A mother cat sometimes refuses to care for particular kittens in her litter or rejects the entire litter. After helping your cat through the birthing process, observe her behavior closely to ensure that any kittens she rejects you can care for yourself. Under some circumstances, you may be able to get her to care for the rejected kittens.
Depending on the health of the kittens, a mother may reject those she feels will not thrive to ensure the survival of her other kittens. Mother cats may reject kittens with a medical issue or anatomical defect. Those cats who give birth to a large litter of six or more kittens may not be able to nurse all of the kittens, rejecting some out of necessity to feed the majority of the kittens. In addition, a mother cat suffering from illness or poor nutrition may be unable to care for her kittens, leading her to reject them.
After birth, a mother cat should begin nursing her kittens every one to two hours. The milk a mother produces after birth contains colostrum, a substance that contains antibodies to help protect the kittens from illness and give them rich nourishment. If you see that the mother ignores certain kittens, refusing to allow them to nurse, she is rejecting those kittens. Another sign of rejection is when a mother moves one or more of the kittens to a different location from the nest to isolate them. She also may hiss at the kittens or try to bite them.
A mother may reject a kitten that is cold to the touch. Place a cold kitten on a hot water bottle wrapped in a towel and massage its body to increase its circulation. Try placing a chilled kitten that you have warmed back up with its mother to see if she accepts it. A kitten increases in size daily, but if you notice a kitten not gaining weight or growing properly, the mother most likely has rejected it. Undersized or warm kittens who the mother has placed aside and refuses to nurse require bottle-feeding; she may reject the entire litter if you place them back in the nest, according to the Purrfect Companions website.
If you notice that a mother cat is refusing to nurse kittens over 4 weeks old, this is normal behavior; kittens are weaned from the mother's milk onto solid foods between 4 and 8 weeks. Do not handle kittens under 4 weeks excessively, as this may cause the mother to reject them because it removes the mother's scent. Handle them for 10 to 15 minutes at a time under the supervision of the mother cat. Take rejected kittens and the mother to a veterinarian for an exam to check for medical conditions, infections or after-birth complications as the cause of the rejection. Bottle-feed and care for rejected kittens by hand.