Answer
Lucy:
None that I can think of, except for the fact he can't reproduce (which, in my opinion, isn't a downside). There is a very small risk of complications, but they're very rare in males. All the dogs I've had have been spayed/neutered.
But keep in mind that neutering won't prevent a dog from wandering- only good training will stop that.
EDIT-
I've noticed a few people saying their dogs become lethargic and overweight. I'd forgotten that neutering can sometimes cause laziness which will lead to obesity, but it's never done that to any of mine, or to any of the dogs at the rescue I volunteer at. They're all as active as they ever were, so I'd say that depends on the dog.
Anonymous:
My dog got fixed at three months. And he's half the size of any lab I've seen, plus he's not even that much bigger than my chi. Well in height because she's got really long legs, but he's slightly taller and longer than her. So maybe at a young age it's bad for their growth, should probably wait till it stops growing. As for the fence thing, a good tazer(just the sound of it) will work, or an electric fence. Our gatee stays open almost all the time and our dogs never go out the gate.
Jack:
Neutering will prevent a dog from breeding, it is not a substitute for
training. It should not be done until a dog is done growing, which can
be 18 months or older in the larger breeds. If you get him neutered
then you will have a neutered dog who tries to get out of the gate.
Star-Of-Darkness:
None
They dont get fat. That's a sad myth. Dogs gt fat due to being over feed and not exercised
They wont get the many cancers only intact dogs get
They do better at training
Can't bred and pass its faulty genes on
Neuter the dog and train it
Shapoor:
Do not let the vet tell you it will not make him lethargic. I have had 2
different kinds of dogs and we had them 'snipped'. BOTH became couch
potatoes. Laying around allllll day. Only half hearted play ball. Put on
some weight also.
Jojo:
Having your dog castrated will NOT stop him trying to get out the gate.
More exercise and training is the answer to that problem.
Bluebonnet:
I am always for getting all pets spayed/neutered. They are just pet quality & not worthy of breeding.