So sorry to hear about Tyson getting hives.He has to be alergic to something like grass or food or a bug bite.Last year Jesse broke out in hives in the evening in the house.Not really bad.Noticed a few raised bumps on her head and back.She could have ate a spider or bug and got an alergic reaction.Gave her the childrens Benadryl and they went away.Minpins are great bug hunters.Hope your Tyson gets better.Thinking positive thoughts for him and you.