I start mine slow, maybe 1/4 teaspoon and work up to a teaspoon for an adult, and can be applied topically, and on the coat if it tends to be dry.
Many members here follow Dr Dodd's vaccine protocol; see links at the bottom of this page:
http://www.yorkietalk.com/forums/die...-overview.html
Age to neuter: Hot debate topic: I like later than earlier, 12-18 months, definitely after the growth plates have closed determined by xray.