I'm sure I remember conversion factors for handling aging for animals but I can't seem to find them any more. How should aging of (significant) animals be handled. RAW preferably.
There is a table and rules in Grogs, on page 138, for aging animals.
It groups animals into 4 groups and gives a suggested age for the animals to begin aging along with a modifier to the aging roll and the frequency of aging rolls.
For example, hoofed animals are given as starting aging at 20 years, have a +1 modifier per 5 years, and aging rolls every 2 years.