20-Year Prospect
So long as vapid heiresses buy purse-sized canines as fashion accessories and amusement parks house whales that can weigh six tons and measure 32 feet in length, there will be a need for animal trainers.
The problem is, you may not be able to find a job training the animal you want to train. Take horses: most Americans can't afford 'em. The purchase price of a decent horse comes in at around $5,000, and the annual cost of caring and maintaining a horse starts at about $2,500. If people can't shell out the cash for an equine companion, then there won't be any horses for you to train, will there?
In other words, any growth in this particular career field will be limited to dog-lovers. If you speak "woof," then you're all set. If you dream of training Shamu, then you might want to reconsider your options, because there just aren't that many killer whales to teach tricks to...and besides, haven't you seen Blackfish?