I always castrate at the end of the winter as they become a yearling. Wait until the ground is dry enough and save them a small clean paddock, before flies come out.
I prefer them to not know what Spring hormones feel like, but to give them a tiny bit longer to develop rather than cut as young foals
I prefer to geld at 2.5 years old. So it'd probably be the beginning of winter or the end of winter/the beginning of their 3 year old year.
However, I understand that not everyone has the set-up for this, so sometimes you have to do things earlier. In addition to that, some colts can become a handful, and that might encourage people to geld earlier.
I prefer it from a development perspective and haven't had an issue with mine. Last one was gelded at 3.5. He did get a bit interested when mares were in heat on a shared fence line, or if he was in with a mare, but not any more than I've seen other geldings get interested.
I think a lot of it comes down to genetics, management, and the individual.
I've just had mine done (10 months). Both testicles were fully dropped, but only little. He's quite a big lad already so it didn't feel too soon, and he's in a lovely dry field. Plus the flies aren't out yet.
My mare's son was getting a bit full of himself, and he lived with mares at a livery yard, so no one wanted to take any risks. Unplanned equine teenage pregnancies stop here. Snippy snippy ASAP, which was about eight months old.
My ISH was done at 20 months, coming out of the winter of his second year. It seemed the right now. He was well developed, physically, and polite, but my mare was starting to get aggy over the fence towards him and I wanted them all together in the same field again for the summer. Typically, he sucked one testicle back up despite them having dropped a year earlier, and so he had to be done in the clinic rather than at home!
Right now, we have an 8-mth colt who is smooth as a ken doll still! Daily ball checks are in place as I reeeeeeeally want him out for the summer. He's only a pony-colt and he needs to run with the herd.
Thanks everyone. Mine is booked in for this month (he will be 12 months old). I was contemplating leaving him until he was 18 months, as he's nice and easy to handle and we only have geldings here. But it would be simply to fill him out a bit more. However I've since read that any stallion muscle/crest they do develop would dissappear anyway once he's cut, so I may aswell stick with the original plan and get him done now. I did own an ex breeding stallion for 21yrs and he always retained his stallion look (and behavior). But he wasn't cut until he was about 8yrs old and I'm certainly not waiting that long with my colt. It'd either be now, or this autumn. My previous horse was also a Welsh D, which tend to look a bit more powerful anyway. This current one is a KWPN.