|The following is based on Fallout 2 cut content and has not been confirmed by canon sources.|
A dusty old set of sturdy kevlar plates set into black nylon sleeves. You think it must be sized for a dwarf, until you notice a tag on the inside which reads: Canine Kevlar. Large. A DoggieBuddy product. Made in Taiwan.”— Game file description
This item was to be issued to K9 dogs for their protection.
Liz in the Broken Hills' hardware store sells it. If she was asked for something special she would take one off the shelves and set the Chosen One up for a mere $2000, but only if they have Dogmeat in company. When Dogmeat is fully leveled up and wearing the armor, he will have the equivalent protection of combat armor.
While not featured in the final version of Fallout 2, it can still be found in the game files.