Having Collies with slim heads similar to greyhounds, I use martingale collars on them too, for obedience and walking around the neighborhood. For agility or hiking though, I go ahead and use regular flat buckle collars. Too easy for their collar to get hung on something and I'd much rather in those cases for them to be able to pull their head through. I don't really worry about them running from me, so I feel like the hanging risk is higher.

Par...