Whenever Russell Hartstein's psoriasis flares up, count on his 6-year-old German shepherd, Koa, to try to lick the dry patches on his elbows.
“He always seems attuned and curious about people, is very affectionate and observant,” says Hartstein, who is tuned into such things himself as a certified dog trainer.
Harstein has had psoriasis since childhood. Koa isn't his first dog to lick, smell, and stare at skin patches with “what seemed like curiosity and interest.”
People with psoriasis will tell you that Koa is not a rare breed. It's not uncommon for dogs to react strongly to psoriasis flare-ups in their human families.
But why? What is it about psoriasis that draws some dogs' attention?
Experts aren't sure. Some think dogs, with their keen sense of smell, are drawn to a unique odor coming from psoriasis patches. Others believe dogs like to lick that area as a healing gesture.
This Canine Attention Isn't Always Welcome
It can be hard to turn away a friendly dog's licks. But if you have psoriasis, and especially if you get sores during flare-ups, that's the safe thing to do.
“Dogs and cats have a lot of [germs] in their mouths, so any amount licking could lead to ... infection,” says Deborah Silverstein, DVM, a professor of emergency and critical care at the University of Pennsylvania School of Veterinary Medicine in Philadelphia.
What about your dog's health? If you haven't put medication on your skin, your dog should be fine if he or she licks psoriasis patches.
But the ingredients in some psoriasis ointments and creams can cause kidney damage and other serious health problems in dogs if they lick up enough medication, Silverstein says.
Other Conditions Dogs Notice
It's not just psoriasis. Some research shows dogs may be drawn to, or even predict, symptoms of other conditions, including:
- Low blood sugar in people with diabetes
- Melanoma and other kinds of cancer
But this isn't for sure. More research is needed.
“Part of the challenge is that we don't know exactly what dogs are picking up on” when they react to human medical conditions, says Evan MacLean, PhD, director of the Arizona Canine Cognition Center at the University of Arizona in Tucson.
One possibility is that the changes in your body caused by psoriasis, skin cancer, etc. trigger a unique scent that you can't sense but your dog can.
Dogs mainly experience the world through their sense of smell. That “gives them a different perspective and a unique ability to notice changes ... too subtle for us to recognize,” says Melissa Singletary, DVM, PhD, assistant director of the Canine Performance Sciences program at Auburn University's College of Veterinary Medicine in Alabama.
Dogs also can be quick to spot and react to subtle changes in your behavior or physical appearance when you deal with a flare-up of a medical condition, Singletary says.
What about pairing a person with a chronic medical condition with a service dog who reacts to symptoms?
“It takes a very specific assessment to make sure that you have the right disease, coupled with the right dog, coupled with the right person,” says Raelynn Farnsworth, DVM, interim associate dean for clinical programs at Washington State University's College of Veterinary Medicine in Pullman, WA.
Dog Diagnosis? Not Yet
Someday, could dogs be trained to screen people for certain health conditions? That might not be such a far-fetched idea.
Dogs have a “tremendous ability to smell chemicals on so many different levels,” which already helps authorities with bomb and drug detection, Hartstein points out.
And don't forget “the sensitivity of a dog to very subtle behavioral changes in a person,” Singletary says.
One medical journal article by a dermatologist describes a woman whose dog repeatedly sniffed at, and was upset by, a mole on her back. That woman sought medical attention and was diagnosed with melanoma.
Still, even the smartest dog can't diagnose anything. So if your dog reacts differently and strongly to something on your body, you might want to consult a doctor -- who will put the best of human medicine to work.