in the manual under furnaces >> upgrades...
And to copy the manual entry:
Build labor
Skill
Buildmat
Dimension
Requirements
Architect & Animal Trainer
Animal Training
2 Chains, 2 Cages, 1 Science Discovery
5x5
Mason or Carpenter, Forge or Clothier, Researcher
building_war_kennels.txt
reaction_war_kennels.txt
You can train animals in this workshop. First you need to bring the animal to the kennels. Simply make a pasture on top of the workshop and assign the wanted animals there. You can do as many as you want in one go. Then run the reactions.
Combat training costs 1 stack of bones and trains all nearby creatures of the selected type. They will get 1 additional level in biting, dodging and melee combat, up till legendary.
You can armor a small list of animals with either iron or steel armor here. Shaggy Badgerdogs and Cragtooth Boars, Mastiffs, Horses, Grizzlies, Raptors, Elephants, Unicorns and more. This will both increase their defensive as well as offensive capabilities. Quite a lot, actually. You need iron or steel bars and mechanisms for this. If an armored creature is butchered, it will also create an inedible metal part. These parts can be recycled to gain back a bit of the metal.
Rune-Engraving an armored animal will triple its attributes.
An Example: The result will be a legendary biter, dodger and fighter steelclad war-mastiffs with three times the strength, toughness and agility as a normal one.
WARNING: Armored animals do not breed. Due to game mechanics they would give birth to already armored children. Don't armor all your warbeasts if you still want to breed them.