By Dr. David Duclos
This week we’re happy to have Dr. David Duclos, owner of Animal Skin and Allergy Clinic in Lynnwood, talk about skin disease in senior dogs. Dr. Duclos and his staff take very good care of Old Dog Haven dogs that are referred to him because of skin and allergy issues, and we feel very fortunate to have him in the Seattle area. We’d also like to thank Animal Skin and Allergy Clinic for being a Platinum Paw Sponsor for the Walk for Old Dogs. We appreciate your support.
Skin disease can affect dogs at any age, but in old dogs it can be grouped into two categories. One is those that have been present for a long time, called chronic skin disease. The other is new skin disease that occur mostly in aging pets.
Chronic Skin Disease
The most common chronic skin disease is allergic skin disease, also referred to as atopic dermatitis. This condition is caused by defects in the skin barrier which allow large foreign substances to penetrate the outer protective layer of the skin.
When substances like pollens from trees, grasses, and weeds, or irritating by-products from house dust mites and skin, hair, and feathers get down to the deeper layers of the skin the immune system cells respond, otherwise known as having an allergic reaction. This results in scratching, licking, biting, rubbing, and chewing because of a constant itch. Other things can happen in an allergic response are skin and ear infections. It is estimated that when dogs have ear infections 95% of the time this is due to an underlying allergy.
What do these allergic dogs look like?
One of the most common symptoms of allergy in dogs is sustained itchiness. Many of them will also have hair loss, along with red, scaly, and crusted skin. With a long standing occurrence of the disease the skin can become thickened and turn black. They will often have a bad odor and may have ear disease.
Treatment involves identifying what they are allergic to and may result in allergen specific immunotherapy (allergy shots). These shots contain extracts of what they are allergic to and will induce an immune response that causes the immune system to self-regulate the allergy internally. Other treatments are aimed at clearing and preventing exposure and infections. For allergic dogs, we use special topical treatments that help to restore a better skin barrier and thus prevent entry into the skin by allergens and infectious agents.
New Skin Disease in Old Dogs
The main new diseases in the old dog that affect the skin reflect an aging immune system that allows new infections to occur because it is impaired. Below are a few examples of conditions that older dogs experience that show up as skin problems.
Demodex mites, a small parasite that lives in the hair follicles, can suddenly affect older dogs. These dogs have hair loss, crusting, and red or black skin. Their skin often bleeds easily. Diagnosis of this disease is made by plucking hair from the affected site and examining it under a microscope.
Hypothyroidism, which is where the thyroid gland is producing a lower level of hormones than normal, causes hair loss, recurring skin infections, and weight gain. Some dogs will be less active and may get tired easily on walks. This disease is diagnosed by blood tests and is treated with thyroid supplements.
Other, rarer diseases, like Cushing’s disease, cancer, or liver disease, can show up with skin signs before the cancer or internal signs are seen. All of these require veterinary examination to confirm a diagnosis and to prescribe treatment.
About Dr. Duclos: Dr. Duclos received his Bachelor of Science degree in biology and chemistry from St. Martin’s College, in Lacey, Washington, and received his professional training at the School of Veterinary Medicine, WSU, and his degree in Veterinary Medicine (Cum Laude) from Washington State University, in Pullman, Washington. After graduation, he was engaged in private clinical practice in Forks, Washington, before going to the University of Pennsylvania, in Philadelphia, for his dermatology residency. After residency, he attained board-certification status, and in 1991, moved back to the Northwest to become the owner of the Animal Skin and Allergy Clinic, near Mill Creek, Washington.
In addition to his duties as a specialist in the dermatology practice, Dr. Duclos has also contributed to the advancement of the specialty of veterinary dermatology by writing many articles, book chapters, and scientific papers on various subjects in the specialty of veterinary dermatology. He also gives continuing education lectures to veterinarians and their staff in the local Northwest region, as well as in other areas of the United States, Canada, and Europe. Dr. Duclos is well known in the veterinary dermatology specialty for his expertise in C02 laser surgery and for his interest in clinical photography. Many veterinary dermatologists use his photographs in their lectures and publications.
Dr. Duclos is also known for his discovery of interdigital follicular cysts as one of the causes of pododermatitis in dogs. He developed a special procedure using the C02 laser, which can cure the cause of this condition in affected dogs. He has published several papers and has given many veterinarians hands-on training in the surgical techniques used in treatment of interdigital follicular cysts in dogs.