I’d definitely do a harness for such a tiny fella… Possibly if you do good leash-training (teaching a proper heel, or at least teach him to ALWAYS keep a loose leash), then you could go over to a collar. My guy is microchipped, and only wears a collar when he’s in public. He lives in an outdoor kennel run, and there are certain spots in the fencing where he has snagged and pulled out of his collar (I was lucky it was loose enough he could pull out of there…). That was the very last time I let him (and my other dog, who’s worn a collar 24-7 his whole life) wear a collar while unsupervised.
Since my dogs are thoroughly trained on the leash (okay, Loki is in the /process/ of it), I honestly don’t think too much about what to have them wear. Sometimes I pop on a harness just because it looks cute, other times I get the pinch collar out if they’re being obnoxious. But then again, they’re 40-70lb dogs. I’d probably never use /any/ collar when initially training a tiny dog.
