Hairballs are disgusting, especially when you step on one with a bare foot in the dark.

What causes these things? Why do some cats produce them prolifically while others never yak them up? What symptoms does a hairball cause in a cat? And why are there so many myths and fallacies about hairballs?

Hairballs, like everything in medicine, have a fancy name: trichobezoars. Tricho means “hair,” and bezoar means “a clumping of material that is held or cemented together in the gastrointestinal tract.” In other words, hairballs are nothing more than wads of hair that have stuck together to the point that they can’t readily pass through the intestinal tract in a normal fashion. So far, so good. So why all the fallacies?

Let’s start with the biggest one: Hairballs are caused by swallowing hair. In an extremely limited sense, this is true — hairless cats such as Sphynxes rarely get hairballs. (More on that below.) But swallowing hair in and of itself is not what causes hairballs.

All cats groom. And therefore all cats (if they have hair) swallow hair. That hair is supposed to pass through the intestines and into the litter box. Unless your cat is grooming himself to the point of baldness (or continuously grooming every cat in a multiple-cat house), his hairballs aren’t being caused by swallowing too much hair. They’re occurring because the gastrointestinal tract isn’t moving the hair through in a normal fashion.

Most cats who produce hairballs have an underlying gastrointestinal disorder, and some of them may develop more serious symptoms over time. Any cat who regularly produces hairballs should see the vet to discuss this.

Another fallacy is that hairballs are “coughed up.” That is patently untrue. Coughing involves the windpipe and lungs.

Hairballs reside in the stomach and intestines. Hairballs do not cause coughing. They cause vomiting. However, they also sometimes cause dry heaving that resembles coughing.

Cats whose yakking behavior produces hairballs on a regular (or even intermittent) basis can safely be said to have a hairball issue. If your cat is coughing or yakking but never produces anything, it’s more likely that he has feline asthma or some other respiratory issue. This is a different, and potentially serious problem. Don’t assume your cat has a hairball problem if he never brings up hairballs. Go to the vet and get some chest X-rays.

Another fallacy involves vomiting. I often speak with clients whose cats vomit regularly. These clients sometimes assume that hairballs are the source of the problem. This often is untrue. If hairballs frequently come up with the vomit, then the hairballs may be playing a role. But remember that underlying gastrointestinal problems tend to cause hairballs in the first place. Those same gastrointestinal problems, such as infiltrative/inflammatory bowel disease, may cause hairballs. Bottom line: If your cat vomits regularly, don’t write it off as a hairball problem. Ask your vet what else might be causing the symptoms.

Many people assume that long haired cats all suffer from hairballs. Look at all that hair — surely it will clog the pipes. However, have you ever noticed that many long haired cats shed less than short haired ones? This has to do with the way hair gets long in the first place. If a cat’s hair grows to half an inch and then falls out, that cat will have short hair. If it grows to two inches before it falls out it will have long hair. Short-haired cats lose their hair faster than long-haired ones.

There is a counterbalance in this matter. Longer hairs appear more likely to coalesce into hairballs, and this sort of evens things out. But in my experience long-haired cats are not more likely to suffer hairballs than their short-haired compatriots.

Some people believe that hairless cats can’t develop hairballs. This is true as long as they don’t have access to someone else’s hair. I once surgically removed a hairball from a Sphynx. He had a habit of eating his owner’s hair — and she had long hair! The moral of the story: Don’t feed your hair to your cat.

Speaking of surgery, I’m happy to say that it is required only in the most severe cases.

Most hairball problems can be treated with a combination of addressing the underlying gastrointestinal issue (this is the most important thing to do) along with administration of hairball preventatives. Most hairball preventatives are pretty crude: They are merely gastrointestinal lubricants that help grease things up and move the hairballs out into the litter box.

If your cat is coughing, vomiting, regularly producing hairballs, losing weight, or suffering from poor appetite, see the vet. Too many people in my experience delay treatment of serious problems because they believe hairballs are to blame.

Finally, let’s address one last fallacy. Hairballs do not, I repeat, they do not cure pinkeye.

Ren and Stimpy, in the episode, “The Cat That Laid the Golden Hairball,” were simply wrong about that, and hairballs have no economic value whatsoever. That’s a shame, I know.

Got a question for Dr. Barchas? Ask our vet in the comments below and your topic might be featured in an upcoming column.

(Note that if you have an emergency situation, please see your own vet immediately!)