Here’s the simple truth: dogs don’t actually need to be bathed. The oils on their skin and hair help retain moisture, and the scents they accumulate in their day-to-day excursions alert other dogs to where they have been and what they have seen. It’s an important aspect of the canine communication process.
That said, dogs don’t live just with each other; they live with us, and we may see things differently. “If I had a dog who rolled around in stuff and got all muddy outside, absolutely I’d like him to have a bath,” says Tufts veterinary dermatologist Andrea Lam, DVM. Most people also want their dogs clean if their pets sleep on the bed or lie around on the couch or rugs — and every pet dog has to lie somewhere. That’s why bathing is part of dog ownership. But is there a right way to do it?
Yes. First, it’s “best to use a gentle cleaning shampoo,” Dr. Lam says, “maybe something oatmeal based. And it should definitely be a dog shampoo, not one for people.” Human skin has a different ph. It’s more acidic, with a ph in the range of 5.4 to 5.9, rather than the range of 6.2 to 7.4 more typical for a dog. Thus, shampoos manufactured for people could wash away a dog’s acid mantle, a lightly acidic layer on the skin that serves as a barrier to environmental contaminants like bacteria and viruses. And that can make a smelly dog’s odor even worse. The bacteria that proliferate on a dog as a result of the stripped-away protective layer can end up adding an unpleasant scent of their own. Indeed, some people who use shampoo for people to wash their dogs end up perpetuating the problem; they over-bathe in an attempt to get rid of the smell, only leaving the skin more prone to hosting the growth of odor-causing bacteria.
Over-bathing with a shampoo for people will also leave a dog’s skin dry and often irritated. Keep in mind that a dog’s skin is thinner than ours; the more hair on the body that can act as a barrier to outside contaminants, the thinner the species’ skin.
Once you purchase a shampoo for dogs, it’s fine to bathe them every month or two. Get your pet in the tub a little more frequently if you must, but more than every couple of weeks is probably not a good idea, and more than once a week is definitely pushing it in terms of your dog’s optimal health.
Thorough rinsing is key. “Make super-sure you get all the suds out,” says Dr. Lam, “because if shampoo remains stuck in the hair coat, it can actually lead to some infection under there. There’s now a constant area of dampness that’s a friendly environment for harmful bacteria and other pathogens.”