We have a bi-blue sheltie six years old we adopted four months ago and he wasn't used to wearing a collar and scratches at it now. I bought him a cloth collar thinking it was the metal chain he didn't like but he still scratched at his neck area a lot. I just found that he seems to be allergic to something in the tags or collar clip that has caused a red spot that is irritated exactly where his tags hang down. I did notice a little blackish gray on his chest hair and that is what made me think of metal allergy. I have allergy to nickel and it turns my skin black also. I felt so bad and ordered him plastic tags and took collar and all off until he heals. My question is that I put Neosporin on his skin and it looks better. Any other sheltie owners ever have this problem? Thanks in advance for your info. Debbie in Baton Rouge, LA