I have 4 cats. Natasha, 15, and Stanley, 6, often have foamy vomit. Natasha does have periodic fur balls that can be 3-5 inches long. I have never seen Stanley bring up a fur ball. Natasha throws up almost everday. She is a little cat around 7 lbs. Stan is a large cat around 15 lbs. What may cause their stomach problem?
Thank you. Marlene

