
Only just seen this Marianne. Barbara is right that I find it normal. And even with pups just under 3oz so hardly amazons! Yes I do use a heat pad, simply because they don't retain their body heat very well when this tiny. The house also has the central heating on if the slightest chilly. I don't mean when it's this time of the year when it is turned to constant anyway. I'm a delicate hot house flower and need my heat. :-)
I've never found that the tiny tots suckle less strongly to be honest. Actually they are normally little greedy guts and they are permanently attached to a teat. When sleeping, if mum moves they have a natural reflex which says quick suck really hard now, they make sure that they stay glued on.
Some of my bitches really like the heat pad themselves and book it for 6 weeks.
Oh just thought! I do not supplement. Mum can give them far better milk than I can. It's her job to feed pups and it's my job to feed mum anything and everything she wants. I do hand feed in the whelping box as my bitches are swines to come out for food. I have to drag them out kicking and screaming for a visit to the garden.