The survival rate of microinjected eggs implanted into the pseudopregnant recipient female varies tremendously from 0 to 50%, resulting in abnormally small or large litters. In the former case, the few eggs that do develop tend to be overnourished. Fetuses grow too large to be delivered normally and risk dying in utero. If pregnancy proceeds for 2-3 d beyond the normal gestation period of 19-21 d, the pups can be rescued by Caesarean section and fostering. It may also be necessary to foster pups born normally to a mother that dies unexpectedly or pups in a large litter that are not fed sufficiently.
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