One of our technicians brought in her unhappy kitty named Gizmo last week. Gizzie had been pawing and scratching his chin raw. Beyond the common chin acne some cats can get, this feline patient sported an abundance of bleeding pustules beyond the pallor of the standard blackheads and pimples we often see secondary to ingrown hairs (all that chin rubbing sometimes takes its toll).

Though not quite akin to the adolescent acne humans often suffer through, cats can still manage a passing imitation of a pimply-chinned teenager—at all life stages.

Sometimes it’s the result of sensitivity to plastic food bowls—but more commonly it’s from rubbing their chins along every surface that makes itself available to convey their pheromonic presence.

And then there are cats like Gizmo, whose level of inflammation on their chins and other parts rivals that of any seriously afflicted human adolescent’s—and in many cases looks much worse.

Though these occur most typically on chins, lips and noses, they can also occur anywhere on their skin in crusty, reddish, plaque-like lesions. Alternatively, they can look like chronically ulcerated spots. The latter variety can look so angry and ugly they’re commonly mistaken for bite wounds—until they fail to go away, even after weeks of antibiotic therapy.

Here's one variety we call a "rodent ulcer":

Here's a plaque on a paw:

And yet another on a nose:

One lowly bit of equipment, however, can lay all doubts to rest: the handy microscope slide. In this simple test, the plaque, crust or ulcer is smeared with the slide to rub cells off its surface. The slide is then stained and the cells are viewed under the microscope.

Nine out of ten times, feline lesions that look this nasty will shed cells that look like bursting raspberries: eosinophils, they’re called. Here's a pic:

Eosinophils are white blood cells that occur naturally in the blood in tiny percentages. More often implicated in allergic reactions, they aren’t commonly seen in most wounds when subjected to the impression smear test described above. Hence, when we do see these cells we know we’ve got a very characteristic condition on our hands: the eosinophilic granuloma complex.

Veterinary dermatologists will tell you that these lesions obnoxiously defy reason. We don’t understand why some cats get them and others don’t. We don’t know how to make them go away once and for all (though they do respond amazingly well to the strong immunosuppressive action of corticosteroids like prednisone). And we have no idea what brings them on, though stress seems to play a role in these cats’ eosinophilic flare-ups. 

Gizmo’s impression smear confirmed his diagnosis: an eosinophilic plaque leading to deep furunculosis, a kind of skin infection with nasty draining tracts of pus. A week of prednisone and one shot of Convenia (a one-dose antibiotic) later, the wound is barely there.

It’s kind of amazing, actually, that a sore so serious could have received the heave-ho so quickly. Nonetheless, it’s likely to return. And then Gizmo’s owner will have to decide: How many shots and pills will she have to give over his lifetime to keep his chin happy?

I wish there was a better way. But when it comes to eosinophilic plaques and ulcers it always seems to come down to the complex calculus of steroid side-effects versus basic comfort. Maybe one day we'll look back and marvel at our medical stupidity when it comes to treating these lesions. In the meantime, steroids and antibiotics it is...