It’s like the classic laundry pre-treatment ad for ring around the collar: You’ve tried drugging it out, you’ve tried immune-boosting it out, but you’ve still got an insanely itchy dog. What are you doing wrong?
You may be tackling the problem from the inside, with anti-itch medications and antibiotics, instead of from the outside – which, for many dogs, is where the problem really lies.
Many dogs with itchy skin and recurrent bacterial infections have a weakness in their skin known as a "barrier defect."
In normal dogs, the skin's barrier keeps water inside the body and substances like bacteria, yeast and pollens out. In dogs with a barrier defect, those substances "leak" into the deeper layers of the skin. Because the body perceives them as invaders, the immune system revs itself up to destroy them, bringing local inflammation to the area as part of the immune response.
That inflammation causes the itching, redness, and irritation we know as an allergic reaction. Most dogs react to the discomfort by chewing and scratching their skin, which further damages the barrier, allowing more bacteria and yeast to penetrate into the deeper layers of the skin, triggering more irritation, itching, and inflammation.
It gets worse: Dogs can eventually become allergic to the bacteria and yeast themselves, triggering an escalating cycle of infection, itching, chewing and licking that leaves the dogs hairless and in pain, and the owners broke from constant, often fruitless, visits to the veterinarian.
In the past, those skin infections have mostly been treated with antibiotics and steroids, plus or minus anti-fungal medications. In many dogs, that approach helped break the cycle by relieving pain, irritation, and infection, and even reducing itching by eliminating bacteria that were causing an allergic reaction in the dog.
Today, however, growing numbers of canine skin infections are by drug-resistant strains of staph, against which the antibiotics that used to control them are powerless.
Speaking at the recent NAVC Conference in Orlando, Fla., board-certified veterinary dermatologist Dr. Douglas J. DeBoer of the University of Wisconsin School of Veterinary Medicine said, “Over the past 10 years, there has been a substantial increase in the prevalence of antibiotic resistance in canine staphylococcal infections…. Many resistant strains are multidrug resistant, showing resistance to multiple classes of antibiotics, leaving the practitioner with few good options for treatment.”
The good news is that there’s a solution to this problem. The even better news is that it’s not costly, and the side effects are few to none. What is this miracle therapy?
“The new finding here is the effectiveness of topical therapy,” said Dr. DeBoer. “Although we’re used to thinking of topical products as adjunct treatments (used in addition to antibiotics), that thinking has changed, and dermatologists are now advocating that topicals be used instead of antibiotics wherever possible.”
Not only do topical products kill even highly drug-resistant bacteria, he said, but reducing antibiotic use can help reduce the development of even more resistant bacteria.
That’s great for the public health and for clearing up a dog’s skin infections, but what about the itchy skin condition known as canine atopic dermatitis (AD) that’s the real culprit here? Are topical treatments the right approach for a dog with AD?
“Historically, AD was viewed as a disease that began on the ‘inside’ of the individual—the immune system,” Dr. DeBoer said. “More recently, this ‘inside-outside’ view has come into some question, and a different view is evolving.”
Research into AD now suggests that the “leakiness” of the dog’s skin is the initial problem that ultimately leads to changes in immune response and high levels of inflammation.
While there hasn’t been a great deal of research confirming this in dogs specifically, Dr. DeBoer said, “There is no question that the epidermal barrier functions are abnormal in atopic people… In fact, the more the concept of ‘barrier function’ is examined, the more it becomes obvious that barrier function is abnormal in AD, and this is a critical part of the pathogenesis of the disease.”