Two weeks ago, I took Dozer to the regular vet to treat staph lesions that were popping up here and there. The weekly baths and occasional Zyrtec just weren't cutting it. The vet prescribed a standard round of prednisone (to stop the itch) and cephalexin (to stop the staph).
Today, as soon as I saw the telltale pinpricks of oncoming urticarial vasculitis, ("super hives") I called the dermatology/allergy vet. (Well, first I screamed "NOOOOOOOOOOOOoooooooooooo!!!" and then I called the vet.)
|What urticarial vasculitis looks like in the first few hours.|
Ironically, today, after I reviewed some historical blog posts about Dozer's hives (like this one in 2009, this one in 2010 and this one earlier this year), I saw that he'd been taking cephalexin, an antibiotic, in every case.
Why wasn't the allergy deduced years ago? Because the hives never happened at the beginning of a cephalexin course—only at or near the end. Dozer could go two weeks on cephalexin and completely finish the course without a reaction, only to break out in hives a few days later, while taking no medications at all.
This mystery was also solved today, because the derm vet noted that Dozer usually gets prednisone or a cortisone shot at the same time that he's given the cephalexin. Although the point of the steroid is to cut down the itching from the staph, these steroids stop all allergic reactions. Period. Including the reaction to the cephalexin. After the short steroid course tapers down, there's nothing stopping the hives anymore. Thus the delayed reaction.
|Six hours later--not looking too bad this time!|
|Sleeping soundly... with his face inches from the space heater.|
First thing tomorrow morning, I'm calling the regular vet to ask them to flag this allergy in his file. No more cephalexin!!