A cat vomiting transparent liquid with foam may be caused by internal parasite infection, gastrointestinal disease, poisoning, or feline plague. First, you must confirm whether the cat has eaten poisonous food. If it is poisoned, you need to induce vomiting immediately. Rescue, if it is not poisoning and the cat is in poor spirits, loss of appetite, diarrhea, etc., it is best to send it to a pet hospital for examination to confirm the specific cause and then carry out targeted treatment to avoid delaying the condition.