A cat vomiting white and sticky stuff may be caused by improper diet, gastrointestinal disease, stress reaction, or catching a cold. The cause needs to be determined based on the cat's actual condition, and then targeted treatment can be carried out. If the cat has an improper diet or catches a cold, you can feed the cat some probiotics; if it has gastrointestinal disease or the condition is more serious, it is best to take the cat to a pet hospital for examination and treatment.