Generally speaking, dog and cat feces should not be used as a worm food source or in a compost heap. Both have the tendency to be difficult to work with (strong unpleasant odor etc), but even more importantly they can create health hazards for humans.
Dog feces is typically rich in fecal coliform bacteria, and can contain harmful parasites as well. Cat feces is potentially even more dangerous – especially for pregnant women and small children (those younger than 5 years old). It can contain Toxoplasma gondii, a single-celled organism that can be transmitted from a pregnant mother to her unborn child, potentially leading to brain and eye disease. It can also contain Toxocara cati, a parasitic roundworm that can cause similar problems. Cats (and dogs) that are kept exclusively indoors, are not fed raw meat etc, and are taken to the vet regularly will tend to have a much lower chance of having contaminated feces, but one should still exercise caution regardless.
Bottom-line, I would NEVER recommend adding dog/cat waste to one of your main worm beds. The health risks are too great, and it won’t likely be much fun either (who wants to smell dog poop all day long?
That being said, there are still some options for dealing with these wastes with the help of your worms, rather than tossing it in your trash or leaving it on your lawn.
You can easily create a completely separate system (well removed from your main worm farming set-up) for composting pet wastes.
What I would do is dig a deep round hole (approx. 3-4 ft deep x 2 ft across), line the bottom with a nice thick layer of shredded newspaper, shredded cardboard, or coconut coir (something carbon-rich and absorbent). Again, make sure to locate this hole a good distance away from your main worm farming area, compost heaps, gardens etc. Also make sure it is NOT located near a body of water (stream, pond etc).
You will want some sort of heavy lid over top of the hole (something a small child won’t be able to move). Even a standard black backyard composter positioned over the hole could work well (the variety that is solid plastic, not one with plastic slats and wide openings). Aside from keeping kids away, covering the waste materials will allow you to control the amount of moisture that is added.
Simply add your pet feces along with some more bedding material (any time you add feces add some bedding over top). Other materials that would work well at this point are straw and fall leaves – they are not nearly as absorbent as the materials mentioned earlier (and thus aren’t as well suited for the bottom of the pit), but they will be great for covering up any feces you add.
I definitely would NOT recommend adding the entire contents of a cat’s litter box unless you use some sort of biodegradable alternative (like newsprint pellets or wheat hull litter) – most cat litters are made of clay and you’ll just end up creating a messy clay sludge in your pit.
Adding some water periodically will be important but you definitely don’t want to go overboard, especially if you have a thick clay soil with poor drainage. Perhaps every couple times you add feces you can also add a small amount of water using a watering can.
Worms should not be added to the mix right off the bat – pet wastes will tend to give off a lot of ammonia and will not be ideal food for the worms when fresh. In fact, the best approach would be to set up two of these pits simultaneously.
Once the waste and bedding has made it about 3/4 of the way to ground level in your first you can start your second pit in exactly the same manner. After a couple weeks (without adding new feces) add a bunch of red worms to the first pit. As long as you have added enough bedding along with the feces and have kept the contents moist, conditions should be ideal for worm composting by that point.
The level of material in the first pit should decrease quite readily now that there is a population of red worms in there. Once your second pit is 3/4 full you will be able to safely add fresh feces & bedding to the first pit once again (since there will be enough of a safe habitat for the worms).
Planting ornamental trees and shrubs in the immediate vicinity of your ‘poop pits’ will allow you to take advantage of the nutritious compost you are producing. I definitely would not recommend removing the compost at any point, due to the potential health concerns I mentioned above.
Hope this helps!
Worm farming secrets newsletter updated by World of Worms