did the vet weigh her on the same scale? When I first had remy she lost weight between visits when I was taking her in for shots... I asked how could that be?? The vet checked the records and then took her into the other room and sure enough she had gained an ounce...
He said there could be a few ounce difference per scale.. and with a biger dog it really would not matter or even be noticable (like my Bailey -- he weights 26 lbs
2 or 3 ounces would not make a difference)