Every so often, your otherwise fastidious cat will do this alarming and somewhat disgusting thing. She’ll awake from a peaceful nap, rise up on her paws, retch convulsively for a moment or two, and spit up what may appear at first glance to be a damp clump. What the animal has disgorged — in the middle of your kitchen floor or, worse yet, in the middle of your prized Persian rug — is a trichobezoar, a wad of undigested hair that is commonly referred to as a hairball.
Despite the term, disgorged hairballs are not always round. They are often slender and cylindrical, shaped more like a cigar or sausage than a ball. According to Richard Goldstein, DVM, an associate professor of small animal medicine at Cornell University’s College of Veterinary Medicine, a spit-up hairball’s elongated shape is imparted by the narrow food tube (esophagus) in which it develops or through which it passes on its journey from the cat’s stomach to the outside world. However, he notes, a hairball that is not disgorged and remains in the stomach will indeed be round — “like a sponge or a rolled-up sock,” he says.
Regurgitated hairballs are variable in size, usually about an inch long, although they can be as much as five inches in length and an inch thick. The color is mainly that of the cat’s coat, darkened by the color of the animal’s food and various gastric secretions, such as green bile. It will typically have an unpleasant though not revolting odor.
Hazardous Potential. Hairballs are the unsavory byproduct of a normal habit. As your cat grooms herself, she swallows a lot of the dead hair that has come loose. This is because tiny backward-slanted projections (papillae) on the surface of her rough tongue propel the hair down her throat and into her stomach. Unfortunately, Dr. Goldstein explains, the main structural component of the hair — a tough, insoluble protein substance called keratin — is indigestible. Thus, while most of the swallowed hair eventually passes through the animal’s digestive tract and is excreted intact in the feces, some of it remains in the stomach and gradually accumulates into a damp clump — the hairball.
It’s not uncommon, says Dr. Goldstein, for a cat to regurgitate a hairball once every week or two. Aside from inconvenience to the owner, this is nothing to worry about. However, the wad of matted hair can pose a serious health threat it if grows too large to pass through the narrow sphincters leading either from the esophagus to the stomach or from the stomach to the intestinal tract. Also threatening, he notes, is a hairball that manages to pass into the small intestine and become tightly lodged there. “This is uncommon,” he notes, “but it is very serious when it does occur. Without surgical intervention, it can be fatal.”
Relieving the Obstruction. A cat that is lethargic, refuses to eat for more than a day or two or has had repeated episodes of unproductive retching or true vomiting should be examined by a veterinarian without delay, he advises. It’s possible that the frequent hacking has nothing at all to do with hairballs. It may instead be a sign that the animal is vomiting from another cause or that the persistent hacking is a sign of a respiratory ailment, such as asthma, in which case emergency treatment may be necessary.
Diagnosis of intestinal blockage is based on physical examination, bloodwork, X-rays, perhaps ultrasound, and a history of the animal’s pattern of hairball regurgitation. If a blockage is detected, surgery may be required in order to remove the hairball. More often, however, therapy will center on protecting the intestine through several days of clinical care that includes the use of a laxative to move the hairball through the digestive tract.
Although laxatives may be effective in enabling passage of a stubborn hairball, Dr. Goldstein strongly advises owners never to give their cats a laxative without the approval and supervision of a veterinarian. The same applies to commercial diets that claim to be effective in preventing or relieving the obstruction.