
Bitches who have false, or phantom pregnancies usually continue to have them after each season, until spayed and this may well pull her down. As far as I'm aware, it's usually the bigger breeds who shouldn't be spayed early, giving their bones time to develop (growth plate closure) first. So if your bitch is a small breed and is suffering with a false pregnancy after her first season, I'd plan to get her spayed in another couple of months. And I'd go for a complete spay.
I took my Whippet in to be spayed when just over 6 months but not having had this breed before, I was not expecting him not to want to do it. I had no intention to breed from her and had an elderly (ill) entire male Basset at the time who didn't want to be anywhere near a bitch in season which he'd know about, even if she wasn't anywhere near where he was!! He suggested the potential for bone growth problems, and spay incontinence although I'm now not too sure he was right, having since moved away from the practice, for various reasons. I waited, making arrangements for her to go to a local kennel if she did come into season. By 10 - 11 months she'd still not come in so I took her back and asked him to go ahead, which he did and at 6 now, she's fine - perhaps a bit taller than she should be, but that could be genetic!!
I don't do castration unless medically necessary, but I will always spay, depending on my intentions for the bitch in question. If only not to have to confine them twice a year!! And Basset bitches do tend to run into false pregnancies.
ps You can still show a spayed bitch, with KC 'approval'.