Besides the classic dog collar that people tend to imagine, the kind you see in old cartoons with a tag hanging off of it, there are slip collars (also known as choke collars), prong collars, and martingale collars. The opinions that people have about these type of collars is about as various as the types of collars that are made.
Depending on who you're talking to, you may hear that prong collars are worse than choke collars, choke collars are worse than prong collars, or that prong collars are the only way to go. PETA warns of the dangers of both choke and prong collars, and while there is a real danger when it comes to using these type of collars -- it's largely related to how the leash is being used; not the leash itself.
Expert dog trainer, Suzanne Clothier, gives an insightful account of prong and choke collars on her blog. Though she does not advocate their use, she points out some instances where they've been useful -- her blog post "training with the prong collar" will give you a good idea of how and when a prong should be used. One thing readers may find surprising (if they read Suzanne Clothier's article) is that Hans Tossutti (one of America's earliest obedience trainers) considered the prong collar to be much more humane than the choke.
According to most trainers, if you're dog is a "puller" and you can't teach them to heel and have thus considered investing in equipment mentioned in this article... you may want to start with your basic choke/slip collar -- these come in various materials... ranging from bungee material, nylon, to cloth, to chain. The important thing when using a choke collar is to make sure it's fitted properly to your dog.
"FItted properly?!?" you ask... "But, the slip fits itself." Yes, to a certain extent it does. However, it's important that when you're setting up the loop for the slip/choke, that the tightness of the loop eases off when no pressure is applied. If you don't test this, and get the loop on backwards, the choke collar can become very uncomfortable and even dangerous for your dog as it tightens without giving slack. To a certain extent this is more a matter of the material used for this type of collar than anything else. The proper way to make a choke collar effective is by means of a leash correction.
In the video below this dog trainer shows how to properly fit chokes, prongs, and even gentle leaders.
As for prong collars, that's mostly if the choke collar isn't working. As the trainer in the video mentions, she considers the prong collar a last resort. Other trainers are of the different opinion to start right with the prong collar (they come in metal or plastic) and are considered a quick path to mastering obedience. Again though, as mentioned in the Suzanne Clothier article, this is only if they are used the way they are intended.
To close this article on a happy note, martingale collars are considered the happy non-controversial medium by almost everyone. They apply pressure equally to your dog's neck (as opposed to just the front of it) and they are more quick to ease up. Check out CollarGirl.com's article on martingales to get a sense of all the benefits they offer.
To close on the happiest note... if you and your dog walker spend lots of time with your dog and it learns to heel and enjoy easy going walks... then it's time to get your dog a nice embroidered collar! Tags can fall off and all you have to rely on is the chip (if your dog is chipped). An embroidered collar isn't going to come off like a tag, plus it's quite stylish!
Stay tuned for Part IV... gentle leaders and the future of dog tech!