If you loose the collar, you can lose the dog.

[jobycom]

If you lose the collar, you can loose the dog.

[TrogL]

1. it's "loosen" the collar, "loose" is not a verb

[jobycom]

2. Any word can be verbed.

http://www.merriam-webster.com/dictionary/loose

1 a : to let loose : release b : to free from restraint
2 : to make loose : untie <loose a knot>
3 : to cast loose : detach
4 : to let fly : discharge
5 : to make less rigid, tight, or strict : relax
intransitive verb
: to let fly a missile (as an arrow) : fire

[Bucky]

3. I think English is a good deal more elastic that you want to admit.

If someone uses loose as a verb and everyone understands what she means, by criminy it's a verb. And there's not a damn thing you can do about, old man-- not one damn thing. Us kids are gonna go out and smoke weed and listen to mother nature and make a beautiful world, man, with none of your generation's hang ups and rules, man, with free love and groovy music and painted chicks dancin' in cages at the Underground Discotheque a-Go Go, daddy-0, and it'll be boss.