
Hi Josie!
When I've had bitches spayed I've always been guided by my old vet, who advocated spaying midway between seasons, never before the first one unless it was a medical emergency. There are many reasons for this, not least the fact that the blood supply to the uterus is at a normal level, so surgery is easier and safer, and also the hormones are at their lowest level, so there's less risk of behavioural problems.
There are side-effects of spaying, but they're not terribly common, and can usually be treated.
Weight gain: there's no doubt that some bitches
do put on weight after spaying, no matter how little they're fed or how much exercise they're given, but experience seems to point to that being more the case with bitches who're spayed after having a litter, rather than maiden bitches. If others put on weight it's generally because we let them (like ourselves!)
Personality changes: not common, especially if the bitch was mature when spayed.
Coat changes: not normally a problem in smooth-coated breeds.
Urinary incontinence: It's not uncommon for elderly bitches to experience a degree of incontinence (just like elderly people!) but bitches who were spayed before their first season are more likely suffer this from a much younger age than would otherwise be expected. This can be treated with lifelong medication.
If she's spayed you'll never have to worry about her coming into season and attracting dogs to your door! It is indeed major surgery, but vets have a lot of experience with the operation, and anaesthetics are a lot safer than they used to be, although naturally there's always a risk with any surgery. Even in unspayed bitches the incidence of mammary cancer is very low (it seems to be about the same risk as with people). The risk of pyometra in unspayed bitches is rather higher than the cancer risk, and to be honest that's the only
health concern that would personally sway me. But that's just my opinion!
To sum up a rather lengthy post (sorry!), if you're going to have her spayed, do it about 3 months after a season, either her first or her second. Hope this helps.
:)