Along with eggs, I've used previously unopened sour cream WAY (, way) past the date and do the same as you once it's opened. Between the pasteurization of the original milk and then innoculation with good microbes, the lower moisture content and the acidity, it's not a very hospitable environment for pathogens.
Cauterization definition, to burn with a hot iron, electric current, fire, or a caustic, especially for curative purposes; treat with a cautery. See more. Dictionary.com
Neutering is a procedure to remove a male kitty's testicles. This is done through a small incision on his scrotum. It doesn't take very long, and only requires a minimal amount of anesthesia. The incision is so small that it doesn't need to be stitched back up after surgery. Once everything has healed and his fur grows back, it's hard to even tell the surgery was done.