Dogs who have long hair or a thick undercoat are prone to developing mats. The best way to keep your dog from developing mats is to groom him regularly, daily if necessary, using the proper tools. There are many different choices in combs and brushes, but you need to select ones that you are comfortable using and that get down to your dog's skin, not ones that just smooth the top surface of the hair.
Metal combs make it easy to get right to the base of any tangles and work them loose before they develop into a mat. Many metal grooming combs have widely spaced teeth on one side that gradually get closer toward the other end. This allows you to comb through the coat, and if you hit a snag, switch the comb around and use the widely spaced teeth to work it loose. Metal combs are also easy to maneuver in tight spots, such as where your dog's legs attach to his body and between his front legs.
A slicker brush works well on many different coat types and is a versatile addition to your grooming kit. The slicker brush is rectangular with a flat base. The bristles are made of short, fine wires. This brush gets right down to your dog's skin to keep tangles from forming, but it is important to be gentle when using it. If you brush your dog too aggressively with the slicker brush you can scratch and irritate his skin.
Rakes are a great choice for dogs with a thick undercoat. They get close to the skin and remove tangles and dead hair that will develop into mats. A rake is typically shaped like a "T," with the top housing closely spaced bristles, and the lower part serving as the handle. Rakes come with different length bristles. Select a rake that has bristles about the same length as your dog's coat. If they are too short, they won't penetrate through the thick undercoat to the skin, and if they are too long they can scratch the skin.
A pin brush is not the only brush you should use on your dog if he has fur that mats, but it makes a good finishing tool. The pin brush looks a lot like a regular human brush, with a handle and an oval-shaped head. The metal pins are set in a cushion and there are small balls on the tip of each pin, making this brush a gentle option. The pin brush doesn't get to the base of a tangled coat, but it does an excellent job of smoothing the hair down when you are done working through it with another grooming tool and removes any remaining dead hairs.