Hi my bitch is day 25 today from her first mating. She has become very withdrawn and gone off her food. Her nipples have enlarged a bit and her vulva hasn't gone back to normal size since mating. If she is pregnant would a scan be able to detect any puppies. Many thanks

Not being a fan of scanning (which isn't accurate and only confirms or otherwise a pregnancy at the time of the scan) I'm not sure when you can first scan.   But, depending on how well you 'know' your bitches, you should be able to tell she could be in whelp by the thicking of the flanks which can be seen, usually, by the end of the 4th week, going into the 5th.   And you will see the puppies moving around by week seven.   I have always seen the vulva doesn't go back to 'pre mating' size, if they are in whelp, either.

I haven't had any need to scan - we clear our slates when we do a breeding in any case so nothing has to be cancelled or arranged, and again it's not accurate enough, for me to be bothered.   I have a feeling that even I was told no, I'd still be waiting, ' just in case'.

Those here who do hang their hats on scanning, will be able to tell you when (what stage in the pregnancy) you can scan.

Day 25 is too soon for a scan. You want it either day 28 if an experienced scanner, or more than 30 days if done by most vets. I would not expect to see any physical signs at all after just 25 days. I don't see enlarged teats until  5 weeks. But a change in temperament is often the first sign in my bitches and that can be early on.

I have had a bitch scanned and confirmed in whelp by scanning this early by a vet specialising in diagnostic scanning, but a vet who is good at Palpation can do so at this stage up to about 28 days.

Most scanners want to see the bitch about 30 days from last mating, and will rescan at 35 days if negative.

Thanks everyone for the helpful advise. This is my first time so it's all new to me. Thank again