Foaming at the mouth in cats may indicate gastrointestinal problems. Cats have sensitive stomachs, and overeating, chronic gastritis, or other gastrointestinal illnesses can cause vomiting, especially in summer when feline gastroenteritis is common. However, if a cat vomits not only white foam but also has accompanying symptoms such as high fever, lethargy, loss of appetite, bloody stools, and runny nose, it may have feline panleukopenia and should be taken to the vet immediately. Foaming at the mouth in cats may also be caused by hairballs. Hairballs can also cause cats to vomit white foam, and the vomit usually contains hair. When cats groom themselves, they ingest shed hair, which their digestive system cannot digest. Over time, this hairballs form in their stomachs, affecting their digestive system and causing vomiting.
