[anonymous]

“Anon, One of the stories on the link you sent me said they gave their dog Zyrtec. I would if it worked. I was told human allergy rx has not been a proven remedy for dogs.”

A veterinarian that has examined and diagnosed the dog can order a medication for “off label” use. In general, it is not intended for veterinary use.
Just as he would recommend a shampoo specific to your dogs condition.