The biggest criticism of horse racing is that it is cruel. Naturally everyone has a different interpretation of what cruel is and is not. For some, even the thought of owning horses, and keeping them in stables and corrals is cruel. The fact is every year hundreds of horses will loose their lives as a result of breaking down on the race track. Others will be discarded for being too slow. Statistics vary from country to country, some areas do not even keep records, and of course we seldom hear about those horses who break down in training. Let us learn why some areas have more "accidents" than others.
Location
Horse racing is different world wide. In the United States, and Canada, for example, horses are kept pretty much at one race track for an extended period of time. Only the top horses tour the big races and go from track to track. These race tracks are typically located in urban areas and do not have any pastures, or riding space other than the tract itself, or exercise on the "hot walker". The horses are kept in their stalls for the greater part of the day, I will refer more to this below. In other countries, such as England the horses are kept mostly at home, shipped to race meets which generally are around two weeks long. These tracks are in rural locations allowing areas for riding. If you have attended a race meet in the United Kingdom you will notice right away that the horses are not "ponied" to the starting gate in the manner they are in North America. The riders seem to trust the horses a bit more, an indication that they are ridden more frequently and independent of racing and training. The race tracks themselves are often considered much more "humane" in the UK, being longer, they are often straight, or have varying direction, grassy, and so forth. Whereas the typical North American track is always a counter clockwise oval.
This is not to say that all racing in the United Kingdom is without criticism. National Hunt racing (formerly called Steeplechasing) is very hard on horses and every year several horses lose their lives in this dangerous sport. The risk is so great, that it is usually only geldings who race in these races.
Age
Race horse owners and the industry itself, push to get their horses on the track early. Regardless of actual date of birth, horses in the Northern Hemisphere are considered to have the birth date of January 1st of the year they were born. So if a foal is born in May, it is considered to be the same age as a horse born in January of that year. There are races for 2-year-olds. In an eager attempt to get these youngsters on the track they are saddled and ridden as yearlings, something not done in any other discipline. Many Warmbloods, (horses commonly used for jumping) are not even ridden until 4 or 5 years of age, much less pushed to their maximum capacity at that age.
The races for 2 year olds are short distance races. This is actually very hard on them because they are sprinting the whole time, which is difficult on a young, undeveloped, horse.
Stabling
When a horse remains in a stall for a good part of the day, its bone density deteriorates, thus the bones become weaker. This has been shown in people who do not get enough exercise and is probably a big reason for so many horses breaking down on the track.
Race track stabling houses hundreds of horses, there is simply not enough space to have turn out pastures or pens for all of them in this situation. As I have stated, in North America, this means the horses are in their stalls for most of the day, for most of the year. Also, even if such spaces did exist, high energy horses would want to play, and playing is risky. Horse owners often do not want to risk their horse being injured, as such, the stall is a safer choice. Certainly more boring, but safer.
Race Horses are not Pets
Race horses are status symbols and a tool to make money for their owner. Many race horse owners could not pick their horse out of a field, and it's probably just as well, since many wouldn't be able to put a halter on if they had to. The horse is a commodity to be used then sold or bred. The horses are usually cared for by trainers and grooms, not by their owners. It is a common misconception that race horses are treated like royalty. Very few are top dollar earners, but those who are not, are flogged until they break down or are sold.
Thoroughbred vs Standardbred Racing
For the most part Standardbred racing is much less risky to the horse in terms of stress and injury. Standardbreds are the ones that race with the carts behind them (not to be confused with Chuckwagon Racing). Thoroughbreds race at top speed, the gallop, whereas Standardbreds race at a slower gait, the trot or pace. This means less stress on the whole, and as a result there are fewer injuries, except in the case of collisions.
Gambling
Another concern about horse racing is the gambling aspect. Gambling can be addictive, and expensive,s as a person chase that "big win". Gambling does not concern the horses unless they are tampered with to fix a race.
So there you have it, the negative aspects of horse racing. In most countries laws have been passed to try to eliminate much of the cruelty, for example jockeys are only allowed to use their whip a certain amount, and for certain times. You can decide for yourself if it is a cruel sport or not.