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
A spay is actually an ovariohysterectomy; the uterus, ovaries and the two cervices of the rabbit are surgically removed. A castration, or orchidectomy is the removal of the testicles. Both spaying and castration can be referred to as neutering, although many people use the word neutering when referring to only male animals.