Dogs with undercoats do need regular baths. These dogs benefit from frequent brushing and occasional baths.
The undercoat is a dense layer of fur underneath a top layer of guard hair. Double-coated breeds were bred for outdoor work in fields, hunting or herding livestock. They come in all sizes. Terrier breeds such as the Irish, Norfolk, Scottish and Sealyham have double coats, as do working breeds such as the Akita, the malamute, the Bernese mountain dog, the Samoyed, the husky and the Tibetan terrier. Many herding breeds are double-coated, including the rough collie, the Shetland sheepdog, the border collie, the German shepherd and the old English sheepdog.
When to Bathe
Breeds with double coats tend to shed more hair than single-coated dogs. If their coats are not maintained, they can become matted and tangled readily. Heavy shedding in these breeds occurs in the spring and fall. Double-coated dogs should be bathed during shedding to keep their skin healthy and encourage the old undercoat to shed. Otherwise, you can bathe your dog up to four or so times per year without risk of stripping the oils from his fur, drying his skin and risking his health.
Brushing Is Vital
If your dog has an undercoat, it's important to brush him several times a week. Brushing distributes the oil from the dog's skin, keeps the coat healthy and removes dirt or particles. It also prevents mats and tangles, which can go unnoticed if you don't brush the dog regularly. Mist the coat with water from a spray bottle first to avoid breaking the hair, then use a pin brush followed by a slicker brush to remove dead hair and keep the coat healthy.
Brush Before Bathing
Always brush your double-coated dog thoroughly before giving him a bath. Loose hair can become tangled when it's wet, and it will be more difficult and painful for the dog to remove afterward. Mist the coat, and brush one section at a time to be sure you get down to the skin. Once your dog has been thoroughly brushed, he's ready for the bathtub.
Use a shampoo made for dogs rather than one for humans. Human shampoo has a different pH than dog shampoo, and it can hurt your dog's coat or skin. Wet your dog well with warm, not hot, water. Work the water through his undercoat to the skin. Apply a line of shampoo down his back and lather well. Shampoo the legs, then use a washcloth to clean your dog's face. Avoid getting soap in his eyes or water in his ears. Rinse the dog well with a spray nozzle, taking care to get all the way through the undercoat. Use a conditioner made for dogs to make the heavy coat more manageable, and rinse again.