my bitch had a c-section yesterday and has just started to strain again. is this normal? I am  very concerned. waiting for the vet to call back...........

No, not in my experience anyway (although I've only ever dealth with them in cats, never had to have one in a bitch) but it is possible that an afterbirth or even a pup was left behind. When one of my cats had a c-section the vet left an afterbirth behind and it led to all sorts of trouble after a day or two when it needed to come out and she started straining.

I've had two girls who have had sections, but neither of them started straining,  I should ring your vet and ask, too much straining after this op could be dangerous, she could rupture her stitches.

Let us know what they say

just spoken to the vet. it is not normal but not uncommon for a bitch to strain after a c section. she probably has an infection and needs antibiotics, however to be on safe side, am taking her to the vets now. keep you posted and thanks for advice.