Stylish dog collars fill the racks at pet supply stores, but are more than mere fashion accessories for your dog. His collar serves as his identification that he belongs to someone. A dog on the loose who's wearing a collar and ID tags is more likely to be returned to his owner, and less likely to be thought a stray dog and end up in an animal shelter.

Collars can slip off, so a tattoo or microchip ID should be used as a secondary method of identifying your dog. These methods aren't foolproof, either, so a combination of a collar with ID tags and either a tattoo or microchip is best.

Your dog may need more than one collar: A basic collar with ID tags for everyday wear and a training collar for obedience lessons and other behavior training. Using the right type of collar, and using it correctly, can make training sessions more effective.http://www.neilsnet.com/archives/collars/collars.shtml

Your dog’s everyday collar should be a basic model with a buckle closure and a metal ring for his ID tags and a leash. To find the right size, measure your dog’s neck an inch or two below his head (closer for smaller dogs, further down the neck for larger breeds). Add one inch to the measurement for small to medium dogs and two inches for larger dogs. http://www.petproductadvisor.com/buyers-guide/selecting-the-right-collar-for-your-dog/109/page1.aspx

Collars come in even sizes, so choose the larger size if your dog’s neck measurements fall in between. When fastened around your dog’s neck, the collar should be loose enough to slip two fingers under it if your dog is medium-sized, one for a very small dog and three for a larger dog.http://www.petproductadvisor.com/buyers-guide/selecting-the-right-collar-for-your-dog/109/page1.aspx

Collars with quick-release buckles are safest choice for multi-dog homes, since dogs may get tangled in each other’s collars during playtime. These plastic buckles are easy for the owner to unfasten even when there is tension on the collar, and can reduce the dogs’ chances of accidentally choking one another.

Dogs who tend to lunge at the end of their tethers should have sturdy collars with traditional metal buckles; plastic buckles may break. Dogs who are left alone for long periods of time should have break-away collars that will come off if they become snagged on something. Your dog's struggling to break free will release the collar and prevent him from accidental strangulation. Break-away collars have two metals rings to snap the leash through so that the collar can't come off when the dog is tethered.http://www.neilsnet.com/archives/collars/collars.shtml

Slip collars can be useful in dog obedience training. Although "choker chains" are illegal in some states, when slip collars are used correctly they cause no real physical pain or discomfort to the dog. http://www.neilsnet.com/archives/collars/collars.shtml

Some people mistakenly believe that the goal of using a slip collar is to teach a dog not to pull at the end of a leash. Any dog owner who's seen his dog nearly strangulate himself trying to go after a small animal knows this doesn't always work! Used correctly, the loose end of the collar is attached to the leash and given a gentle "slap" to make the chain rattle and gain the dog's attention or distract him from misbehavior. http://www.neilsnet.com/archives/collars/collars.shtml

A slip collar is dangerous as an everyday collar, since it can easily get snagged. Your dog may choke to death if you aren't around to rescue him in time. Always remove a chain collar from your dog's neck when the training session is over.

Electronic training collars use mild electrical current, vibration, or tone to correct dog behavior. This type of collar should only be used by a skilled dog handler, since the controversial method has the potential for misuse and abuse.http://www.petproductadvisor.com/buyers-guide/selecting-the-right-collar-for-your-dog/109/page1.aspx

A harness is often used in place of a collar for the purposes of dog obedience training or as work equipment. Carting dogs and sled dogs wear harnesses to give them added pulling power.

Owners may use harnesses or head halters for control when their dogs are resistant to lead training, but the head harness is the better choice. A harness will actually encourage the dog to pull even more, which is why sled dogs wear them. The head halter allows the owner to lead the dog by the head instead of the neck, and will help teach your dog to follow you instead of lunging away; where the dog's head goes, the dog will go. Head halters must be carefully fitted and adjusted to avoid digging into the dog's eyes and muzzle.http://www.animalbehavior.net/LIBRARY/Canine/PPM/DogHeadHalters.htm

Martingale collars are often recommended for dogs (particularly sight hounds) whose narrow heads let them slip easily out of standard collars. The Martingale collar has two loops; the smaller loop tightens the larger loop around the dog's neck when it is pulled.http://martingaledogcollars.org/