Recent studies have shown that, thanks to advances in anesthesia (the newer Isofluorane is much safer than that of olden days), male dogs suffer no ill effects from being neutered as young as 8 weeks of age. However, females spayed younger than 12 weeks showed a higher risk of developing UTIs (& recurring UTIs) & urinary incontinenece. It is recommended to wait until a female is 12 weeks of age to spay.