By John Andersen, DVM
By far the most common problem that I see as a veterinarian is allergic skin disease in dogs. Ear infections, rashes, hair loss, itching, and foot chewing—these are all common manifestations of allergies in dogs.
In humans, allergies are also a very common problem. I am pretty confident that you probably know a few people close to you who suffer from allergies. With humans, we tend to see sneezing, runny nose, congestion, sinus infections, itchy eyes, and asthma. Not to mention the rise in food allergies. It seems to be an ever-more allergic world in which we live. Or perhaps we are all just becoming more and more sensitive to it. Or maybe it’s a little of both.
Interestingly, we don’t often see dogs coming in with sneezing and congestion from allergies. In fact, this is pretty uncommon, even when the exposure is through their nose/respiratory tract. Dogs tend to have their histamine release from allergy exposure in their skin. This causes the skin (including ears) to become itchy and inflamed. If mild, you may just see your dog itching or licking a bit more than he used to. Chewing on the feet is a common sign of this allergic itch.
Now, ramp up the allergic inflammation a notch or two, and the skin starts to change a bit. Not only is it itchy, but now the allergic inflammation creates a change in the microenvironment of the skin. The skin surface is now warmer, there is more oil production, and there is often more dandruff and shedding.
This is important because dogs’ skin, like our own, is completely covered in microorganisms, mainly bacteria and yeast. Normally, these yeast and bacteria live in a perfect balance—we don’t even know they are there because our skin keeps them in check. However with allergic inflammation, that microenvironment upon which they live is now changed, and they love it. Bacteria and yeast start to overgrow and go from peaceful cohabitants to a rebellious uprising. Now your dog has a bacterial and/or yeast infection.
The most common occurrence of this is yeast infections in their ears. Please note: it is exceedingly rare for dogs to have ear mites. In 14 years, I’ve seen ear mites a handful of times, compared to thousands upon thousands of yeast infections.
The signs of this are quite obvious—itching and scratching of the ear and shaking the head a bit more than normal. If you take a brief second and simply lift up the earflap, the ear canals should look pale pink and particularly clean. But yeast infection ears have a characteristic brown/black waxy discharge, as well as some redness and sometimes thickening. If you see this discharge in your dog’s ears, your dog has a yeast infection and you should contact your vet for some treatment (typically very easy to eradicate with some drops and cleaning).
Just as common are skin infections. Scabs and hair loss along the back. Rashes in the groin and armpit areas. Red, raw skin between the toes and paw pads. A “yeasty” odor and a greasy coat. Relentless itching. These are all the typical symptoms we see of allergic skin disease in dogs, due to overgrowths of bacteria and/or yeast on the skin.
Although allergies are very easy to spot and diagnose, they are increasingly difficult to understand, and often difficult and frustrating to treat.
My dog Boone has significant skin allergies. He is now a six-year-old yellow Labrador, a classic breed for allergies (although some breeds are more predisposed than others, we see allergies in all breeds and mixes of dogs). When he was about two years old, we noticed he was starting to lick and chew on his feet. We weren’t sure at first if he was just bored or neurotic, because he is definitely a “licker.” Over time, the licking continued and eventually I started to see some moist skin between his toes. Around this same time, he got his first ear infection. I’m a veterinarian, so I regularly take a look in his ears, and I recall one day lifting one up and being horrified to see all the redness and black discharge. I swear he wasn’t even shaking his head one bit! We treated his ears and started bathing him a bit more to deal with his feet.
Over time, I have changed his diet, used special shampoos, used topical medications, and event steroids and antibiotics to continue to put out these secondary infections that would pop up on his feet and then his chin. He would respond to the medications, but then once off them, the itching and skin lesions would slowly start coming back.
We have definitely learned to live with a certain amount of itching and licking. There is a balance there—no chewing would require being on medications 100 percent of the time, which won’t be good for his long-term health. However, never using medications would mean that his skin would continue to get worse and worse, becoming so damaged at some point that certain areas would be chronically infected beyond repair. So I have tried my best to ride the line between these two states.
More recently, I have felt like I have been losing this battle, so I finally did some allergy testing on him. This is a pretty easy test now (but expensive), where we draw blood and send it to a special lab that tests for some regional allergens. To no surprise, Boone’s main allergies were all to grasses.
So now he is currently receiving allergy shots, which are pretty easy to administer. The purpose here is to give very small amounts of the offending allergens to him over time, hoping to teach his body to develop a tolerance to these things. Allergy shots tend to work in about 75-80 percent of my patients who go for them and ultimately allow us to use less medication over time.
Allergic skin disease in dogs can be frustrating, but with a good partnership between you and your veterinarian, most dogs can be well managed and live a full life, with plenty of romps in the grass.