Ischemic Dermatopathy: Crusty Ears in Dogs

How exciting can a crusty earflap be? As it turns out, very (or perhaps I need to get out more).

Being a vet is a dream job, but you do see lots of patients with similar conditions, such as upset tummies or itchiness. As the saying in vet circles go, “Common things are common.”

But this doesn’t mean you can drop your guard and become complacent about reaching a diagnosis. It’s important to keep an open mind — every now and again, a rare condition comes along, masquerading as something more common. Such a case was Freddie, the Jack Russell, who turned out to have a rare condition affecting the ear tips.

A Bad Hair Day

Freddie was having a bad hair day — specifically, a bad hair day on his earflaps. His human brought him to see me because the hair had fallen out on the tips of both normally velvety earflaps.

What I found was the tips of both ears were impressively crusty. Think of the salt crusting the rim of a margarita cocktail glass — you get the picture. Beneath the crusts, the skin was reddened and sore, but, bizarrely, Freddie had no lesions anywhere except the ear tips.

Again, Freddie’s medical history was unremarkable. His human is the sort of responsible person who warms a vet’s heart, attending regularly for vaccination and deworming. Freddie was a typical Jack Russell terrier, rarely ill, and possessed a wiry athleticism. An active dog, he loves to play in woods and chase anything that moves.

So what was causing Freddie’s highly localized hair loss?

A Symptom, Not a Diagnosis

On a physical exam, Freddie was a pocket-rocket picture of good health: muscular, in good condition and his entire coat (except the bald ear tips) was glossy as a seal.

Fred was perhaps itchy (his human wasn’t sure), but that was about it for symptoms. Since she was a little late applying his parasite control, then mange was a possibility, given his love of chasing foxes — but that was about it.

First, I drew up a mental list of possibilities. With the dictum “Common things are common,” it went something like this:

• Fox mange (sarcoptes): This itchy parasite has a liking for ear tips and limbs.
• Atopy: Allergies often show up as itchy faces, paws or ears.
• Ringworm: This parasitic fungus can infect noses, paws or ear tips.
• Sun damage: Repeated sunburn on white ears can cause skin cancer, which in the early stages turns the skin pink and makes it bleed easily. (Freddie had deep brown ears, so this was unlikely).
• Frostbite: When extremities are exposed to extreme cold, the tissue dies off. (This requires recent exposure to freezing temperatures, which we hadn’t had.)
• Seborrhea: This skin condition occurs where too much grease is produced and can result in hair loss.
• Pemphigus: This autoimmune condition causes the body’s tissue to destroy itself. Pemphigus foliaceous has a tendency to attack the ears.
• Leishmaniosis: This infectious condition can mimic pemphigus.

My job as a vet is to come up with answers. Many of the above possibilities were unlikely, and when these were crossed off the list, the main contenders left were fox mange or pemphigus. However, I would expect fox mange to be obviously itchy, which wasn’t the case.

We decided to get Freddie’s treatment for itchy external parasites (sarcoptes) with a liking for earflaps up to date. I started Freddie back on parasite control and added some antibiotic because the ear tips were sore and infected. If the problem didn’t improve, then a skin biopsy would be the next step.

I planned to see Freddie back in a couple of weeks. Unfortunately, it turned out he couldn’t wait that long.

A Turn for the Worse

A week later, Freddie was back. Despite treatment, the ears were worse — a lot worse. Again, it’s only the ear tips that were affected and the rest of his fur was in great condition. Again, he wasn’t especially itchy.

The ears were now the potato chip equivalent of an earflap — so thick with scabs and crusts that they were almost crispy. Clearly something strange was going on, so a skin biopsy it was.

Now, if I were a betting person (which I’m not), I’d have wagered money on Freddie having pemphigus. But he didn’t. Instead, the biopsy result came back as “ischemic dermatopathy.”

“Ischemic” means “lack of blood supply,” and “dermatopathy” means “pathology affecting the skin.” In other words, Freddie had bad skin because of an inadequate blood supply to the area.

Learn about common skin problems in dogs in this video:

Causes

This condition is thought to run in families, and it’s likely Freddie got the genes coding for the condition from his parents. Other than that, no one’s really sure what causes this rare condition.

It’s thought that, in some cases, autoimmune disease or allergy may be involved, but for around 50% of cases, no cause is identified.

A quick bit of reading up later, and Freddie’s treatment involved a hypoallergenic diet, high doses of Vitamin E and a drug (propentofylline) that increases the blood supply to the extremities. He’s also having the crusts regularly soaked in oil to soften them so they peel away more easily.

As to the future, again, no one knows. Some cases respond, others don’t. Worst-case scenario? The ear tip can die off and will need to be surgically removed. Let’s hope Freddie responds so he keeps his lovely chocolate-brown ears that add to his handsome good looks.

This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 15, 2017.