A cat that chews on plastic objects such as grocery bags and bottle caps has most likely developed a condition called pica, which causes unusual cravings for nonfood items, according to WebMD. Pica can develop for many reasons, including gastrointestinal issues and dental disease. "Cats may also chew plastic due to anxiety," says Dr. Amy Pike, DVM, of Veterinary Behavior Consultations in St. Louis, Mo.
Causes of anxiety that may lead a cat to chew on plastic include a lack of enriching activity, social tension with other cats in the household, separation anxiety or fear of thunderstorms. "If the cat is anxious, there is a benefit to the cat -- it is a coping mechanism that may help to diminish anxiety, much like hair twirling or biting your nails," explains Dr. Pike.
Some cats with pica are attracted to other nonfood items besides plastic, including wool fabrics, shoelaces, paper or electrical cords, according to Nicholas H. Dodman, program director of Animal Behavior at Tufts Cummings School of Veterinary Medicine.
Dr. Pike's advice is to consult with a veterinarian first to rule out possible medical problems. According to VetStreet, cat pica can be associated with conditions such as feline leukemia, diabetes, brain tumors and feline immunodeficiency virus. Once medical conditions are ruled out, environmental factors can be considered. "Some cats require more environmental stimulation than others," states Alice Moon-Fanelli, PhD, certified applied animal behaviorist at Tufts Cummings.