Don't Try This at Home
I don't know a single composting expert who thinks that composting pet waste is a good idea. Don't we ask enough of earthworms as it is? You fill a vermiculture bin with worms and they are essentially your prisoners. They live their entire lives in the confines of that bin, eating whatever you serve them and churning out nutrient-rich castings without expecting so much as a thank-you.
They put up with laboratory tests in which their tails are cut off and sutured onto the heads of other worms for no other reason than to prove that it can be done. They ingest toxins at polluted sites only to be killed by a scientist who wants to measure the poison in their tissue to monitor the progress of the clean-up.
We put them on bait hooks. We let them fry on the pavement after a rainstorm.
And now we're going to ask them to eat dog shit? Really, enough is enough.
Tumbleweed, an Australian manufacturer of composters, has created a Pet Poo Converter, a worm bin marketed specifically for converting pet waste to worm castings. Why not, you might think. We use chicken and steer manure in the garden. Why not Labrador manure?
Because dogs and cats eat meat, that's why. There are harmful pathogens in their feces that make them unsafe for human contact, namely toxoplasma and cryptosporidium. There's a reason we use such an elaborate process to treat human waste, folks. Same thing applies to pet waste. You're going to be using this product in your garden, and you should expect it to be safe.
(And that's not to mention the smell and the possible ammonia levels--which can be harmful to earthworms--if urine is present.)
Tumbleweed's website says, "It is important to understand that you cannot feed the worms a mixture of diets. If the worms are offered a choice of vegetable scraps and pet poo they will choose the vegie scraps." Well, yes, I would think so!
Please, folks, don't even think about sharing the content of your litter box with the worms. They're doing good, honest work and producing a product they--and you--can be proud of. They're no more interested in eating Fido's turds than you are.