My 1 and 1/2 year old GS has a ring of hairless/thinning fur around its neck, where the collar is. Havent noticed it before until today when I took out the collar and gave him a bath. I think it might due to the polyester collar but im not sure. Its not to tight and it fits him although he did do some amount of pulling before being trained. No where else in his body is he losing hair other than regular shedding. Any suggestions, tips, causes, or solutions? Thanks!