When we moved here, we noticed that there is a different culture with respect to the care of domestic cats. No one spays and neuters...they even made it FREE here where I live...and they have plenty of kill shelters, and a constant stream of free kittens online and in the paper. Have you seen the pictures in the kill shelters of the piles of bodies? That would be easily avoidable, if people cared enough to spay and neuter, or if they realized that Pookie does not need at least ....one litter... /FACEPALM.
At least with horses/cows/goats/pigs the deaths can serve some sort of purpose...to what purpose is the deaths from euthanasia at a kill shelter serve?
I agree that people should be sterilizing their pets, but I don't personally think you can compare the overpopulation of stray cats and dogs to that of horses. In general, horses are not running feral, in every neighbor hood of the US, breeding all by themselves. The percentage of genuine accidental horses is negligible.
What we need to have in place is a system where people have to apply for a certificate for each breeding and pay money to file the the paper work. It need only be a nominal fee to discourage what I consider idle breeders. Then fine the snot out of anyone who tries to sell a horse without the proper certificate. This, imo, would bring a screeching halt to those breedings where someone goes "I have a mare that has stood unbroken and good for nothing all her life and you have a stallion that is not butt-ugly in the right light, let's breed them."
This would create jobs and bring in money in the way of fees and fines to fund itself. I am also not suggesting that the government have any say in the actual crosses you can breed or anything like that, but if you are serious about breeding your mare, you simply submit a nominal fee and a short worksheet saying that you are going to do so and in what year it will take place to avoid the switching of certificates.
That being said, I think the TB racing industry could keep the slaughter houses in business even with legitimate breedings.