Seems we have a toxic Italian Greyhound – help!?

and we need some clues. The vet he is at hasn’t any idea. Here is the skinny:

We had Roman for about 2 1/2 weeks – he was to be our new pup. [I have 1 other Iggy and 2 cats]. Zak has selective animal allergies but had no issues for well over a week after we brought Roman home. Suddenly Zak got a URI and one day broke out in hives after hugging Roman. Weird. Roman ate what Reno [my other Iggy] does [Purina One with Nutra wet mix], ran around with Reno – did what my other does. Zak had NO issues at all, then all of a sudden major issues with breathing and the hive thing.. So off Roman goes to his new home…SHE also developed breathing issues and hives within a day of having him. She has NO animal allergies. Off Roman goes again [poor Memo, at this point he is not a happy puppy] – within an hour she ALSO has breathing issues. She fosters Iggy’s and has NO animal allergies and was the one who orignally took him in to get him to his first foster home and had NO issues then. Now the vet where he is now [our Rescue Vet] says he has sarcoptic Mange – yeah no. My animals would have that by now if that was the case, they don’t and doggie scabies do not produce hives. Here is the thing I think is an issue but don’t know: Roman loves baby carrots. He eats them like most dogs eat milk bones. I am wondering if those may be the issue? Like, they absorbed pesticides [I washed them] and when Roman ate them, it didn’t affect him but some how he is leeching the toxins out his pores? That is the only thing any of us who have come in contact with him can think. Could this be? Anyone have any ideas? I am at my wits end. Since this all started at my house, I do not know anything besides the carrots that could cause this. He got into NO cleaners, it wasn’t his shampoo, he ate nothing weird in the yard [he was watched when he went in the back - pool area], he didn’t roll in the grass [but I have organic lawn service so that's not it], he didn’t get ahold of anything bizarre in the house – ugh! I am at my wits end – help
Kaitlyn and Becky – thank you! I will get with the IGCA rescue and see about a specialist and if we have one. I agree – poor baby is miserable right now being boarded at the vets : ( He has NO clue why he has been bounced 3 times in 4 days and my cats miss him oddly enough not to mention my other Iggy. I miss him most of all – he was my boy [Reno likes the hubs best *lol*]. I too think it is something chemical with him but the other vet dismissed this out of hand }:-<

Poor pup. I’m guessing he’s got something unusual going on with his chemical make-up, something out of the ordinary for his breed and dogs in general, that humans are sensitive to. Maybe his pH/alkalinity is out of whack? Maybe the oils in his skin or his saliva chemistry are ‘off’…maybe an overabundance of bacteria, yeast, etc ?
I think you’re better off asking an allergist/physician rather than a vet on this one…but I do agree that mange mites is very unlikely — and of course it’s easy enough to prove/cure it that were the case.