I wonder if I could ask some advice please.  My pups are now 10 days old and in my litter of 8 (med sized gundog breed) there is one pup that was born a few grams lighter than the others (6g between her and the next smallest). Came out with a greenish placenta and without her sack.  She was fine at birth fed and squeaked straightaway and has doubled her birth weight (like all the others) in 8 days. However the amount she puts on each day is much less than the others and she is still considerably smaller and thinner, so for example she now weighs 663g and all her brothers and sisters are now weighing between 750g to nearly 900g. When they are all asleep she is very much the tiny one. The sibling that weighed only 6g more than her at birth now weighs 750g) I am putting her on the nipple every time I can as well as during the night and making sure she is at the back, she seems to suck well although tires easily and falls asleep before everyone else or is easily pushed off by her bigger siblings.  I am spending all my time making sure she is feeding and not being pushed off.  She is crawling around the same as the others, is warm and sleeps in a pile with everyone else.

At what point would you give a few extra feeds via whelpi or something or would you leave well alone?  I am just really concerned that her bigger brothers and sisters will really overtake her soon as they are big and chunky and despite my best efforts she wont be getting enough milk.  The whelping box is in a secluded corner of my kitchen so I am literally seconds away to keep an eye on her.  My first thoughts are not to interfere and just to keep replacing her to the nipple, however my gut instinct is that I ought to step in.  She has been checked out by a vet for things like cleft palette as Mum had a bit of a placenta retained and they all spent a couple of hours at the vet within a few hours of birth.

What would you do?

She cannot gain the same rate as the bigger pups, but is she gaining what they were at her weight.  Just make sure that she gets extra feeds from Mum when the others are asleep or she has left them put pup on a towel next to Mum for additional feeds. 

This pup will be unable to take on as much food as the others can, so needs more opportunities to feed.

I weigh in ounces so would never have noticed a 6g difference in weights as relevant, usually going in half ounces.

As soon as their eyes are open you can start offering puppy food as a porridge, I generally start mine at 18 days, but where weight gain of the litter was levelling out overall, I have started as early as 12 days.

You will probably find her catching up with extra time on Mum and when you start weaning in a week they will really start to pile it on including the little one.

I had a tiny bitch with 4 big fat brothers.

I just helped get her place and to draw enough milk and she grew and caught up.
When the siblings are so much bigger the milk flow is sometimes too much and too fast for tiny ones and they get flooded, watch for that and be quick to unpop the little one after her fill.