At the time this article was first published (2013) Onsior was a fairly new painkiller for pets. The active drug is robenacoxib. Before this drug became available in June 2012, a cat owner had little else to choose from when their cat was in need of drug therapy. You had Metacam, which has proven to be at the least unpredictable and at the worst deadly. Or you had Buprenorphine, a drug 30 times more powerful than morphine and in the opiate family.
THERE ARE MORE PAGES ON PAINKILLERS AFTER THE ARTICLE.
Onsior say
Onsior has a website that tells us more about the drug, which is classified as a NSAID (nonsteroidal anti-inflammatory drugs). It’s similar to Meloxicam and Celebrex used for pain management in people. Their company webpage states:
“Pain delays recovery, impacts negatively on a patient’s well-being, and disturbs the bond with its owner and also the veterinary team.”
Discussion and side-effects
The small, yeast-flavored 6 mg. tablets provide a full 24 hours of pain relief. It’s primary uses are for postoperative pain associated with orthopedic surgery, hysterectomy and castration in cats. Onsior reaches maximum concentration in only 30 minutes via the intestinal tract, and is eliminated from the blood within two to four hours via the biliary route.
Onsior is recommended only for three days. It’s usually given half an hour prior to surgery, then 24 hours later the cat gets a second dose, followed by the final dose 24 hours after the second dose. The drug is sold in a blister-pack holding three pills. The pills are around $3 each. For cats over 13 1/2 pounds, two tablets daily are required.
In a field study, the most commonly reported adverse reactions were surgical site bleeding, infected surgery sites, lethargy, vomiting, and appetite reduction. Onsior should not be used in cats that have a hypersensitivity to robenacoxib or known intolerance to NSAIDs. It also can’t be administered with any other NSAID or with corticosteroids.
The most common side effects are lethargy, vomiting, loss of appetite and increased bleeding time. Clinical studies on cats dosed up to 5 to 10 times the daily dose for 6 weeks to 6 months, reported no deaths and/or encountered clinical side effects resolved upon termination of medication.
Update on side effects as at 2021: The Onsior website says that this drug is safe and efficient for use up to a maximum of three days. The report that the most commonly reported adverse reactions were: surgical site bleeding, infected surgical sites, lethargy and loss of appetite. Other possible side-effects include vomiting, cystitis, haematuria, diarrhoea, hair loss, bruising, excoriation, cardiac arrest, ataxia, weakness. The chart below shows the prevalence of these side effects and a study conducted by the manufacturers of this drug. It is published online on their website.
Lorie Huston DVM – input
Lorie Huston DVM on Ingrid King’s website writes that as a 2011 Onsior had similar problems to Metacam in terms of kidney damage. She says that veterinarians at that time were cautiously optimistic but were fearful of the side effects. At that time Onsior was used more often in Europe than in the US. She also states that there were less side effects for Metacam when used in Europe than in the US. It was unclear as to why. The possibility is that veterinarians in the US use the drug inappropriately compared to that in Europe because they haven’t limited access to the proper educational materials about the drug.
VCA Hospitals – input
A large animal hospital chain, VCA hospitals, say (Rania Gollakner, BS DVM, MPH) that some parents are hypersensitive to robenacoxid and other NSAIDs and if so this drug can have the side effects mentioned above. It should not be used they save for patients who are dehydrated or have renal, heart or liver disease. Should not be administered with any other NSAID or corticosteroid. Pets should be monitored closely when given the drug. The administration of the drug should be stopped immediately if there are any adverse effects.
Chart on prevalence of side effects from Onsior field trial
Elisa’s comment
I read several reviews where Onsior was used to treat arthritis in cats. This confused me, because the drug is marketed for short term use for mild to moderate pain. I don’t know how long-term use would eventually affect a cat. Especially since it takes years for some drug companies to warn the public about negative consequences. NSAIDS are notorious for causing gastrointestinal upset. Hopefully it won’t cause something medical to pop up five or ten years down the road.
Having rescued several injured cats, we’ve used all three drugs for pain management. Although Metacam didn’t cause any side effects, I was on edge after reading up on its negative reviews. Update December 1, 2021: since his article was written by Eliza in 2013 it’s come to my notice that the drug in Metacam, meloxicam, is under an FDA (Food and Drug Administration) warning online. They say in clear terms that repeated use of meloxicam and cats has been linked to acute renal failure and death. It’s been approved for one-time use in cats before surgery to control post-operative pain and inflammation. From my personal experience, I can say that I dislike this painkiller. I gave it to my now deceased male cat who had cancer behind his right eye to relieve pain and I think that it caused kidney damage to my horror. It hastened his death through euthanasia. I still regret approving its use.
Our cat Sealy was on liquid Buprenorphine after his two operations. Since it’s a narcotic, it left him quite drugged. Other than that, he experienced no side effects. He sat in his cage and stared at us, or he ate. It was clear he was on strong medication. Sealy was on the drug for several weeks, and we “weaned” him off of it, being an addictive opiate.
The Onsior was definitely the clear winner, used after spaying. No side effects at all and they drug appeared to do what it claimed it could do-reduce pain. No “zombie cat” from using this drug. It will be the drug of choice, should any of our cats require short term pain medication in the future.
Have any of the readers used Onsior? I’m curious whether it’s been prescribed for long-term use for pain. It would be rather expensive, should a cat need to stay on it for longer than the three-day recommendation.
Elisa
Refs:
- http://www.theuniversityanimalclinic.com/
- http://us.onsior.com/
- Updates by MikeB at Dec 1, 2021
Note: this page was first written in 2013 and upgraded and re-published on Dec 1 2021.
Contact a cat rescue you trust and ask them what they’d recommend for pain. Your kitty would still have to see a vet to get the meds but you could mention whatever drug the rescue tells you to use. I’m so sorry you’re going through this.
The Vet said that once she becomes sick I should have her euthanized. Since last I emailed I have given Magneto onsior twice (the dose is 1 daily) I gave her one at noon on Saturday and again noon Sunday. I am also feeding her, her very favorite wet food to see if it would encourage her to eat. For the last 2 days she has eaten a bit and in fact I was really surprised to take 3 pee clumps out of her litter box this morning and 1 poop (she hadn’t pooped for 4 days and didn’t pee for 2 days). I did not give her an onsior today (Monday). If she was going to have an adverse reaction to Onsior would it be immediate? I’m really beside myself with grief, fear, sorrow. She doesn’t appear to be in pain at least not yet…she isn’t well I know that and she is sleeping a lot but she doesn’t seem to be terribly uncomfortable. I do not want her to be suffering but I do not want her to go until I know she is suffering. The vet didn’t give me anything for her pain when I was there. I called the following day and asked if I could get something (to have on hand) for her if I felt she was in pain. Originally, when the Vet told me she was pretty certain it was advanced mammary cancer, she said that the only way to know for sure would be a biopsy. That is when I came home researched and researched on the internet and concluded and confirmed in my own mind that the vet’s suspicion is right. She said after confirming by biopsy she would not recommend a mastectomy because it is extremely painful and the odds of survival are very low. That is when I decided not to have the biopsy. Magneto stresses and is anxious at the sight of the carrier and further stresses at the vet’s office so I didn’t want to do that to her. In fact I asked the vet, that when the times comes to let her go I did not want to take her to the clinic. I just cannot stand the thought of having her stressed and full of anxiety knowing I would be taking her to be euthanized. l will pay extra for the vet to come to my/her home to have it done. Are there other pain medications. Thank you for your kindness in responding to me. I’m a mess… Heather
My dear, I feel your pain and distress. Don’t misunderstand me but I think the best thing might be to not delay anymore and let her go. Be careful that you don’t hang on too long. I did that once and I regret it. Only from what you say I am not convinced that Onsior is the answer. What if there is an adverse reaction? That means more suffering. These are just my personal thoughts. Only you can decide. What did the vet say about euthanasia? The very best of luck.
My dear sweet cat Magneto has mammary cancer *tumors along the entire mammary glands on her right side, one is substantial and it is open and oozing. She is on an antibiotic Clavaseptin 21 pills- 1 tablet every 24 hours. She is failing and there is no help for her. She is terminal and at a time when it becomes more obvious that she is sick and uncomfortable I will do the most humane thing for her . She is using her litter box less and less, only eating a freckle of food and sleeping a lot. She does not appear to be in pain, but I understand that cats hide their pain. The Vet recommended Onsior. I just gave her one. From everything I’ve read in my research on this drug…it says for 3 days only. The vet has given me 16 pills. How cautious should I be with this. I’m trying to make the time she has left on this earth as comfortable as possible for her. I love her so. My heart is broken.