At what stage in pregnancy should you really slow down with the walks? My friends girl is on day 49.

Be guided by the bitch; she usually knows best. It's vital that the bitch is in peak physical fitness for whelping.

Yes, I agree. We just back straight out onto fields but I always take a lead with me, so if I pick the lead up and my girl wants to go out then we do, if I pick the lead up and she shows no interest then we don't, but to be honest that is usually on the day of whelping she looks forward to a short walk even when she all but waddles, the last thing you want is for a bitch to spend too much time lazing around with no exercise they need to keep fit, so tell your friend to go by her girl.

Walk her in safe places where other dogs are not going to jump all over her or stress her and walk at her pace. ;-)

mine was running (or more like trotting lol) right up until the day before she whelped... She wanted to get back out about a week after pups were born, but it was just short 15 mins here and there and slowly built back up again.