I have always used a general purpose collar, they can go through a lot of stress when you train a dog (depending on the size of your dog).
Also, when I take my dog out for a walk, I have Lisa (my dog) wearing a muzzle. I know she would not likely bite anyone, but here in the UK there are laws coming in soon that would imprison a dog owner if the dog bites people, not just a fine as it currently is. Plus, I don't want her to bite anyone - ever.
Getting back to the question, it really comes down to the size of the dog and the shape of their head vs. their neck. I have had a few collars that were just not right, but you will find one that fits and is comfortable for the dog.
