Why do they castrate horses for horse racing?
Uh, they don’t.
There’s no law against it. However, despite the fact that, it seems a mare is more likely to throw, it’s considered a good idea economically to have a winner who can produce offspring.
Gelding reduces the chances of injury by eliminating one of the most sensitive areas on a horse’s body, helps the horse stay more focused, and reduces aggressiveness, if that happens to be a problem. On the other hand, more testosterone does make a horse considerably stronger and more aggressive, so it’s more or less a break-even solution. It can also prevent a “faulty” bloodline from being passed on.
Your question is slightly flawed though, because in reality most racing horses are not gelded. In fact, on an interesting side-note, a gelded horse has never won the Triple Crown.
They don’t always and it’s not just in horse racing. Most male horses are castrated simply because it makes them a lot easier to work with, especially when they are younger. An uncastrated horse may be very aggressive and difficult and dangerous to handle. Some are almost impossible to handle unless they are castrated. The proximity of a mare in heat can cause some stallions to go crazy with the desire to copulate, and in such an instance there’s really no stopping 3/4 of a ton of muscle and testosterone. A stallion also has a strong tendency to fight other stallions.
There are sometimes health issues. An otherwise docile stallion may have an undescended testicle which can cause it very serious problems. The only answer is castration.
To clarify, I was only asking about geldings. I know not all horses are castrated. I was wondering why they ever do it.
Gelding’s (castrated male horses) are more even tempered than non-castrated horses. Young male horses (those used in racing) can be a contrary bunch. As a result you will have a harder time training them for the racetrack and they may be a problem on the track (they can be combative with other horses among other things). As a result a gelding is likely to run better than a non-castrated horse.
Of course, a winning horse can net you a fortune in stud fees. The real money a horse makes for its owner is not opn the track but as a stud. However, the majority of horses are not stud material. Something like 80-90% won’t be bred so most male horses will work out better as geldings.
Before they castrate a horse, can it produce semen? Can they collect some semen to sell later if the horse proves to be a great racer? Or is the horse too young?
I am sure you are wrong here. In Australia and the UK the vast majority of males are gelded by the time they are 3. The reason for the lack of Triple Crown winners is because most of the entrants are prospective stud stallions. The vast majority of racehorses have no prospects of ever having a stud career.
I have never known any place that provides riding animals to have any ungelded stallions, they are just too much trouble.
On a cheerier note when buying horses for learners you can be assured that a 12 year old gelding has a good nature because there is no reason to put up with one that doesn’t - they aren’t breeding stock.
Sorry I forgot to mention the other reason for gelding that hasn’t been mentioned is that it makes it easier to keep the horses weight down. When stallions retire and are let down for stud they become far more formidable specimens than geldings.
I’d note that in the case of Funny Cide, he had one undescended testicle which was throwing his stride off, so gelding was the solution adopted by the owners and trainer.
Jump racing is much more common in Ireland and the UK than it is in the States. Many horses are gelded because, to quote Ted Walsh, philosopher of the racecourse, “how would you like a yard brush run along your undercarriage”.