What kind of rewards?

So far:

When the pet was new and small:

• 20k- 5 Gold Ingots (in a partial stack)

Now that the pet is an adult and it's size is that of a "full" Golden Pig:

• 1k- 1 Gold Ore (large)
• 1k- 40 Gold

I'll be testing more frequently. It seems to me that this pig's "ability" is a waste of time.

At age 127 years past 25, it takes less than 1k gold to reach full size and the reward tends to be 50-300 gold. It appears the cost/rewards decrease as the pet ages, and it is essentially never worth the cost.