# Has anyone's cat had a convenia injection?



## Jay1993 (May 10, 2016)

Hi, my cat had a fight with another cat and her ear was bit on the ear by a cat, unfortunately pus started to come out of her ear from a scab so went to the vet to get her treated. We were asked if our cat would have oral medication but our cat will do her best to avoid it so they said they can give her injection. We did not think much to it until they provided a receipt and on there it showed she had a Convenia Injection 80mg, so curiosity got the better of me and I searched on the internet for it. There were a lot of horror stories on the internet which is not too surprising with the internet but I was a little concerned about the number of people reporting death of their cats due to this injection and some groups wanting the injection banned.

Obviously the internet can sometimes exaggerate so I am just wondering if anyone's cat on her has had a convenia injection? And if so what was there experience of it with there cat?

My cat is two days into the injection so far, she does seem a little more lethargic than usual but not by a whole lot, her appetite etc is all fine, so far she seems to coping ok with it.


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## OrientalSlave (Jan 26, 2012)

If she is fine now then she's not going to get a reaction to the antibiotic.


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## chillminx (Nov 22, 2010)

A couple of my cats have had a Convenia injection in the past. They were fine. 

My vet says she has never yet had a cat react badly to Convenia. I know the vets generally like to reserve use of it for more serious cases of infection, and use oral ABs instead where feasible..


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## QOTN (Jan 3, 2014)

Many of my cats have had convenia injections. My vets use it for certain conditions. None of my cats have ever had a problem afterwards including one who had three injections at two week intervals for a particularly bad case of feline acne. The trouble with a long lasting injection is that nothing can be done if the cat has a bad reaction to the drug but my vet has never known such a case. It sounds as though your cat is one of the majority and can tolerate it very well. Any lethargy is probably an indication her body is tackling the infection.


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## Matrod (Dec 22, 2014)

My two have had them quite a few times & never had any issues, one of them has had 2 injections a fortnight apart. I think it's important to remember you only hear about the things that go wrong on the Internet rather than the millions of other cases where there have been no reactions.


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## Ceiling Kitty (Mar 7, 2010)

Copied from another thread on the subject:

This is such an interesting and important topic. I have a lot of respect for Lisa Pierson; I've never seen this article before (I have mainly read the dietary information on her site), but I just read it now and have a few points I'd like to add, specifically for UK forum users (Dr. Pierson is based in the States).

First, the reporting system for the UK is obviously specific to us. If you believe your cat has had, or might have have, an adverse reaction to a medication (any medication, not just Convenia), you need to report it to the Veterinary Medicines Directorate (VMD). You can do this here by filling in an online form:https://www.vmd.defra.gov.uk/adversereactionreporting/?AspxAutoDetectCookieSupport=1 If you wish, you can also report it directly to Zoetis, who manufacture the drug. Their contact details are in the link at the bottom of my post.

Second, Dr. Pierson's article discusses the use of Convenia for urinary tract infections in cats. It's important to note that in the UK, Convenia is licensed for the treatment of urinary tract infections - specifically those caused by _E.coli_ - as well as skin infections (this is not the case in the States).










Regarding the side effects reported with Convenia, Dr. Pierson quite rightly points out that all drugs have side effects. Convenia is a drug called cefovecin, which is in a class of antibiotics called cephalosporins. Both cephalosporins and their close relations the penicillins are known to potentially lower the seizure threshold, and several are known to cause suppression of blood cell production in the bone marrow. These are of note when you consider that many of the reports of adverse reactions to Convenia in cats focus on neurological symptoms (seizures and ataxia) and anaemia. It's something of a puzzle to me why a cephalosporin should affect a healthy brain in such a way, since technically they cannot cross the blood-brain barrier, but we know it happens. I'd be lying if I said I knew the mechanism.

As in humans, penicillins and cephalosporins can also be associated with severe allergic reactions, even as bad as fatal anaphylactic shock. This can happen with almost any drug, if that individual is sensitive to it.

These side effects (and more) are listed in the product SPCs (Summary of Product Characteristics):










It is the duty of the veterinary surgeon caring for the cat to ensure the owner is informed of possible side effects when prescribing a medication, but we need to be realistic. If vets listed every possible side effect of every medication they dispense, consultations would end up being twice as long and lots of cats would probably go without treatment because their owners are too scared of the risks. The detail with which side effects are discussed must depend on the frequency and severity of the side effect. It might be forgiven if the vet didn't mention a rare, mild side effect (like mild skin irritation) that can occur. But if they fail to mention a more common, severe one (such as seizures), then it can be argued that the owner did not provide their_ informed_ consent. It's important that risks are discussed, but with a modicum of common sense.

Look at the bottom of the information on adverse effects, though:










Convenia is licensed to be given every 14 days for a total of two injections. They tested safety by giving cats a five times' overdose for eight injections, and report that it was 'well tolerated'. This echoes what Dr. Pierson writes in her article: "most veterinarians have not observed an adverse reaction in their patients". I have personally never seen an adverse reaction to Convenia. Several published studies have reported only mild side effects with the drug (more below). It seems that, on balance, Convenia is a safe drug in the majority of cases (serious effects like those mentioned here are reported in less than 1% of animals receiving the drug). However, this is of no comfort if your cat is one of the minority.

Dr. Pierson has received no doubt hundreds of emails and letters from distraught cat owners who believe their cats have become ill or died due to Convenia injections. A proportion of these must be true, but if we are to make a useful assessment of the information then it pays to be cautious. The article itself states that a post-mortem examination must always be performed to prove that Convenia was the cause.

Because Convenia is an antibiotic, all of the cats to whom it is given (should) be suffering some kind of health condition involving infection. Some of them will be seriously ill. It's a sad fact that some of these cats would display symptoms of illness such as seizures, vomiting or anaemia anyway, and some may even pass away from their disease. It doesn't mean that the Convenia is the cause, even though the timing may fit.

Remember also that many seemingly unexplained deaths in cats are due to subclinical HCM, a heart disease that may cause no symptoms until the cat encounters a stressful event. That stressful event could be a visit to the vet for a minor problem such as a cat bite injury. The cat with undiagnosed HCM may have to wait in a waiting room full of dogs before being examined. Then their temperature is taken and/or the abscess lanced. They are given an injection of Convenia and sent back out into the noisy waiting room to endure a car ride home. Later that day, that cat's poor heart could have reached the point of no return and they collapse. Convenia could get the blame when many other factors were involved. I know this is a sad example, but not one that is as uncommon as we'd like and unfortunately it does happen. 

It's all about looking at things in context, and not focusing on one factor out of many.

Anyway, the big issue with Convenia is clearly the fact that once given, you can't withdraw it. You can stop giving oral medications if the cat has side effects, and at least short-acting injections wear off within a day or so. Once given, Convenia is _marketed_ to stay in the system of the average cat for 14 days. Let's look at the study published by Pfizer (who became Zoetis) in 2006, which looked at how long Convenia stays in the system of cats.










http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2885.2006.00795.x/abstract

Despite being a long-acting injection, Convenia reaches its peak levels in the bloodstream quite quickly after its given: about 2 hours. The 'mean elimination half life' refers to how long it takes for those blood levels to fall to 50% of this peak. In these cats, this took an average of 166 hours - that's seven days. If you're good with maths (which I'm not), you can use these figures to calculate how long the substance stays in the body. The field studies conducted by Pfizer calculated that trace amounts (<3%) of Convenia would still be present in the cat's body after 65 days, which is obviously much longer than the 14 days cited in the dosing instructions.

This sounds scary, and it certainly does pose a problem if a bad reaction to the drug is seen or suspected, but there are a few points that remain unaddressed here:

1. Repeat doses of Convenia every 14 days will lead to accumulation of the drug in the body, since by 14 days not all of the previous dose has been eliminated.

2. 50-75% of every Convenia injection is eliminated from the body through the urine. While this actually makes it a good choice for urinary infections (plenty of the antibiotic accumulates where it's needed), we have to remember that cats with kidney disease may not excrete it as efficiently. Therefore, it could take much longer for those cats to completely get rid of Convenia, and the dose should be adjusted accordingly (this is not unique to Convenia; there are literally dozens of drugs that must be adjusted when they are used in cats with kidney or liver disease). You will notice that the SPCs state that 'the safety of Convenia has not been assessed in animals suffering from severe renal dysfunction', so we currently don't have any official data to known either way whether or not it is safe for use in such patients.

3. Just because Convenia stays in the body for at least 65 days, that doesn't mean it will be effective for 65 days, nor will it necessarily be present in high enough levels to cause any side effects for that long. This is clearly an advantage if the cat isn't tolerating Convenia - I mean, ~65 days sounds alarming, but they won't necessarily be affected for the full 65 days as the levels decrease. However, these low levels are considered 'subtherapeutic', ie they are too low to be effective. This has raised concerns amongst many veterinary professionals about creating antibiotic resistance, as 'weak' bacteria are killed off by the low levels but leave the 'strong' bacteria behind.

4. I don't have access to the full paper, so I haven't seen the exact figures, but I have read in veterinary discussion forums that the calculated duration of 65 days was down to a single cat. While the average 'half-life' of Convenia in the above study was 7 days, there was one cat in which it was reported as 13 days. This single cat pushed the entire figure up, thus making the '65 days' figure longer than it would be in the average cat. I can't comment any further on this, as I haven't got all the information myself, but if it's true then it could mean that Convenia actually hangs around for a much shorter time in the average cat's body than we thought.

5. With regards to the concerns about being unable to withdraw the drug in the event of an anaphylactic reaction, it can be argued that the same applies to vaccinations (one of the most common culprits of anaphylaxis). Once they're in, they're in - and for a lot longer than Convenia.

There are plenty of good things to say about Convenia. Cephalosporins, as a class of antibiotic, are what we call 'time dependent'. This means that they need to stay at a minimum level in the body for a certain length of time. As long as they reach that certain level and stay above it for as long as possible, they'll be effective. If they drop below, it can stop them from working as well. With tablets, there is always a risk of the drug levels dropping if a dose is missed or given late. With Convenia, there is no such danger - which in itself may help ensure the infection is cleared completely and more quickly with less risk of antibiotic resistance developing.

Injectable medications are also considered less likely to cause tummy upsets and affect appetite than oral medications.

And, true to its name, it's terribly convenient. Most cats are not easy to medicate (and remember that we on here are by our very nature the more dedicated cat owners who may be more experienced as well - the 'average' cat owner may feel even less confident about administering oral medications to their cat). Some cats roam, and are not guaranteed to be back in time for their dose. Other owners lead busy lifestyles that make it hard for them to administer regular oral doses. Some people are just lazy. Whatever the reason, a one-off injection is an attractive proposition to cat owners and it is asked for frequently. "I can't give tablets; can't you just give him an injection?" Most people ask for the injection rather than the tablets even though it costs substantially more (Convenia is not a cheap drug), especially if they've had it before. "Last time she just gave an injection, I'd prefer to have that again please." It's not always easy for vets to be sure their feline patients are receiving the medication they've prescribed, and equally difficult to convince some owners that they should at least _try_ to give a tablet before writing it off. It's surprising how many owners come back complaining that the treatment didn't work and blaming the vet, when they didn't even give all the medication prescribed!

It's hard for vets not to reach for Convenia to make life easier for their clients, but they are not faultless in this. Personally I share Dr. Pierson's opinion that Convenia is overused in practice. In 2011, a paper was published in JSAP (the Journal of Small Animal Practice) that found that Convenia was the second most commonly prescribed antibiotic in cats in the UK (after Synulox and its relations), accounting for 15% of all antibiotics given to cats. Cats were 17 times more likely to receive Convenia than dogs, which is probably due to a combination of cost (a Convenia injection for your average Labrador could cost up to £100!) and the fact that dogs are usually easier to medicate than cats. That said, around 13% of dog antibiotic prescriptions were for cephalexin, another cephalosporin in the same class as Convenia only in oral form.
Link to abstract: http://www.ncbi.nlm.nih.gov/pubmed/21824147

Her sections on dentistry and UTIs are spot-on. Antibiotics are very rarely necessary in dental disease (you can use them to treat periodontal disease without doing dental work, and it'll reduce the pain, smell and infection for a while, but it'll all come straight back and you won't have achieved anything tangible; dental disease needs dentistry). When antibiotics are necessary, Convenia is not a good choice to tackle the bacteria you need to. You're better off with something like clindamycin. In a similar vein (though not brought up by Dr. Pierson), it's not the best choice for respiratory infections either. It's not the worst, but something like doxycyline will be much more effective. This is supported by a 2012 paper that found oral Synulox and doxycycline worked better than Convenia at clearing URIs in cats:










http://www.ncbi.nlm.nih.gov/pubmed/22765368

_An aside: I do note that Dr. Pierson suggests that clindamycin and doxycycline in tablet form are contraindicated in the cat, since they can cause inflammation and narrowing of the oesophagus. That's definitely true, especially for doxy, but in the UK the only form of doxycyline we have is tablet form and it's an excellent antibiotic for cats so it's that or nothing unfortunately. They have a liquid form in Australia, I can only hope that'll pop up over here at some point._

As for UTIs, they are not overly common in cats with cystitis symptoms anyway, and antibiotics are usually not needed full stop. Personally I wouldn't consider Convenia an inappropriate antibiotic in genuine feline UTIs, especially since it's licensed for _E.coli_ infections in the cat. But oral medications such as Synulox (amoxicillin-clavulanate) are a more common first choice.

A Pfizer study published in 2008 compared Convenia to oral cephalexin (brand name Rilexine) in treating UTIs in cats. Here's the abstract:









http://www.ncbi.nlm.nih.gov/pubmed/18422501

Cats with bacteria in their urine were randomly selected to be given Convenia or cephalexin (placebo tablets were given to the cats who had Convenia, because the vets and owners involved were blinded to which drug the cats were receiving to avoid bias). Once the unsuitable cats were excluded (for example those with other diseases or who didn't complete the course of tablets), they were left with 82 cats: 54 on Convenia and 28 on cephalexin. The bacteria were cleared in around 3/4 of the cats and the two drugs compared well. However - some cats were withdrawn because _their symptoms didn't improve_. Hmmm... why remove the cats who didn't improve, when you're specifically looking at whether or not they improve? Make of that what you will. Also, six of the cats on Convenia cleared the original bacteria but developed new infections instead. This only happened to one of the cats receiving the other drug.

It's difficult to make accurate assessments in studies with such a small number of patients (human studies involve thousands of cases; in veterinary medicine we have to make our recommendations based on studies involving 82 cats - see the difference?). But it seems safe to conclude that Convenia is definitely not BETTER than oral cephalexin, and may actually be worse. The only reason to use it, unless you culture an infection specifically resistant to everything else, would be if the patient truly cannot be given oral medications for whatever reason.

As for safety, here are the adverse reactions that were witnessed in this study and another similar one comparing Convenia to Synulox in the treatment of skin infections/wounds (also from Pfizer). You can see that the incidence of side effects wasn't all that different between Convenia and the drugs to which it was being compared. Remember also that in both studies some cats were receiving other medications that could also influence side effects.


















Link to the skin infection abstract: http://www.ncbi.nlm.nih.gov/pubmed/17725587

Generally, Convenia appears from studies and in practice to be effective when used for what it's licensed for - skin infections, wounds and abscesses, and some UTIs. It's not quite as effective in the treatment of respiratory infections (though it isn't useless), and is not really indicated in dental disease for all sorts of reasons.

BUT! There are plenty of alternatives, and I have to agree with Dr. Pierson's recommendations to use them wherever possible. Daily injectable antibiotics are an option but can become costly and stressful for both cat and owner if they need to be performed at the veterinary practice each day. We're limited in long-acting antibiotic injections (long-acting amoxicillin gets you 48 hours, but it's not as broad spectrum as the Synulox types (the potentiated amoxicillins) and still carries the same risk of side effects such as GI upset and anaphylaxis). Convenia is pretty unique in that respect, which is what makes it such an attractive option for so many owners and the vets who are caring for their cats. But I think the profession could do more to try and prescribe oral medications before reaching for the Convenia bottle. Most amoxicillin-clavulanate (Synulox et al) tablets are crushable and reasonably palatable, and many cats will take them readily in food without having to go through the trauma of pilling. Synulox is also available in liquid form, as are clindamycin (Zodon, Clindaseptin) and the fluoroquinolones (although of these, Baytril isn't recommended in cats and Veraflox should be reserved as a 'last resort' antibiotic and definitely not used willy-nilly).

Here is the link to the SPCs for Convenia: http://www.noahcompendium.co.uk/Pfi...n_for_injection_for_dogs_and_cats/-43046.html


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## TallulahCat (Dec 31, 2015)

My Mitzi had it a few times because of a combination of her not being particularly handlable, and my own severe allergy to penicillin. Even if I wore gloves she would have shredded them. She never had a bad reaction from it.


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## OrientalSlave (Jan 26, 2012)

Fantastic post @Ceiling Kitty


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## Paddypaws (May 4, 2010)

Huge thanks to @Ceiling Kitty for this post. Convenia has been recommended post op for my Milo and although I have had cats who have been given it before without issue, I do like to do a bit of research before giving the go ahead.


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## chillminx (Nov 22, 2010)

A couple of my current cats have had Convenia injections in the past and have not had any apparent negative side effects.


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## Sacrechat (Feb 27, 2011)

I’ve had cat’s in tha past who were given Convenia without any side effects, however, it failed to clear a UTI in one of my cat’s.


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## Lottiecat (Sep 28, 2010)

Both of my cats have had it and both been fine. My girl had it 17 days ago and really picked up 4 days later


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## buffie (May 31, 2010)

Meeko had it and suffered dire rear for 2 weeks after , but that was preferable to the horrible urinary problems he had before being given it.


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## Forester (Dec 2, 2012)

My semi feral ( impossible to pill ) had convenia without side effects.

My last ( before Dylan ) cat had it following a course of oral antibiotics which had caused a severe reduction in appetite , 3 days after the convenia he stopped eating completely .He was extremely difficult to syringe feed. He was PTS a few days later after GI bleeding. He was 16 years old and had stage 2 kidney disease which was relatively stable. 

Dylan's notes are marked that he is not to be given Convenia. I would happily give it to an otherwise healthy cat who could not be pilled however I would not agree to its use in a cat with a history of inappetence after oral antibiotics.


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## Treaclesmum (Sep 26, 2011)

Jumpy’s had it 4 times and Pixie once, and they have been absolutely fine, it really has been a Godsend for them.


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## Judi Kirkland (Aug 4, 2018)

A friend of mine had a very recent experience involving Convenia.

His 4-year old female cat apparently had a urinary tract infection [UTI]; she was otherwise a healthy cat. The cat was taken to a vet [not her regular vet], who as a first-line approach gave her an injection of Convenia.

Within a couple of hours the cat had become "a zombie"-extremely lethargic and not eating or drinking. The cat's health rapidly deteriorated and two days later she had to be euthanized. The severe reaction was clearly caused by the Convenia injection.

I understand there are many far less risky options to deal with a UTI in a cat, and Convenia appears in any event to be touted primarily for 'skin infections'. Plus Convenia stays in the body for a long time, as opposed to other non-injectable drugs that the body can get rid of quickly.


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## QOTN (Jan 3, 2014)

Judi Kirkland said:


> A friend of mine had a very recent experience involving Convenia.
> 
> His 4-year old female cat apparently had a urinary tract infection [UTI]; she was otherwise a healthy cat. The cat was taken to a vet [not her regular vet], who as a first-line approach gave her an injection of Convenia.
> 
> ...


Please read post number 6 in this thread. You will find out all you need to know about convenia. Most of the rhe rest of us who contributed have had reason to be grateful for the benefits provided by this particular drug.


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