First - I have to address;
We don't do it to our kids because we want our children to reproduce.
Second, there are a LOT of myths being thrown around here. A lot not even related to dogs at all.
Yes, it's true that growth is slightly different in a neutered animal - but NOT
"Well, it makes them put on weight much more rapidly, their muscles do not develop normally and they are more tender"
Actually, it's the opposite. They get slightly taller, narrower and more feminine. They put on bone before muscle, and the muscle they put on is lighter and harder (think swimmer instead of football player). It is so very much the opposite of what has been claimed that there have been hormone supplements developed to encourage rapid weight gain in cattle - they contain testosterone (look it up)
Pig farmers have experimented with not castrating pigs, because 1) intact males gain faster and are more tender (yes, more tender, so long as they are growing - the meat is more tender because it is growing faster. MANY studies, look it up) and 2) It takes time and money to castrate.
The reason they still do it?
First, know that prey species have more testosterone in their systems than predators (so, yes, it is different for your dog, this is ALL less extreme) and testosterone DOES have an effect on behavior. Intact males housed with other males do more fighting, and intact males housed with females are endlessly "driven" and under lots of stress. Neither group gains well.
So, what does this mean for your dog?
A dog nuetered young will likely get slightly taller than a littermate who is not. He will be slightly more prone to being overweight - why? Because most dogs are over-fed and under-exercised, and he isn't fretting and stressing it off like his intact littermate is. If you let him (or any animal, or you) be overweight, there is an increased risk of diabetes, cushings and other metabolic disorders.
Oh, and yes, yes I have seen cushings in intact animals. Didn't even have to think about it. It happens at the same rate as for non-intact animals, there are just less intact ones, so I can understand how perhaps someone who doesn't deal with large numbers of animals might think that. I've worked with animals professionally for my entire life and yes, seen it.
The pay-off is;
~YES, there is a behavioral difference, and in some animals it is extreme. You have a mellow intact male? Great! Good for you!
They're not all like that. You have the exception.
It
does cut down on roaming and aggression. Does it eliminate it? Of course not, animals have personalities and multiple reasons for doing things, and, as I mentioned, MOST dogs are hugely under-exercised. But looking for love is a very, very significant reason for dogs to roam and fight. And should your dog do this, they are in mortal danger the whole time they are off your property. Roaming dogs get shot, beaten (I went out swinging a heavy broomstick at the dog who went after my dog in our own yard and if he made it home, I'm sure his owner had a vet bill to pay), hit by cars, etc. If vets were in it to make money at the expense of animals, they'd be anti-neuter!
~All that frustrated drive is a strain on the heart. The person who mentioned horses - stallions have a shorter life expectancy and are more prone to heart attack than geldings.
~There's not just testicular cancer, but also prostrate cancer and should an intact dog get any kind of cancer, it will progress somewhat faster. Humans take hormone suppressants as part of many cancer treatments.
~Did you know that humans are one of the few animals without a penile bone? Dogs have one. Like any bone, it can break. While not an incredibly common injury, barring a hard, abusive kick to the belly, it only happens to intact males in a state of arousal and is why many dog breeders make certain their dogs are leashed for the act - which your dog won't be if you don't know he's off doing something, or if he, in frustration, is getting too intimate with something he shouldn't. I'd rather remove "his nads" than all his male parts.
~Speaking of penile injury, penile and urethral prolapse are not uncommon in dogs. Intact males are also more prone to UTI and sheath infections. And then there's always STDs, like Brucellosis ... Which is zoonotic - you can then catch it from your dog
http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/brucellosis-dogs
Altogether, I have zero issues with "fixing" any animal I am not actively interested in breeding.
@Kusanar , about horses - I have a degree in horse care. Most people can't properly handle horses at all, throw excess testosterone in that and you have a recipe for disaster. My stallion is perfectly mannered - most professional's stallions, you'd have to peek underneath to be certain they ARE stallions. This myth doesn't come from pros - it comes from the machismo type who take huge pride in being able to manhandle their "fierce" stallions around, like that makes
their cahones bigger.
The 6 month, isolation, stall thing you're talking about leads to lots and lots of problems, testicles or not, but again, most people ...
Oh, and my stallion? When his breeding days are done, he's getting gelded. I want to have him for the longest time possible, I love that horse a lot.
