I think the major problem with animal faeces is that they can contain
all sorts of parasites and pathogens that can affect human beings, some
of them quite tragically. (Toxoplasmosis and leptospirosis spring to
mind... both can cause serious birth defects if passed from a pregnant
woman to her foetus). There's also a smorgasbord of worms and flukes
that can exist in various forms in poo and be transmitted to you through
direct contact.

AFAIK, sewage treatment is specific for human poo and cannot break down
the various animal poos. Dog poo, for example, is a true turd (I'm not
joking: that's the correct name for it!) and has a laminating outer
layer which protects the dog's intestines from mechanical damage as
bones and sharp bits of it's 'prey' pass through. This layer, once
hardened, resists breakdown of most treatments and can help to keep
parasitic larvae alive inside the turd, even through some pretty severe
chemical baths. (If my Mum knew I was writing this, she'd have a
coronary! LOL!)

Cat poo has similar properties, although not entirely the same. The hair
component in cat poo resists breakdown as well and would probably
prevent the poo from succumbing to the usual methods in treatment works.
AFAIK, human poo is basically water soluble and that's the main
difference...

I do *not* have an unhealthy fixation on poo! (Just in case you were
wondering) I studied animal poo as part of my Zoology course and - well
- it stuck! ;-

--
Trish {|:-}
Newcastle, Australia