I understand male cats can go in heat but my problem is I always had two cats one is four years old and the other is one. But yesterday they started to fight and the young one is going around meowing like mad, tail sick in the air and the older one is fixed but they always got along. They played and used to lay down together. But now when they see each other war breaks out. Could it be one is in heat. The one year old is not fixed is that the problem