Dermatology in Veterinary Medicine



Post by Dr. Kris Johnson

Post by Dr. Kris Johnson

Dermatology, as you may know, is the study of the skin and all structures of the skin such as hair and toenails. It’s not the most exciting part of veterinary medicine. We don’t get to play with a lot of shiny new gadgets – usually just our eyes and a microscope…and our noses. Yes, dermatology is smelly, sticky, and often downright gross! And I love it. The number of diseases that can affect the skin is enormous! Not only parasites and other infections, but allergies, cancer, and endocrine diseases play big roles. Auto-immune diseases can affect animals just like people, and often cause serious skin conditions, too. When patients come in with skin conditions, they have sometimes been suffering for a long time, often have seen multiple vets, and the owners are suffering, too. Owners never like to see their beloved pet uncomfortable, and if the pet smells or keeps the owner awake scratching, their relationship suffers. Although I love “solving the mystery” of a pet’s skin condition, I realize these cases can be very, very frustrating. The solution is rarely simple, sometimes expensive, and never quick! The topical treatments can be time-consuming to the owner, the rechecks monotonous, the tests extensive, and the problems are often incurable!

However, with careful work-up by us, and a patient and dedicated owner, these frustrating cases can turn into some of the most rewarding successes I see!


Case 1: Nikki


Nikki and her favorite toy.

Nikki and her favorite toy.

Nikki is a female, spayed, 8 year old Border Collie mix who was brought to our clinic with a complaint of itchy skin for the past 1.5 years (she had been seen by other veterinary clinics for this). Her owner also noted that although they have reduced her food a lot, she has been unable to lose weight. She was, indeed, quite overweight when I saw her! She also had a very rough, dry, thin, and brittle hair coat patched with alopecia and darkened skin from chewing in places. She had complete alopecia (hair loss) and thickened skin on her thighs and under her tail. Her abdomen was greasy with red papules (bumps) and inflammation in areas. In short, she was a mess!

First step is to check for fleas. None were found. But because of the location of her greatest hair loss (thighs and under tail) it was recommended she keep on a good, monthly flea product just in case.

Second step is to check for microscopic skin mites with a simple and quick “skin scraping” test in the affected (alopecic) areas. The material collected is placed on a glass slide and looked at under a microscope. None were found (yea for Nikki!)

Third step is to look for bacteria and yeast using an “impression smear”. This is where a glass slide is pressed onto the affected (greasy and red) areas, stained with special stains, and looked at under a microscope. Aha! Here we found bacteria AND yeast. So we started her on a course of antibiotics AND antifungal oral medications. However, skin infections are rarely the primary problem. There is usually some underlying condition that causes the skin to be more susceptible to these infections.

Fourth step is to try to find this underlying condition. For Nikki, this required a long and careful hypoallergenic food trial (and an accidental “challenge” with a different food, wherein her itching became much worse!), meticulous flea control (also with an accidental lapse that resulted in sudden itching and hot spots!) and blood testing for metabolic problems.

Long story short, Nikki turned out to have at least THREE underlying conditions, each different, and each by themselves could cause serious skin issues, but all together were disastrous! Her owner was very dedicated, and over time we discovered Nikki had a food allergy, and benefits from Science Diet z/d, AND has flea allergies, and benefits from a prescription monthly flea product. Her third problem turned out to be hypothyroidism, a common endocrine disorder of middle aged dogs. Once she was put on thyroid supplements, her coat’s luster and volume returned and she lost 20 pounds! Five months after I first saw Nikki, her owner reports they are stopped on their walks by people who want to pet Nikki because her coat is so shiny and beautiful!! Her owners are so happy, and so is Nikki!


Case 2: Oliver


Oliver is a 6 year old male, neutered, longhaired dachshund. His problems started in 2012 with a small area of thickened, alopecic skin on the outside of his left hind leg. A skin scraping to look for mites was negative. This was first thought to be a “lick granuloma” and treated with topical medication. Ten months later the lesions increased in number and became more swollen and had some discharge, so a deep infection or foreign body were suspected. This is what it looked like then:

Oliver's lesion

Oliver’s lesion

Various rounds of antibiotics were tried, without success. A needle biopsy was taken to look for cancer, and results were consistent with “pyogranulomatous inflammation” but no bacteria were found. Oliver was anesthetized and the area was probed for a foreign body, and deep swabs were taken for bacterial cultures but they came back NEGATIVE!

This was a truly perplexing case! We are now an entire year after the first small lesion appeared and have no answer and no treatment. He is starting to get small lesions around his mouth and eyes also, and is lethargic and feeling sick in addition to his skin lesions. It was time to do a biopsy of these areas. Sometimes done as a last resort because of the cost and need for anesthesia, a skin biopsy is often the BEST way to get to the root of a difficult skin problem.

Oliver’s biopsies came back as consistent with an extremely rare disease of dachshunds called “sterile panniculitis”. Basically his skin reacts like there is a deep bacterial infection with “pyogranulomatous inflammation”, but it is “sterile” – completely free of infection! So the treatment is steroids to stop the inflammation, possibly for the rest of his life. Within days of starting steroids Oliver improved tremendously and over time his skin lesions resolved and we were able to wean him down to a very low dose of steroids. He is a happy, healthy, playful dachshund again!

These are just two of the many interesting skin cases we get to see with our patients. And although these are both dogs, we obviously see a lot of cats with challenging skin conditions, too, and even guinea pigs, rabbits, and rats!!

Skin is the largest organ in a mammal’s body, and is exposed to so many allergens, pathogens, and traumas, it’s amazing it can stay healthy at all! One of our jobs is to keep it that way! With your patience and dedication, we can!