Why is my cat lethargic, not eating, and breathing heavy on Onsior?

Sorry to hear about Mr. President. He may have an adverse effect from the Onsior, but is difficult to tell without knowing all of the previous history. I would expect a cat that is hurt to be less active and eat less, but if this was not a problem prior to the vet visit, then I would seriously question the treatment given. Onsior can cause adverse effects to the stomach and small intestines; which can lead to a lack of appetite, vomiting and gastrointestinal ulcers. I am concerned that the vomit was pink, because this can possibly be due to bleeding. However, bleeding in the stomach is usually seen as black, coffee-ground-like specs, so this is not typical of an ulcer. It's best to take a picture of the vomit (if you still can), so you can show your vet. I would recommend you have him rechecked by your vet within the next day to ensure everything is OK. They can help determine if anything different needs to be done. In the meantime, make sure to give food and water as normal and don't attempt to give any treatments without a veterinarian's direction. I hope that helps and Mr. President gets better soon.

It is very likely that he feels the weather in his bones and cats do suffer from arthritis. If the Onsior was prescribed for him by your vet, you can give it to him. If not, I would definitely wait until tomorrow and call your vet and ask whether you can give it to him. We are not allowed by law to authorize or prescribe medication.

Fortunately Onsior is one of the safest pain killers on the market and a one time double dosage is not likely to affect him. i would still monitor him for vomiting, lack of appetite and bloody stools, i would also recommend skipping the next dose.

Onsior is best given as a whole tablet. Crushing it is not ideal. It will not harm her or cause side effects, it just may not be as efficacious. Have you tried giving the tablet in a Pill Pocket? Typically they will eat the tablet whole that way. ( ) Give her a couple with nothing inside. Make sure she likes and eat is and then hide the tablet in one. I would try that first.

Thanks for using Petco Pet Education Center, formerly Petcoach! Heavy breathing can be a sign of many conditions such as pneumonia, asthma, bronchitis, heart disease, among many other possibilities. While this could be due to some extent to his weight, I think that it is also possible that he has something going on. I recommend that you have Max evaluated by your veterinarian for further assessment and treatment. Likely diagnostics to be performed include thoracic radiographs and bloodwork. Treatment would be dependent on findings. Good luck and have a good day!

This does appear to be a normal reaction to oral medication. Cats really do not like the taste of the medication and tend to drool and hold their mouth open. If this was to happen 20 minutes, or more after you gave the medication, then I'd be concerned that it is an adverse reaction to the medication. In that case, it would be best to contact your veterinarian. If the medication appears to be stressing her out so much that she is having labored breathing, then it may be worthwhile to change the way it is delivered. Your veterinarian can advise more about this. It would be good to take a video of what you are seeing after giving the medication. You can show this to your vet and they can help determine how serious this is. I hope that helps and Sofi gets better soon.

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to hear about Chewy. I would immediately contact the veterinarian that was treating Chewy. This is probably not related to the Onsior but related to whatever he had going on. This sounds like some sort of vestibular problem or a neurologic problem. There are many causes of this so it's important to have your vet follow up with Chewy and re-evaluate her. This would be a very rare and unexpected side effect from Onsior. Please contact your vet immediately. Good luck with Chewy.