Convenia Injection Chosen Over Oral Antibiotics

Convenia, the long-acting antibiotic injection that maintains antibiotic levels in a dog or cat’s bloodstream for up to two weeks is the hot topic this week.

Let’s look at another case in which Convenia worked out well.

Fritzi is a Shih Tzu who weighs 20 pounds and has a urinary tract infection. A urinalysis revealed that she had round bacteria, cocci,  in her urine. We began an oral antibiotic that has a wide spectrum of effectiveness for cocci, and simultaneously submitted a sample for a bacterial culture and sensitivity test  to a laboratory.

Five days later we had results and the sensitivity portion of the test showed that the antibiotic we first chose was effective.

We called Fritzi’s owner to inform them of the results and to ask them to pick up additional antibiotics so that we could have a total of three weeks of antimicrobial therapy.

They were happy to hear that the organism was not resistant, but had a comment about the medication Fritzi was already on. “She’s been vomiting intermittently since she started it. Not every time, but at least once a day. We tried it with food and on an empty stomach, but nothing made a difference.”

Vomiting, with or without diarrhea, are sometime complaints with oral antibiotic therapy. Many antibiotics are associated with these problems.

We gave Fritzi’s owners three choices:

  1. One was to stick with the same antibiotic but begin giving yogurt several times daily in an attempt to appease the gastrointestinal (GI) tract with beneficial bacteria. The technique works in about 50% of cases and has the advantage of allowing Fritzi to continue to take the same inexpensive antibiotic. Two more weeks of this antibiotic would cost $21.25.
  2. Option two was to change to a different antibiotic. The next best antibiotic infrequently causes GI upset, but costs more. Two weeks for a Fritzi-sized dog costs $61.40.
  3. Option three was to give Fritzi a Convenia injection. The active ingredient in Convenia, cefovecin sodium, is a cousin to the first antibiotic we started for Fritzi, but injectable forms almost never cause GI upset, so we should have excellent results in treatment without side effects. The cost? $65.00

How to decide?

If cost were the only factor it might be worthwhile to try to use the original antibiotic, recognizing that there is a 50% chance that vomiting might continue, which would lead to a change of medication anyway and loss of the $21.25.

Weighing the other two options becomes what modern parlance would call a no-brainer. Two weeks of pills twice daily versus no pills, for almost the same cost?

And nearly identical effectiveness.

While the final decision is always the client’s choice, most people would choose the Convenia injection, I’m sure.

I know I would for my own pet.

See you tomorrow, Dr. Randolph.


  1. Here’s another Convenia horror story: My kitten, who was a stray, is between 5 and 6 months old. (He’s such a good little guy. Everybody thinks so.) He’s had a few problems, starting with a prolapsed anus, which is why I adopted him in the first place. Once I saw his condition, I had to help him. The veterinarian fixed him right up, no problem. A few weeks later, he was urinating in places other than the litter box. I took him in to the veterinarian, and of course, he had a UTI. The doctor prescribed Clavamox, and the UTI cleared up. But it came back about a month later. More Clavamox (which I forgot to refrigerate one day in the middle of the treatment). When I took him back, he still had some bacteria in his bladder, and the doctor suggested Convenia. She gave him Convenia along with his last FIP vaccine. This was last Friday. By Sunday he was noticeably lethargic and warm, but eating and drinking. I took him back this past Monday. He had a fever of 103, and I told the doctor his tummy seemed a bit swollen, but she couldn’t really tell. She gave him fluids and B vitamins. It didn’t help. I took him back on Tuesday. His temperature was 105 and his belly was still swollen. He’s still there, and so far he’s in a decline. He has become anemic. I don’t really understand everything the doctor tells me, but number relating to his anemia is 21. It was 26 yesterday. She has ordered blood for him, which I hope he will start receiving tomorrow, Friday. Fluid is collecting around his intestines. That’s the reason for the swollen belly. I have been visiting him every day, and he’s very much out of it, but he still purrs quietly. He just wants to sleep. His temperature has dropped a little, 104.5. They’re giving him another antibiotic; I guess because fever indicates infection, but I’m not clear about what the infection is. His kidneys have checked out okay. They’re checking for an autoimmune problem. (He tested negative for Feline Leukemia Virus and Feline Immunodeficiency Virus.) I’m not sure what else I can tell you. What I want to know is, when will we start to see some improvement? I won’t discuss anything less than improvement, so don’t bother giving me any harsh reality lectures, doc. I know he could die. If he’s going to live through this, is it possible for him to show progress before the two week sentence is up? By the way, he hasn’t stopped eating and drinking. And so far he hasn’t vomited. Thanks for your time. I’ll let you know what happens.

    • You should ask your veterinarian to call Pfizer Animal Health and submit an “Adverse Event Report.” Feel free to contact Pfizer Animal Health independently yourself, too, if you’d like, and they will record your observations of your pet. Such cases as yours often require involved workups (diagnostic procedures) as well as long-term supportive therapy until they start to turn around. Laboratory testing is crucial to be able to know all of the organ systems involved in the process. With your baby’s signs, I would also like to see the results of a PCR (Polymerase Chain Reaction) test for feline coronaviruses, specifically Feline Infectious Peritonitis. Thank you for writing and please keep us posted on your pet’s progress. To read more about Convenia, click here. To read about the red blood cell count, click here. To read more about Feline Leukemia Virus, click here. To read more about Feline Immunodeficiency Virus, click here.
      Best wishes, Dr. Randolph.

  2. Yesterday I was charged $421.00 for a 80 mg/ml dose for my dog. Is there anything I can do to stop this doctor from ripping us off ? I was also charged $5,000.00 for my dog’s knee surgery and then again to remove the steel plate because of infection and then another $5,000.00 for the other knee. Please give me some advice. Thank you, Carol Andrews
    P.S. No, my dog is not in good shape, he can hardly walk.

    • Carol, this is a matter for you to discuss with your veterinarian. Is he not available? Is he not approachable? Most veterinarians are happy to discuss problems with unhappy clients. Usually it’s a misunderstanding and can be worked out amicably.
      As for the costly injection, I’m unable to comment, as you’ve not indicated what was administered. That your comment appear on a Convenia page and Convenia’s concentration is 80 mg/ml implies that Convenia was given, but, not knowing the body weight of your dog, I have no way of knowing how much Convenia was administered. Veterrinarians are fee to establish their own fee schedules, and Convenia’s injection fee is usually based on body weight.
      You say you spent $5000 on “knee surgery.” but you didn’t specify what kind of “knee surgery” was performed, or, again, what your dog weighs. Surgery on big dogs costs significantly more than small dogs because of the increased cost of anesthesia, time and supplies for the larger patient. That a plate was involved implies that TPLO surgery might have been performed, and that’s an expensive procedure regardless of where it is done or who does it.
      As for the complication requiring plate removal, it’s just one of the complications that can occur after surgery. A friend of mine had his knee replaced. Two years later he was sitting at his desk when he began to have sudden-onset pain and swelling in the knee. Turns out that bacteria from his eczema (a skin condition) had invaded his bloodstream. When the bacteria found the most susceptible tissues in the body, the site of his knee surgery, they made a home and a tremendous complication. The knee implants had to be removed surgically, the infection cleared, then new implants surgically placed.
      It is sad when patients don’t heal as we expect them to, but it is still a fact of the practice of medicine.
      Carol, you asked for advice, and the only advice I can offer is to ask you to visit with your veterinarian and let him know what your grievances are. I hope you will and I hope you will let me know the outcome of your visit.

  3. I AM being proactive. I took her to ANOTHER doctor. She has seen two doctors in less than 7 days. Let’s say the Convenia IS the cause of her deterioration – tell me what the treatment would be to counteract this long acting antibiotic? There isnt one, is there?

    • Dear Almost Home, I know you’re frustrated, please don’t take your frustration out on me. I’m only trying to help you and help your dog in trouble. I recognize that you have seen two veterinarians in seven days, BUT, what your pet needs now is evaluation for a NEW problem that didn’t exist then. No, there is no antidote or specific anti-Convenia therapy, no chelation that will take it out of her body, but there IS what I mentioned earlier: SUPPORTIVE THERAPY. In order for her supportive therapy to be effective, though, your pet’s doctor needs to know what organ systems are being affected, and how they are being affected. That is determined by the testing I’ve recommended, which constitutes a minimum database. With the problems you’ve described with the rear legs, she may need to see a neurologist. No one knows what the outcome of her case will be, but we do know that she has a much better chance of full recovery as we obtain more information and she has maximum supportive therapy. Thank you for your reply, Dr. Randolph.

  4. My dog was not ill. It turns out that she was experiencing a prolonged case of reverse sneeze, which I didn’t know anything about at the time and thought was serious due to the fact that it looks like your pet can’t breathe. Apparently small dogs experience this frequently and it is not life-threatening.
    The second veterinarian I took her to did a thorough exam and could find nothing other than the Convenia that could be causing my dog’s symptoms, which, as of this morning, now include weakness in her hind legs! Her legs appear to either lock out or grow weak and slip around. My dog NEVER experienced this prior to one week ago, when she was given the injection. She continues to look extremely sick, especially in her eyes. I KNOW that this is not normal. I am afraid of what tomorrow will bring. I’m sick at the thought that I’m watching her deteriorate day by day. Am I going to lose my dog over something that she never needed in the first place and should never have gotten?
    I plan on calling the original veterinarian to report this in the morning. And then I will report it myself. It’s scary to think that an animal could have a deadly reaction to an antibiotic that continues to harm them for at least 14 days and there is no way to counteract it. I pray that tomorrow brings no new symptoms.

    • Dear Almost Home, While I’m happy to hear that you are following through on the reporting process, that was only one of my recommendations. You ask, Am I going to lose my dog over something that she never needed in the first place and should never have gotten? The answer is that, without a proper diagnosis and treatment, you are much more likely to lose her than if you are proactive. While it is possible that she may get well on her own, do you want to take that chance? I, too, believe in the power of prayer. However, I believe God gave us doctors for a reason, and that reason is to call on them when they’re needed. Right now, your dog needs a doctor, as evidenced by the fact that her symptoms are advancing, not improving. I thank you for your prompt reply and I look forward to updates on her situation. I’m praying for her, too, Dr. Randolph.

  5. My dog was given a Convenia shot without explaining to me what the possible side effects were or giving me an option of an oral antibiotic. She was given this injection for kennel cough that she does not have (I took her to a second veterinarian as the first did not do a thorough exam and did not listen to me when I tried to explain her symptoms, so I wanted a second opinion). We are on day 7 and my dog grows more and more lethargic. Her eyes are zombie-like and she is not herself. Pet owners KNOW what their pets are like normally, the brightness that usually exists in their eyes. My dog is limp and lifeless and her personality has changed completely. She doesn’t want to be touched when she used to love sitting on laps and petted.
    We have at least 7 more days of this to work through (though, I suspect it will take longer, if she improves at all). I am distraught thinking that she is suffering so unnecessarily as she never needed an antibiotic, let alone such a powerful one! This is just terrible. I am so upset and angry.

    • Dear Almost Home, I feel your pain. Your baby is ill and you want her well. One of the most important things NOT to do at this point is participate in tunnel vision. While you believe that Convenia is at fault, remember that you took her to the doctor in the first place because she was ill. Step One is to have the first veterinarian report an Adverse Event to Pfizer Animal Health. You may make a separate report, if you’d like. Second, or, better yet, simultaneously, take her to a veterinarian you trust and have her examined and sufficient procedures performed to determine the cause of her lethargy, the effects on her body and the necessary treatment. This may include Complete Blood Count, Chemistry Profile, Urinalysis and Chest X-ray. the bottom line is that you want your dog to feel better and to survive this event. Proper treatment depends on an accurate diagnosis and supportive therapy to get through the event, no matter the cause. This is a topic I am extremely interested in and I would greatly appreciate an update as soon as you know more. Best wishes, Dr. Randolph.

    • AlmostHome–I see that you wrote this almost 7 years ago. A month ago my dog received a shot of Convenia and Cerenia (without my consent) and the next day she was completely ataxic. She was rushed the the emergency animal hospital where they tried to tell me she injured her back legs. I kept arguing with them that there was no way that had happened because she was with me the entire time. After having a seizure while awaiting discharge, they finally admitted her and took my claim seriously. The next day she was moved to her regular vet where she stayed for two days being treated with IV fluids and steroids. She was sent home showing “little progress” and continued to stay on steroids. She began making progress and within 3 days it was like a miracle had happened. When I brought her back to the vet they couldn’t believe that she was OK and were surprised. We began weaning her off of the steroids and when it came time to skip a day, she was set back beginning to have problems walking again and she didn’t want to be touched–almost as though it was painful. Her vet put her back on the steroids and a pain reliever. We now four weeks since she has had the Convenia and Cerenia injections (which both claim adverse side effects consisting of neurological and ataxia). She is scheduled to see a neurologist on Monday, but to be honest I am so scared that the effects are not reversible. The timing is terrible as I am 8 months pregnant and now more than $2,000 deep in vet bills trying to save my baby. Please let me know if your dog recovered and what treatments were used. I am desperate for answers, but through research seem to come up empty. I initiated the report with Zoetis, but they have been no help in releasing information on the adverse effects). Any help is appreciated.

  6. I think this killed my cat. She was at the veterinarian for vomiting and dehydration so she was given fluids and IV antibiotics. When she was stable and hydrated she was alert and purring and ready to try it at home. Just before we took her home, the veterinarian administered this two-week antibiotic. Within an hour at home she couldn’t breathe and had gasping breaths. Despite returning to the veterinarian and receiving oxygen, she couldn’t recover because the drug was still being absorbed. She had to be intubated and eventually we had to let her go since she could no longer breathe for herself. It was traumatic to watch her struggle to live and not be able to do anything about it. It just seems like she was recovering until they gave her that antibiotic. I would advise against it and just give oral meds because it’s not worth the risk.

    • MJ, please accept our sympathy for the loss of your kitty. If you are a regular reader you know that our family has recently lost our Pearl and our Martha, so we are right there in the boat you are rowing. One of the most important factors to consider when an ill pet dies is that she was sick in the first place. Something made her ill, or she wouldn’t have needed medication. Certainly it is possible that she had a reaction to the Convenia. Any medication can cause a reaction. Usually patients respond to the kind of aggressive treatment you describe being administered to support her and reverse the reaction. To lose a patient under those circumstances is fairly unusual. Still, there are many other factors that could have caused her death, and only a detailed (and expensive) necropsy would have given you the answer to the cause of her death. In Sympathy, Dr. Randolph.

  7. My 2-year-old cat had a URI that was not clearing up after 2 weeks and sneezing violently. He received a shot of Convenia on 7/14/11 against my better judgment, I was concerned about it being on board for so long if he had any adverse reaction, but the veterinarian said if anything happened “we can give him steroids.” He lay around like a limp rag for a week and was drinking water voraciously. I took him to a different veterinarian who did lab work and his creatinine is elevated at 2.6. He said he “doesn’t know if it’s related to Convenia or not.” He was given some subcutaneous fluids. His urine specific gravity was normal. He received the shot 16 days ago and still is not himself. He was a non-stop active 2-year-old, and now he moves around like he is 15. I wish to God I’d never let him receive that shot.

    • It’s a sad fact of the practice of medicine that sometimes bad events will occur despite the best efforts of the doctor, patient and pet owner. Sometimes there are factors in a patient’s illness that cause problems and are actually not medication-related at all. Major pharmaceutical companies, such as Pfizer, have departments to investigate unexpected events such as this. Please ask your pet’s doctors to report this to Pfizer Animal Health for further investigation.

  8. Hi. Two of my cats have also had Convenia injections. Both were for wounds that abscessed (they’re very pampered barn cats … up to date on all vaccinations, spayed, neutered, etc. but, they roam and get into things, lol) The Convenia worked fabulously well for both cats. My only complaint is the cost! I’ve spent $400 in vet visits in the past three months for abscesses antibiotics for these two … the shot is like $45 then there’s the office visit, and the antiinflammatory injection. I wish I could just keep it on hand, lol.

  9. Two of my cats have had Convenia injections. Psycho has had it twice. In fact she had one about an hour ago. The other was in November of 2010. Psycho had no problems at all with it. Isis had it 7 days ago for a respiratory issue. Cleared her up in a couple of days. Had no problems with the Convenia at all at any time.

  10. Two different veterinarians have used Convenia on two different cats of mine. One cat , Missy, was very sick with an upper respiratory tract infection (coughing up mucus) and also suffered from stomatitis. She was given the Convenia shot and that put her on the road to health. The second kitty, Sage, was given a Convenia shot Friday and so far she’s doing great. No problems. And I expect she will recover from her bacterial infection shortly. When you have semi-feral or very uncooperative kitties, it’s wonderful to have a long-acting injection like that.

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