As we all know, the cat is a naturally clean animal, and that is why it sits licking itself several times a day.  It cleans itself several times a day.  You will have already realized that this is one of its major daily entertainments to which it dedicates a lot of time.

Well, this habit that is so good for its hygiene can sometimes give it a bad turn.  The rough tongue, owing to the roughness of the taste buds, turns into a brush to pull out dead hair.  The cat's tongue works as a real comb and, passing over its body, pulls out the dead hair.  The majority of this ends up being swallowed and may form hairballs in the stomach.  The cat ingests large quantities of fur that, submitted to the different digestive processes, form more or less large balls.

The ingestion can cause several things: These balls can travel through the intestines without causing problems for the cat, in which case it is found in the feces.  There are times when it does cause an upset in the cat.  Although they are small, in general, they end up being expelled in vomit.  The situation gets complicated when the balls pass through the pylorus and head into the small intestine. 

This can cause vomiting without expelling the hairball.  If they are not too large, they can continue the path through the intestine to be later expelled in the feces, as mentioned before.  The situation is really serious when these balls are too large and remain in the intestines.

When this occurs, it causes a general state of malaise in the animal, which can culminate in the total loss of appetite and intestinal functioning, causing an intestinal block.  In these cases you should go to the veterinarian.  In serious cases, the veterinarian will cause the hairball to progress through the intestines to the anus.  In very serious cases, however, the veterinarian will have to cut the intestinal wall to extract the foreign body: this is, however, a pretty rare intervention.

This situation should be resolved surgically to allow the free passage, because, if not, it will result in the death of the cat.