When a bitch is spayed are the ovaries removed or just the uterus? If both are removed then why? Any answers? I meant to ask our vet last time I was there but forgot!

Yes, both are removed.  If you don't remove the ovaries they continue to cycle hormones that would attract unwanted attention from males and if you did not remove the uterus she would remain at risk to pyometra which is reasonably common, particularly in later life when anaesthetic becomes more risky.

Thanks Isabel. I was just wondering because in humans (for different reasons obviously) sometimes it's a hysterectomy alone and sometimes an oophorectomy will be done and sometimes both together. But then I suppose human female hormones don't have quite such a dramatic effect on men do they!!!

Thats not quite true. An experiment was done on whether men were attracted to certain types of women by their smell.
I think 30 women wore identicle t-shirts for a day and a night.
All t-shirts were put into identicle bags and sealed.
Cant remember the number but many men where then asked to smell the t-shirts and asked to choice which they were most attracted to.
All the men choose the one woman who was in oestrus at the time of wearing the t-shirt.

Really! That's quite amazing!