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While spaying is traditionally recommended for kitties between 4 and 6 months of age, spaying as young as 8 weeks old is considered safe, according to Cat Channel. Many animal shelters actually spay kitties prior to adopting them out at this age.
The youngest a kitty should be before she's spayed is 8 weeks old. Little ones this young need to be at least 2.2 pounds before surgery, recommends the Ohio Alleycat Resource. Young kittens tend to bounce back after surgery pretty quickly.