There are many reasons for blue cats to vomit and foam. Owners need to patiently check for symptomatic treatment: 1. The cat is in good spirits. It may be vomiting hair balls or unable to digest, causing foaming. In this case, the owner does not need to worry about feeding chemical. Hair ointment/probiotics can be adjusted; 2. The cat is not active, does not like to exercise, and is vomiting and foaming, which should be caused by disease. At this time, the owner needs to send him to the doctor for examination.