According to this PRI thread, horse dewormers don't kill earthworms

I wasn't sure where to put this but I think it's really interesting: I've always been a bit that even the fresh horse manure I've seen is full of worms as I've always assumed the 'under two weeks and they're dead' scenario was accurate...
Earthworms are a different species from intestinal worms though
Interesting.
Of course, none of this is making any kind of case for anyone buying and using poisons, but I'm a big fan of keeping nutrients out of the waste stream, so this kind of thing makes me happy!

Does it actually say anywhere which chemical was used in the 'worming mix'? I'm pretty sure there are several, rather distinct families of chemicals that are used, and they're bound to have different effects.

The guy doing the experiment quotes using 'Abamecitin 4mg/g, Morantel Tartrate 167mg/g.'
There's a link to an article with further info, but I can't access it.

There are several natural dewormers available.

I have talked with a couple horse people who claim this has worked for them:
http://www.verm-xusa.com/index.php

They make versions for various other animals.
This is what's in the 3 forms of horse 'medicine':

Powder ingredients include:
Allium Sativum (Garlic), Mentha Piperits (Peppermint),
Thymus Vulgaris (Common Thyme), Cinnamomum Zelandicum (Cinnamon),
Picrasma Excelsa (Quassia), Foeniculum Vulgare (Fennel),
Gallium Aperine (Cleavers), Urtica Dioica (Nettle),
Ulmus Fulva (Slippery Elm), Inula Helenium (Elecampane.)

Pellets ingredients include:
Allium Sativum (Garlic), Mentha Piperita (Peppermint),
Thymus Vulgaris (Common Thyme), Cinnamomum Zelandicum (Cinnamon),
Picrasma Excelsa (Quassia), Foeniculum Vulgare (Fennel),
Gallium Aperine (Cleavers), Urtica Dioica (Nettle),
Ulmus Fulva (Slippery Elm), Inula Helenium (Elecampane),
aniseed, micronised sugar beet pulp, seaweed meal,
dicalcium phosphate, molasses, equine anti-oxidant (Vitamin C.)

Liquid ingredients include:
Allium Sativum (Garlic), Mentha Piperits (Peppermint),
Thymus Vulgaris (Common Thyme), Cinnamomum Zelandicum (Cinnamon),
Picrasma Excelsa (Quassia), Foeniculum Vulgare (Fennel),
Gallium Aperine (Cleavers), Urtica Dioica (Nettle),
Ulmus Fulva (Slippery Elm), Inula Helenium (Elecampane.)

Most of those ingredients can either be grown at home, or easily purchased in bulk.