Royal Canin Feline Care Nutrition Hairball Gravy Wet Cat Food Pouches 85g x 12 pcs Hairballs occur when hair stays in your cat's stomach without passing through the digestive tract. The majority of the hair travels through the digestive tract with ease, but large amounts of hair can result in hairballs.Hairballs can cause discomfort and soreness through stomach aches and regurgitation, as well as digestive health problems - including the loss of nutrition through regurgitated hairballs.Although more likely to appear in long-haired breeds, hairballs can unfortunately occur for any type of cat.