The causes could be anything from mouths not being properly formed to cleft pallet. You will have to take over the feedings using a bottle, dropper, syringe, or a pipette. Try rubbing honey onto their gums and smearing some warm milk around their mouths.
Hi DianeApril. I am sorry to hear that you have a serious problem with recurrent losses of litters from the same mum. Are the little ones latching at all? There is obviously something very wrong with your cat for her not to be able to feed the kittens. She needs to be seen urgently by vet and you should be hand feeding the kittens without delay. Is mum keeping them warm? Have you read the articles by Columbine (Post N°4)?
Please let us know what is happening. Best wishes.
HAD you done your outmost to handraise them? And they died anyway?? If so, they are goners, nothing more to do save spaying momma and daddy, as earlier said..
Hadnt you not handraised - and there is still any alive: Do so asap!!! The chances are good!
Return back for more advices if you need. As now, its not entirely clear in which situation you are, what you can and are willing to do.
IF handraising helps - which it normally does if you are vigorous enough - there is perhaps not the same hurry to spay, but its probably the best anyway even if they are purebreds of decent lineage... You dont want to risk bad genes to spread further into next generations.
Re handraising. Its not easy, much work and little sleep, but can be done. Its usually easier to handraise orphans than weak sickly kittens, but also the weak sickly kittens are worth a good try. If they make the childhood, they usually become healthy adults.
As a dramatical example for what can be done by a dedicated owner / rescuer.
There was this swedish Russian blue breeder, whose 2 RB females got litters almost simultaneously. Unusually big litter for RB: one got 11(!) kittens, the other 6. Tragedy struck, the 11-mom died shortly after the birth.
Owner handraised the herd together with the 6-momma. but the 6 momma got sick too after a while - washing 17 kittens become too much for her system....
So the owner had to handraise simultaneously 17 kittens AND a sick momma. She managed everyone!
Problem with that? I was careless enough not to write down what for home-made kitten glop she used because she hadnt access to kmr nor goats milk... It looked amateurish, but you dont quarrell with success: if it worked that splendidly as it did, it must be as good as many modern krm...
If it is the same mom, I would suggest spaying her and possibly the dad too. It could be genetic issues, and some cats just do not want to be a mom so they do not take care of them. If a mom knows her kittens won't make it, she will just abandon them to die. I fostered a pregnant cat, she gave birth to 4 but one had a really traumatic birth, was breached and it took over a minute to birth. I tried tapping on his chest to get all the fluid out, but sadly he still didn't make it. She refused to nurse him a day later (she moved all her other kittens under the desk but moved him away from the others), and he refused to nurse at all and passed away. Fading kitten syndrome is heart breaking.