
Has ben known in my breed. Keep a careful eye on weight gain, and start offering sloppy solids as soon as eyes are open if the rate of weight gain slows.
As long as your making sure all get to feed with special attention to the smallest, and bitch is fed enough you should not have to supplement with top up milk feeds, which is best avoided unless really neccesary.
Even if Mum does them well I'd start weaning around 2 1/2 weeks to take the pressure off her, though she will still be their main food source until at least 4 weeks.