My boyfriend took in a cat I rescued not too long ago. He had her almost a month before taking her in to be fixed. It's been a few weeks since she was fixed and he says that she has been throwing up at least once every two days since the surgery. I told him we would call the vet tomorrow but can anyone shed some light on why this might be happening?
:spew:

Is she on antibiotics from after the surgery? That causes my cat to throw up if she doesn't eat first.

But if it's been a few weeks, it would have gone away by now.

Kidney problems can be another.

Thalia, I don't believe she was on any antibiotics.

I really hope it isn't kidney related :( poor kitty.

Have you switched her food? My mom's cats throw up when my mom tries to buy the cheap stuff. :p

Did this start immediately after the surgery or was she ok for at least a few days? The main reason it may start immediately is pain, was she on any pain meds? It wouldn't need to be intense pain, just a general discomfort. The pain meds themself could cause vomitting. I've also seen some cats go into acute renal failure with some pain meds, but this is too long after for that to be the cause (she would have died within a few days of the failure). There are also many reasons why it would start a day or so later. Things that could go wrong: break in sterility and some infection started (most vets give pre-op antibiotics to prevent this from being a problem), one of her ureters got tied off with the spay and the urine is backing up into the kidney and destroying it, as the uterine stump or tied off vessels heal, they are adhering to other parts and causing pain or blocking urine flow from the kidney to bladder. It may also be coincidence that the vomitting started after she was spayed. It will take a vets exam and maybe other tests to figure out what's going on. Good luck and I hope everything turns out all right.

Michael it may be the food. I'm not sure what Ian is feeding her but I told him to stick with one brand and one flavor for a few days and see if she continues throwing up.

As far as I know she wasn't on any pain meds.

Are you giving her milk? Some cats are allergic to milk and it makes them throw up.
My cat also does it regularly, even when she isn't shedding. She hasn't had surgery or anything.

It might be the food she eats. Some cats have food allergies just like humans do. Also, it might be that the surgery has made her feel less secure. We have an older male and a young female. We have to keep the female away while he's eating, or he gets stressed and eats too fast, and then he throws up because of that.