Healthy cat suddenly starts to vomit non stop

[Chenenid]

I took my cat in for a general check up required by the insurance, and after the check up the vet told us that my cat is overweight and needs to be put on a diet. We ended up taking prescribed food home.
Now the vet did tell me to slowly replacing his food with the new food. But the first night I forgot what she said and switched to the new food completely. He ate it, didn't like it very much, left a lot in there, but he was fine.
The next day I remembered what the vet told me, so I decided to go back to do slow convertion. I mixed half can of what he used to eat with the new food. My cat devoured it. But a few hours later he threw up all of his food.
Then the vomit just did not stop. The next morning I got up to find out that there were 6-7 small puddles of vomit everywhere.
Took my cat to another vet (the one we went was fully booked), explained what happened, did bloodwork, and was told that everything seems normal. So we went home with some anti-nausea meds but that was it.
I thought maybe the new diet is causing him throwing up so I switched everything back to what it was.

But since the vomit my cat hasn't really been eating, whereas before he is the one who cannot wait for dinner time. And the next day the vomit did not stop. He is also completely uninterested in any food, even one of his favorite.
Today he is in very low spirit, did not ask for cuddles and vomited huge puddles again.

I honestly don't understand what is going on.

I've been searching online crazy trying to find answers, and the only thing that I feel might be the cause was that we've been feeding him fancy feast for years. I saw online that some people's cats are throwing up on fancy feast and sudden allergies could happen.
Would it be that the new food triggered the allergic reaction?

I'm really hoping some answers and I'm desperate.

 

[hybriseris]

Hi there! I really feel for you.

New food wouldn't trigger a reaction to the old food. Any food over the long term can cause sudden allergies, just like we humans can develop sudden allergies to things we've eaten or products we've used for years, but that doesn't seem likely here.

It's possible your kitty has a very very sensitive stomach. It's usually recommended to change to a new food over the course of a week, introducing only a small amount of the new on the first two days, half and half by the middle of the week, and then full transition by the end. It's possible the new food was just too much too fast, and your kitty's digestive tract is just very upset which can definitely last for days.

I would consult with your original vet again over the phone if possible. This may be something that passes in a few days when your cats stomach calms down but it's good to have oversight and to have your cat seen again. It may also be good to find out if it's possible to use the food you were using, just in reduced quantities for weight loss.

 

[FeebysOwner]

Hi. I tend to think the vet food caused the problem since your cat was not throwing up before he started to eat it - is that correct? And, sometimes what happens is that a cat will associate the food they are eating with throwing up and then they lose all interest in them because they feel it will make them sick again. You can also check the ingredients in the vet food against the Fancy Feast and see what the differences are - it is possible there is something in the vet food that just doesn't agree with him.

Feeby has been on Fancy Feast (pate only) for years now and has had no issues with it. So, while some cats might become allergic to certain ingredients in it, I don't think you can assume that Fancy Feast is going to make all cats sick.

I agree with the above, give it a few days to see if he settles down. Try some simple foods to see if that might get him to start eating again - things like boiled chicken or turkey, low sodium deli meats, maybe even try some canned tuna in water. Then, you can gradually reintroduce his old food to him.

And try to determine how much food you were feeding him before so you can see how much you might be able to gradually reduce it to over time, to get the calorie count down. Whatever you do, don't drastically cut down his food - but rather reduce it very slowly over weeks so that his system has time to adjust to smaller portions.

 

[Chenenid]

Hi. I tend to think the vet food caused the problem since your cat was not throwing up before he started to eat it - is that correct? And, sometimes what happens is that a cat will associate the food they are eating with throwing up and then they lose all interest in them because they feel it will make them sick again. You can also check the ingredients in the vet food against the Fancy Feast and see what the differences are - it is possible there is something in the vet food that just doesn't agree with him.

Feeby has been on Fancy Feast (pate only) for years now and has had no issues with it. So, while some cats might become allergic to certain ingredients in it, I don't think you can assume that Fancy Feast is going to make all cats sick.

I agree with the above, give it a few days to see if he settles down. Try some simple foods to see if that might get him to start eating again - things like boiled chicken or turkey, low sodium deli meats, maybe even try some canned tuna in water. Then, you can gradually reintroduce his old food to him.

And try to determine how much food you were feeding him before so you can see how much you might be able to gradually reduce it to over time, to get the calorie count down. Whatever you do, don't drastically cut down his food - but rather reduce it very slowly over weeks so that his system has time to adjust to smaller portions.

Thanks for the advice.
He never likes boiled fish or chicken, I tried to make home meal once but he doesn't touch it at all.

We tried to give him the anti-nausea med, everytime right after the medication he also throws up so today I'm stopping his meds.

Switched back to fancy feast and iams right the next day but he's not interested. I gave him a soup pouch with actual meat shreds in it, if it was the normal him he'd devoured the whole thing in 10 sec, but this time also uninterested.

I'm going to get some grain-free high-end cans today see if that'll interest him.

The good thing I think, is that he's been drinking water tho. I hope this is a good sign.

 

[FeebysOwner]

We tried to give him the anti-nausea med, everytime right after the medication he also throws up so today I'm stopping his meds.

Metoclopramide can be used as a transdermal gel applied to the skin (most likely the pinnae of the ear) to treat nausea. You might consider asking the vet about this med. I think it might require compounding, but a local pet pharmacy or one on-line such as Wedgewood Pharmacy could do it for you.