A dogs coat can give you an insight on its preferred living environment. Double-coated were design to keep the dogs warm and equipped in the cold. Where as short-coated dogs were developed to live in hot climates. A dogs coat also gives an insight on the dogs history. Retrievers have thick, water repellent coats for when the retrieve fishing nets and Terriers have rough wiry coats to withstand the elements.
Single Coats - Single Coated dogs have one layer of fur, like the Boxer, Chihuahua, and the Boston Terrier. Dogs with this coat have the lowest grooming requirements. These dogs only need a quick brushing, with a rubber brush, once a week. However, some Single coated dogs like the Yorkie or the Maltese, have long coats and require more grooming.
Double Coated - Double Coated dogs in addition to the single coat have an under coat. These dogs like the Collie, Labs, and Spaniels shed in fall to produce a thicker coat in the winter, and then again in the spring to develop a lighter coat for summer. Therefore, dogs with a double coat need more brushing and some more during the shedding season.
Whether single or double coated, all dogs shed. There is no such thing as a hyper allergenic dog. In fact most people are allergic to the dogs saliva or a dogs dander. And all dogs, even hairless or curly ones, produce both.
Smooth Coats - Dogs like Whippets, Greyhounds, and Great Danes have a short, fine coat that kind of lays on the dogs skin. These dogs have little to no undercoat and are easy to groom.
Silky Coats - Dogs like Afghan Hounds, Maltese, and Silky Terriers have long, fine, thin coats designed to keep them cool. Although they have no undercoat they need to be groomed daily to prevent matting, where hair clumps together.
Wiry Coats - Dogs like Border Terriers have Wiry coats designed to withstand the elements. Dogs with this kind of coat need hand striping, where the dead undercoat is stripped away to allow new fur to grow. Strip every 6-8 weeks.
Curly Coats - The Poodle, Bishon Frise, and Porteguese Water Dog have curly coats. This coat type sheds less dander and fur, so are good for allergy sufferers. Since their coats don't shed as much all you have to worry about is constant trimming. Groom at least twice a week.
Corded Coats - The Komondor and Puli have corded coats designed to be weather resistant. This coat type is the hardest to groom. The coat consists of a soft undercoat and a perfused top layer, and as the two tangle together they form cords. You have to remove all the debree and split the cords one by one down to the skin to be separated. Bathe them afterward and blow dry quickly, it can take up to 3 days to air dry. This coat type needs bathing every 6-8 weeks, and the fur around the eyes needs to be trimmed.
A Shiny Coat
If your dog's coat seems dull, dry, or brittle, it might not be given food with a good quality. Change the dog food, adjust the omega-6/omega-3 fatty acid ratio in its diet. A dog with a shinier coat is healthier.
Hairless - Hairless dogs seem like they don't need a lot of coat care, but the hairless part is what needs attention. You need to wash them with a cloth on a regular basis, moisturize their skin so it doesn't dry out, and use sun block to avoid a sunburn.
Short Coat - The easiest to groom and don't shed as much.
Medium Coat - Requires regular brushing.
Long Coat - Longer coats need daily brushing to avoid matting.