Hairballs--cat owners recognize them as cylindrical masses of firmly-packed wet fur found around the house, with what seems to be a proclivity for hard to clean surfaces. Hairballs occur when cats groom themselves and swallow fur. Normally, the fur will pass through the cat’s gastrointestinal system and out in the stool when a cat defecates. Occasionally, the fur stays in the stomach, then is “coughed up” (vomited) as hairball, rather than passing from the stomach into the intestines. Very rarely, the fur can get so clumped up in the stomach that it can cause a blockage which has to be removed either endoscopically or surgically. The best way to prevent hairballs is by regularly combing or brushing your cat to remove loose fur before it can be ingested. Hairball remedies are also available that lubricate and help hairballs more easily pass through a cat’s gastrointestinal system. If your cat is frequently vomiting hairballs even after instituting a regular grooming program and use of hairball remedies, there may be another cause for the vomiting. More than just occasional vomiting of hairballs merits taking your cat in for a veterinary visit.