Here's a rough stab at their stats. I decided to make them Medium, since 12 Hit Dice seems too high for a Small Golem. Besides 2' tall is fairly big for a dog. Assuming it's at the shoulder, a sturdy Rotweiler type could easily be that tall and Medium-sized.
Firedog
Medium Construct
Hit Dice: 12d10+20 (86 hp)
Initiative: +0
Speed: 20 ft. (4 squares)
Armor Class: 30 (+20 natural), touch 10, flat-footed 30
Base Attack/Grapple: +9/+10
Attack: Bite +15 melee (1d10+7)
Full Attack: Bite +15 melee (1d10+7)
Space/Reach: 5 ft./5 ft.
Special Attacks: Breath weapon [10 ft. cube of poison gas, 1d4/3d4 Con, Fort DC 16], trip
Special Qualities: Construct traits, damage reduction 15/adamantine, darkvision 60 ft., fire resistance 15 or immunity to fire, immunity to magic, low-light vision
Saves: Fort +4, Ref +4, Will +4
Abilities: Str 25, Dex 11, Con —, Int —, Wis 11, Cha 1
Skills: — [Survival?]
Feats: — [Track?]
Environment: Any
Organization: Solitary or pair
Challenge Rating: 10?
Treasure: None
Alignment: Always neutral
Advancement: 13-17 HD (Medium); 18-24 (Large); 25-36 (Huge)
Level Adjustment: —