Well my 6 month old female had hives the other day and hers are going away and then coming back. Also my 6 month old male has them now and I have no idea what has caused them. My vet said to give them 50 mg of benadryl and mine weigh in the 40's. I wouldn't think that a collar would irritate her and make her have hives. My female has had hives one other time and I had no idea what she got them from that time either. And I dont think it was their food because they have had it for a month and my female had got the hives before I changed the food.

Well her hives looked like bubble wrap all underneath her skin. She looked like her coat was quilted.....does that make sense? There just little lumps all over from head to toe. I gave her a very small dose of liquid benadryl last night and put her in her crate and a few hours later, I checked and the hives were almost all gone. As I was thinking about it, the only thing different was that I had bought her a beautiful new collar that she kept scratching at. Could she have irritated her skin herself to the point of causing hives all over? Don't know if that's possible but it's the only thing I know of that could have bothered her unless she found some kind of plant in the backyard.

What do his Hives look like.

From reading posts below I guess I can give Benadryl. I just don't know how much to give......I'll call vet tomorrow.