Why would a cat throw up on dry cat food immediately after eating it?

Answer:

It sounds like your cat is completely rejecting its food because it cannot digest or swallow it, either from eating too quickly or too much at a time, which could be down to the food itself.

Many brands of food (particularly dry) are packed with corns and grains. This is cheap carbohydrate filler that the food manufacturers use as its a cheaper source of protein than meat is. Cats are strict carnivores, so can only get their nutrients from meat-based protein, not plant-based protein.

Sadly, it is all this carbohydrate filler is probably the reason your cat is vomiting up undigested pieces immediately after eating. Cats cannot digest such a high level carbohydrate at all; the stomach usually ends up working far harder than it should just to try and break the kibble down (a cat's stomach has evolved to break down raw meat quickly - not to store grain). This doesn't help as many cats will just swallow pieces of kibble whole - they will often not crunch the food. The biscuits will often just sit in the stomach for long periods of time and often get converted into fat (this is one of the main causes of obesity) if the cat does manage to digest it. Yes, even vomiting up food the cat has had for years can happen.

It might be advisable to take him to the vets to make sure there is no underlying problem, and to switch him to a grain-free food. There are many wet foods that are high in meat and grain free, but there are also some dry foods out there with no grain such as Orijen. Look at the Ingredients and stay away from labels such as "grain, corn, wheat gluten, grain/corn by product, by product meal" etc.

Answer: Another explanation could be your cat either has roundworm or tapeworm. It is typical that when a cat throws up its food almost directly after eating it, there is a parasite in its digestive system.

For this, there are available treatments which are best to get prescriptions from a vet.

(One thing -- if your cat is mangy-looking, has dandruff, and is much skinnier than usual but eats more than usual, it is more than likely tapeworm. If not, check it's rectal area and tail and if there are little white worms or dried-up worms about the size of rice grains, it's roundworm).

OR, your cat could just be eating the food too fast.