blog at His latest book: “Pet Subjects”, was published by Aurum Press in 2017.

30 thoughts on “Convenia For Cats: A Unique Long Lasting Injectable Antibiotic For Cats

  1. JAN

    I have concerns about my cat who was given Convenia injection on Thursday and I had to have her put to sleep on Friday night. She went into cardiac arrest which made it difficult for her to breath. She had not had these problems until she received this injection. After reading some of these reviews I can’t help but believe that this injection caused my cat’s death. She was 15 years old, would be 16 in August, had lived a good life and now is gone. She was given this along with a steroid injection vetalog. I pray that if this is what caused her death that those who are responsible will pay.

    1. sandy yates

      I become a cat lover about a year ago after my grandson brought home this little baby kitty! We thought it was a boy and name him Toast Master. Well 8months into it we found out he was a she and we had kitties and change her name to Toastie . Now we have 7 kitties we have been a very happy little family till our Patches started sneezing and coughing and I was scared to death to see so much discharge come from her nose So I took her to the vet They gave her a shot of Convenia I have been reading up about the sneezing and discharge and the Convenia What I have read really concerne me because I haven’t found anything yet that says that the injection of Convenia is used for a cold and I wasn’t told by the vet how Patches could pass this on to everyone else and now I have 7 kitties sneezing and coughing and lots of discharge Everyone is now sick and seam to be suffering I have no idea how to help them and I feel horrible Am mad as hell at vet for not informing me how fast this cold could spread among my babies. Patches is not getting better and I have spent a lot of money and I am scared that the Convenia might hurt her and if I take everyone else to the vet they will just give them the same thing. Is the injection of Convenia What my kitties need is it going to make them well and feel better?? I don’t know what to do I don’t know how to help them

    2. Lau

      My cat also took a 14 days convenia injection last Tuesday and on Wednesday was put to sleep, she suffered throughout the night with bad reaction which caused pulmonary edema, I took her in because she had toothache and was supposed to have the tooth extracted, her blood test came all clear and she was fit for the surgery, she had no other health problem, I’m heartbroken and the next day I took her in, the vet took a xray and said she had fluid in her lungs and claimed she always had that, he will never admit it was because of the convenia, the primary and fatal side effect of convenia is pulmonary edema, I feel so helpless and my cat is gone 🙁

      1. Pete Wedderburn DVM Post author

        I am so sorry to hear about the loss of your cat. The problem in a case like this is that it is very easy to confuse correlation with causation e.g. if a cat with hidden underlying pulmonary edema was given an injection of convenia, and the pulmonary edema got worse over a day or two, this would be “correlation”, but it would be very easy to believe that it was “causation” (i.e. to believe that the convenia caused the edema, when in fact it had nothing to do with it). Unfortunately, without xraying a cat before giving convenia, it’s impossible to be sure about a situation like this. The best that can be done would be for you to ask your veterinarian to send a “possible adverse reaction” report to FDA and also directly to the manufacturer. Over time, if there were a number of reports of possible edema reactions, then this would be added as a warning on the product data sheet. All I can say is that that type of reaction, if it did happen, would be unexpected and exceptionally rare, not that this helps your loss, I’m afraid. Again, my sympathy.

    3. Chuck Larence

      It was the steroid injection.i had a cat that almost died from one.ill never let them do another cat.

  2. Kristen S

    I’m struggling with whether Covenia had anything to do with the death of my cat. On Saturday, he began refusing food, but still drinking water, and seemed off so I took him to the vet. They ran bloodwork and thought he had a UTI. He did have kidney disease but based on his numbers she thought he just needed fluid and an antibiotic. She gave him the shot of Covenia and I gave subcutaneous fluids at home as well as syringe feeding with lots of water mixed in. By early Sunday morning, he began having horrible bloody diarrhea and bloody urine. I took him to an emergency vet where they prescribe Metronidazole to help with the diarrhea. Each day he continued to get worse, refusing all food and water, consistent diarrhea, hiding, weakened legs, and finally on Wednesday evening he began twitching his head, which lead to having massive seizures, one right after another non stop. We made the hardest decision of our lives to put him down. My vet does not think the diarrhea was a result of the Covenia, but based on the timeline of it, I just don’t buy that. I understand no one can predict how an animal will react to different medications, I’m not trying to blame anyone or anything. I guess I am just trying to give myself closure to understand what happened to my sweet boy.

    1. Pete Wedderburn DVM Post author

      Hi Kristen. I am so sorry to hear about your poor cat, but I think it is unlikely, from what you have said, to be anything to do with Convenia. The issue here is “correlation” vs “causation”. It is clear that your cat was sick, which is why you took him to the vet, and why they gave Convenia. When he then became even more seriously ill, it is far more likely that this was a continuation and aggravation of the initial underlying problem, rather than something new and separate that the Convenia caused. I am afraid there are many, many possible causes of diarrhea and bloody urine, some of them so serious that cats die, and it can be frustratingly difficult to pinpoint precisely what is going on. A wide range of tests, from urine (including culture) to blood (biochemistry and cell counts) to diagnostic imaging (right down to CT and MRI scans) are needed to work up these cases to their optimum level sometimes, and that is very pricey, and not always available. And ultimately, when your boy had passed away, then an autopsy, unfortunately, is the only way to be clear about what happened. Most people are too upset to allow this to happen, understandably, but without that, it can be impossible to get definite answers, and I am afraid that this can make it difficult to achieve full closure. My sympathy to you at your loss. A very difficult time.

  3. Frank Ferris

    My cat, Willy (13 y/o), has had an ongoing ear infection since August. I’ve used ointment, ear drops and ear wash to no avail. All treatments have been difficult to administer as Willy is not a good patient. Finally, he was given an injection of Convenia which seemed to work but after 14 days the ear condition (wet discharge, ear odor, head shaking/scratching) returned. My vet administered a second Convenia injection but, once again, the infection has returned. Any suggestions of another antibiotic that can be administered (preferably via injection) that might resolve his condition would be greatly appreciated.

    1. Stephanie

      Sounds like yeast infection in the ear (if it smells). Super easy to treat. Been in rescue for 18 years and think I have seen it all. Try some Otomax (for dogs but we use it on cats), various other ointments a vet can prescribe. I have a country vet so the cost is low – maybe $6-14 a tube. If the ears smell, its yeast. I use Convenia a lot in rescue but never for ear issues.
      Good luck!

  4. Mitch

    I’m very nervous reading these. My cat went to the vet on Tuesday and everything was good. The vet believes it due to her gingivitis that she lost a pound since last March. So he said to give her an antibiotic (convenia) and steroid to help her eat more. Actually she’s eating less now and not drinking as much. I can’t get her to eat her food but she is taking treats and drinking some water. I’m taking her back to the vet tomorrow to get her weight checked as on Tuesday she was 6.4 on. I’m kind of frustrated as the vet didn’t share the side effects about not eating. I’d never have given her that if I’d known as his concern was she’s lost weight.

  5. Christian Turner

    My kitty was found bleeding from her vagina 2 nights ago, i immediately ran her to the emergency vet. The vet administered a .35 injection of Covenia and sent me home with prazosin, buprinex and meloxicam to give her. She hasnt eaten a thing since, they also drained her bladder which was colored as blood and urine mixed, so an obvious UTI. As of now, we have cleared out a small space in the house for her to be alone in with both wet and dry food and plenty of water. she at times gets up to drink, but won’t eat. I was told by the vet to halt the meloxicam and other pain meds and see if she comes around, so praying through the night as of now. I am however still giving her the antibiotics they sent home with me by syringe. its just a chore to get her to take it. She’s completely lethargic and non active at all.

      1. Rie

        This morning I noticed my cat did not touched his food. So I went to the Clinic and the showed me his teeth and found something that looks like a Cavity. I mentioned about the sneezing with white and red like mucous and that my cat keeps swallowing. Vet said he will inject something to make him feel better and it will last for 14 days which is the Convenia. I trusted him of course, he is a Vet. Bought a tiki brand salmon wet food mixed with pumpkin puree, he is eating now, but did not see any poop but saw little amount of urine. He is always under the bed too. So I googled Convenia and Metacam and I was shocked with all the negative comments about Convenia. Now I am so scared and I couldn’t sleep at all. I keep checking on him. I read that it will be in his system up to 65 days! He did blood work too but will know the result tomorrow. Should it be bloodwork first before any shots? I really don’t know what to think and do now. It is stressing me out. He is a very active cat, he plays almost 24/7 but now he is quiet after visiting the Vet. Can you please enlighten me Dr. Pete. Thanks in advance.

        1. Dr. Pete Wedderburn, DVM Post author

          Convenia is a long acting antibiotic that is often given to cats that show all sorts of signs of illness. My opinion is that nearly all of the negative online reports that you see are, in reality, the underlying illness that the cat already had, becoming more severe as time passes, not because of the Convenia, but because the illness is not responsive to antibiotics, so the cat naturally is getting worse. People blame Convenia unfairly: this is correlation, not causation. I do not, and have never, received any money from the manufacturer – this is my honest opinion as a veterinarian. No need for blood work before antibiotics. Hope this helps a bit. Please continue to trust your vet.

        2. gann

          Hi Rie,

          How’s your fur-baby now? I hope everything is good. My cat is currently experience lethargy after the vaccine. I’m so worried.

  6. gann

    I noticed my cat totally change after the vaccine Covenia. He is just always sleeping and not active, but appetite is normal. It’s been 2 days. I’m worried anyone who experience it? My vet told me that there’s no side effect but when I saw it one of the side effects is lethargy which I think my cat is currently experiencing. I don’t know what to do.

    1. Mallory Crusta

      Hi there. It’s difficult to say whether the lethargy is a side effect of the antibiotic or related to something else. I would bring your cat into the veterinarian for evaluation. If possible, present a log of your cat’s behavior before and after they received the Convenia injection.

      1. Debbie Vernon Ph.D.

        Hi, I care for a sweet feral tortie who lives on my patio. She started coming around to my apartment around 4 years ago and had already been ear tipped. I’ve gotten to know her behavior patterns really well. In February, she was very sick. Disappeared for 3 days in extreme cold and heavy snow. When she returned, I wrapped her in a towel, put her in my old dog crate away from my other 3 cats until I could find a vet who would treat a feral cat, no matter how friendly. I wasn’t happy that they tested her for her FIV along with other common feline diseases. She was negative on everything but was FIV +. She had an upper respiratory infection and was given an injection of Covenia (she had lost weight, normally around 7lbs, she was 5.5 lbs.). Covenia was the best choice for her symptoms URI, and the fact that she is feral. She did need to get a 2nd dose 2 weeks later. As the weather was so poor, I kept her inside for a good 3 weeks or so. She was near death 2 months ago. She disappeared for a week. No one had seen her. She let’s me put my hands on her so I can tell if there is an injury. But she went in her bed, limp. Wouldn’t eat. Another URI. The vet gave her Covenia again, along with DepoMedrol, SubQ fluids, and Vitamin B Complex Inj. She also had A/D rx canned cat food I had to syringe feed her. After 24 hours, I didn’t have to syringe feed her, but it took a good week for her to bounce back. Covenia is a lifesaver for community cats. I wish it wasn’t such a short shelf life as it would be nice to have rx on hand for FIV flare-ups due to compromised immune system. Single dose pre-filled syringes to have on hand. The “cocktail” that works for her. But some vets don’t find feral cats worth the trouble. Sure, TNR programs exist, but once that’s done, no care exists.

  7. Yulia

    My Sphinx cat received this injection today , after I read all the comments I was shocked. The vet was very unprofessional, she never said anything or educate before administration, and my cat came at clinic for URI After reading everything now I just worry. If there side effects to medication, when they usually can be noticeable? Is there safe time if nothing happened, that most likely there is no reaction to medication or they can happen anytime starting from 2-4 hours after administration up to 65 days?

    1. Dr. Pete Wedderburn, DVM Post author

      My sense is that many people confuse “correlation” with “causation” when it comes to Convenia. The injection is often given to cats where the diagnosis is not certain, but a bacterial infection is suspected. The injection will only be effective if the cause of the illness is, indeed, a bacterial infection, so if there is any other cause, the injection will not cure it. So it is not surprising that the injection is often given, and illness follows. This does not mean that the injection causes the illness. However, if your cat does show any of the signs listed above (vomiting, diarrhoea, anorexia, lethargy, hyperactivity, inappropriate urination, salivation, itchiness, injection site reactions, swelling of the face, ataxia, tremors, or seizures) then you should mention this to your veterinarian, who may then report the case as a possible adverse reaction to the medication. I stress that this is extremely rare, and so it is very unlikely to happen.

  8. Michelle Morse

    Mine started 2 weeks ago with not eating or drinking much of anything at all, took her to her vert and they gave fluids, mirataz, and anit nausea med. After 13 days she seemed worse not urinating or pooping, so called vert and took her to there other office on Monday. They dx her with UTI and gave her Buprenorphine SR 3mg, Convenia, and sent use home with another appetite. 36 hours later and she is eating well, but not using the litter box at all and seems very agitated, not sleeping just stands at the top of the stairs. After reading what convenia was i am now concerned if the combination of Buprenorphine and Convenia is causing her issues, she also looks bloated and eyes are very dilated.

    1. Dr. Pete Wedderburn, DVM Post author

      Convenia is a long acting antibiotic, while buprenorphine is a pain killer, so they would work well together and would be very unlikely to cause the signs you describe. It’s far more likely that the underlying condition is the cause of her oddness. Hopefully this will have settled down by now.

  9. Vivian

    You killed my cat of 9 years with this convenia injection and this buprenorphine injection.
    He went to the vet 8/27/20 and died 4/24/21, he went for a tooth infection. He had blood work
    done cells, kidney, liver, anemia and it came back all normal? His eating habits were never the same after treatment and he slept continuously. That was my little bud and the way he died will never sit right with me. He was on a chest and my back to him on the phone, he slammed into the back of my calves and pushed my knees forward, he let out a horrible scream and laid there at the base of my foot. He took three last struggling breaths and was gone. If you people do not know what you are doing, then get out of medicine. We see this constantly with humans and animals. Thanks for killing my cat!

    1. Mallory Crusta

      Hi Vivian, that sounds incredibly disturbing and worrying. This warrants further investigation, so please don’t be hasty in assuming that the Convenia was responsible for your cat’s death. I hope that you will pursue further information on what happened rather than pointing directly to the injections. Please discuss this incident with both your vet and others, and hopefully, you’ll be able to identify exactly what happened.

  10. Techy

    Question: My kitten of 5 months was prescribed Clindamycin plus Convenia and maloxam thensent home yesterday with 106F of fever.
    Can those two antibiotics be prescribed together? Thank you.

  11. Holly King

    Vets give this and use the excuse that owners aren’t smart enough to give other meds. Unfortunately I have a job where I couldn’t be home for the initial appt for a damaged nail bed. They chose to give this to my cat, and I didn’t get to speak to the vet before this convenia was administered. A long time customer at this vet office.I have a sick kitty now and only after I have investigated, and knew that nothing in my home caused the symptoms. The vet office made a big production that it might have been accidental poisoning from my home.
    It was the reaction of convenia. A conveince for who?


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