LOLOL ... my knowledge of 'horse stuff' stems entirely from mucking out 18 stalls three times every week; so, I suppose you could say it amounts to horse pucky!
I reckon there's about 100 hours of really hard work for every minute spent in a show ring. Before my dad would ever let me take my first jump there was two years of twice weekly dressage lessons. And we didn't do rodeo on our farm -- foals were put on a lead as soon as their little heads would fit a halter, then two and a half years on lounge line and ground driving. By the time an animal was developed enough to ride he'd already worn a saddle for months; getting on and riding was then a piece of cake. Thank GAWD Sims Pets circumvents all that.
I kind of wish Sims 3 Pets was a little more like gardening, where each succeeding generation is better than the last -- the goal of animal husbandry is to improve the breed -- so, with careful selection of mates for extant breeding stock the offspring are USUALLY better than their forebears (and more valuable). This is most effectively characterized in a game by demonstrating improved performance; vis a vis racing/jumping/cross country competitions. I really do hope EA can add this component at some point. There would then be a reason for continued play well beyond achievement of the Lifetime Wish. But that's just me
I still hope EA will come out with a Farm expansion, where we get cows, chickens, and pigs. The purpose would be to breed animals that yield higher produce over a series of generations (and with careful breeding). Perhaps the mechanism allowing such game progression could be extended to horses, dogs, and cats. With Pets, the foundation is certainly in place. An add-on would include a county fair, with midway and livestock competitions (much like the competitions at the current equestrian center). Barn dances would provide temporary respite for hardworking sim farmers/ranchers.