At 8 weeks all kits should be eating and drinking independently and the Dam is probably fed up with them still trying to suckle. Check her nipples, she might have mastitis. That would require treatment from a Vet.
She might be dry ( no milk left)
As long as all kits are eating and drinking independently you can remove the Dam from the litter and house her separately. It is better for the kits to remain in the familiar accommodation. It would be VERY abnormal if any kits are not eating and drinking independently and indicative of a possible health problem so a vet check would be essential.
You need to be certain of the gender of all kits. Does and Bucks need to be separated at 10-12 weeks to avoid inbreeding.
If you are in the UK the Kits need vaccinating (Nobivac Myxo-RHD Plus ) which can be done from 5 weeks of age
For neutering Bucks can be castrated as soon as their testicles descend, usually by 14 weeks. Does can be spayed from 5 months of age as long as they weigh at least 1kg. Some Vets will spay from 4 months.
Watch out for any fighting between the litter. This can occur when they approach puberty. Entire Bucks are almost guaranteed to fight unless you get lucky and get them castrated without any prior aggression being shown. It is possible, I have done it a few times and the brothers remained together for life. But usually entire Bucks need to be kept alone until they are castrated. They will remain fertile/have hormone surges for up to 6 weeks AFTER castration so any bonding attempts need to wait until 6 weeks after castration.
