Leah and Gwen, I think you are right about the euthanasia. It will be necessary, certainly until/if spaying and neutering programs are begun and have an effect, and most likely well beyond. It is sad to have to ponder that as anyone who has ever been blessed with a sweet and loyal pooch will know. I've had several.
This is probably taking
permaculture waaay too far, and not even Mollison, to the best of my knowledge, has had the nerve to tackle this, but as a society, sooner or later, we're going to have to get over our penchant for burying people and pets in graveyards rather than returning them to the fields to nourish the crops.
I remember Lee Hays, one of The Weavers -- renowned folk singers -- specified in his will that he wanted to be cremated and have his ashes spread on the compost pile, and that's exactly what happened. I always thought this was the right spirit.
And obviously an animal shelter with a euthanasia program is going to have a lot of animal carcasses to deal with. How do you use them as input? Do you treat them as a kind of
hugelkultur and plant over them? What are the safety considerations?
Slightly off topic, there's a must-see/read play by Sam Shepard called, Buried Child, in which a desperately bored wife of an alcoholic couch-potato farmer has either an incestuous encounter with her autistic son or an affair with the town preacher, depending on how you interpret things. Anyway, the liaison produces a baby, which they quietly bury, at birth, in the garden. No one finds out, but the following spring, the garden starts producing enormous, beautiful, luscious, juicy vegetables and fruits that just amazes the neighbors and starts people wondering what the hell they used as fertilizer. And, of course, the embarrassed woman has no answers. The play won the Pulitzer Prize in the Eighties, deservedly so.