This idea has amused me since I first saw the April Fools topic about Horses (Which I think we need, by the way!)
Guard Dogs; tamed animals (foxes?) that can be kept within a personal claim/within a house/within a fence that attack anyone who ventures into the area without proper permissions.
Fed with Meat in a "Dog Bowl" (Wooden/anotheruseformetal)
As your relationship with the dog increases, it can protect a larger area.
Could also be used to track scents/older scents?
Could also "herd" animals? (Perhaps be sent to bring a cow or sheep to the player)
Could have similar stats and be breedable like the other animals. Loyalty (an unloyal dog may attack its master or just ignore an intruder), Intelligence (stupid dog might not do anything), Ferocity?
EDIT: Strength, of course - how much damage it does to whatever it's attacking.
This would give players a way to protect their things while they're not online.
Also!
Dog sleds. Hunting dogs.
HnH needs pets!