#1) NECK DAMAGE Repeated stress on the neck can lead to long-term medical issues like damaging the thyroid glands and tissues around the neck area and salivary glands. A harness is much better at dispersing pressure evenly over the body instead of all the pressure one one area, the neck. The neck is sensitive and should not have repeated stress applied to it on a daily basis or ever.
#2) IRRITABILITY Your dog’s neck is very sensitive so, hooking up to a collar is very uncomfortable to a dog. And if your dog doesn’t show that, it doesn’t mean that your dog isn’t uncomfortable. Take your fingers and squeeze around your neck. It doesn't feel good does it? Your dog feels that times ten on every walk you take if you use a collar AND your dog pulls or you pull and pop the leash. Your dog can enjoy walking so much or meeting people so much, that the collar is ignored because the joy of going our and/or meeting new people/exploring outweighs the discomfort.
#3) ASSOCIATIVE LEARNING Keep in mind that one of the main ways dogs learn, is through associations. That means that your dog is making associations just like we are, every day but, on a much larger scale. So, if your dog is irritated by the collar already, then your dog may associate other dogs with being on the annoying collar.
