I have a 13 year old siamese (possibly balinese) cat. They eat dry food during the day and at night they are used to betting a 1/2 can each of wet food as a treat. Recently, my husband switched from wet pouch type food to a well known brand of canned food. Before the cat is finised eating even his 1/2 of the can, he vomits all of it. He does not vomit the dry food or anything else. Could this be due to the change of food?