Dog Collars are a repop item worn by all wookie dogs. This is the neckware of choice for fighter types in from level 73 or so, to level 90. They are the best +dam neckware until Square Scarfs.
Dog Collar's are typically level 75 - 78, but can be as low as level 73.
Here is what identify reveals about this item:
Object 'collar' is type armor, extra flags none.
Weight is 5, value is 0, level is 76.
Armor class is 13.
Worn:Takeable Neck
Affects damage roll by 10.
Affects hp by -75.
Affects mana by -100.