The thing is, at a year old a dog the size of a bulldog probably isn't going to have a sex drive. Thud is now 19 months old. *He still doesn't even lift his leg to pee*, doesn't mark, and isn't even remotely acting like an intact male. Maybe it's training? I mean, Jack and Frost don't mark, but at least they lift their legs to pee outside. And when an intact dog in the house was in heat (Bug, who wasn't spayed as claimed) Frost was being mildly sniffy about it - Thud was 6 months or so at the time, but neither he nor (very) adult Jack even looked at her twice and like I said Frost didn't do more than sniffle vaguely. I found out mostly because I noticed she was swollen. The female next door has been in tact in the last month and neither of my three behaved in a way that would indicate they were even SLIGHTLY interested when walking by.
People keep coming up with all these extreme stories, and it just bewilders me because my experience is very, very different. Intact males and bitches in heat are in CONFORMATION RINGS TOGETHER, or acting like there's some big deal to keeping na intact dog and it's *not that hard*. Supervise your dog, keep it on a leash, and you are DONE. If your dog can get away from you for a bitch in heat, your bigger risk is it getting run over. Oops litters? Two intact dogs in a household where they are allowed loose together when no one is home, or a dog who is left loose to roam, chained, or otherwise outside (yeah, even in a fence) without no supervision at all and given adequate time to dig/climb/get out or another dog who happens to be around to get in. It's not going to happen on a potty trip.
It ain't that hard. It ESPECIALLY ain't that hard when you're dealing with an older puppy. It's not going to turn into a hormonal fuel uncontrollable rage machine EVER, but a large dog certainly isn't going to do it at a year old. A dog that age and that size probably is still going to be 98% puppy. Fertile, yes, but not even close to mature enough to be serious about it.