There are 2 things wrong about the Wardog unit:

Firstly, in real life, Wardogs would eventually lose interest if they become very tired in pursuit. Ive seen a band of Wardogs chase 3 chariots off the entire length of the field.

Secontly, also unrealistically, they are too disciplined. If you charge them into a line of troops, they will attack ONLY the unit you sent them against. In real life, they would break off and attack anything that moves!