Q. We just moved to Arizona to New Jersey. Soon after, our 9-year-old Labrador Retriever-American Pit Bull Terrier got welts all over her body. They seem to come and go. Could it be the heat?
A. The dime- and quarter-sized welts you describe are almost certainly an outbreak of hives, known as urticaria. Most likely they are due to an allergic reaction to either insect bites or stings. Arizona is also known for toxic toads (Bufo frogs) that can cause serious allergic reactions including vomiting and increased heart rate.
Possibly your dog has been exposed to some plant that is causing her outbreaks. Home treatment with Benadryl at a dose of about 1 mg per pound every six to eight hours is safe and appropriate.
However, if the hives keep recurring, there could be an underlying medical problem such as a mast cell tumor. These tumors are usually apparent on the skin, but they can also be internal. Because they release mast cells that cause signs similar to an allergic reaction, you can see intermittent outbreaks of hives.
If you cannot locate a source for your dog’s allergic outbreaks, and they continue, please have her checked out by a veterinarian.