For no reason other than the odd symmetry of it, let’s follow last week’s column (why dogs eat weird stuff) with this: Why cats vomit so often. I share my home with three cats and I’ve come to rely on Persian-style carpets for masking the telltale stains of hairballs (although going barefoot before that first cup of coffee can be risky). Yep, cats hurl frequently. But why?

The spit-covered cylindrical glob of hair mixed with food which arrives after some ack-ack-acking and a spasmodic lurch or two is, technically, a trichobezoar. Yucky, sure, but actually the result of a good, clean habit. As Fluffy grooms herself, special structures on her tongue (papillae) comb loose hair into the back of her throat and down her stomach. Most passes out the back end but some remains. This collects over time into a hairball which, eventually, gets to see the light of day.

That “eventually” is important. One hairball every week or so is common. However, retching which does not produce a hairball, especially if accompanied with symptoms like lethargy or disinterest in food, can mean the hairball is headed the wrong direction: into the digestive track where blockage can result, or it can indicate some other potentially serious problem. So ack-acking without a hairball means a trip to the veterinarian is in order.

Reduce hairballs and help your cat’s self-grooming with frequent (daily if possible) brushings and combings. This removes the most of those loose hairs before your cat gets the chance to ingest them. Over-the-counter “hairball remedies,” ideally with your doctor’s prior agreement to their use, can also go a long way in preventing this hairy hurling.

By the way, housecats are not the only animals who produce hairballs. Ripley’s Believe It Or Not brags of a collection of more than 600, the largest coming from a cow. A tiger’s basketball-size hairball is a recent addition. Tell Fluffy she has a long way to go.

Ken White is the president of the Peninsula Humane Society & SPCA.