Shirley emailed me with this question...
I have three cats and one dog. I feed all of them Iams food, as well as pet-intended treats, but not to excess. I also have two cat litter boxes that are cleaned each day. You probably see where this is going ;) . Why, in the name of all that’s not gross does Star-the-dog insist on snacking from the litter box?
Everyone is at a healthy weight and has no medical problems for which
they’re being treated. Is it just a case of “she’s a dog, and that’s
what dogs do.”?
This is actually a very common situation and one many pet owners face. That includes me! The litter boxes are in our laundry room and we keep a baby gate in the doorway to keep our dogs out of the "kitty crunchies".
One of the first things we have to remember is that a dog's palate is different than ours. Things that make us gag just thinking about them are absolutely delicious to a dog. Their taste buds are oriented to things like raw flesh and organ meat, so while few of us would dream of dining on raw intestines and liver, dogs are designed to be drawn to these things. They are going to find many things tasty that we are repelled by.
Feces contain quite a lot of ingredients. Besides the obvious waste, there will sometimes be food particles that pass through without being completely digested (something we've all witnessed in our own toilets with corn kernels). Such undigested or partially digested food becomes more prominent if a pet has intestinal absorption issues or enzyme deficiencies, or if the pet is being fed more than their body needs. Certain ingredients may also give a stronger odor as they are passing through, and these odors can be attractive to a dog. If a dog is hungry or the odors are "good" enough, they will take to snacking on other animals' feces.
Additionally, feces are used for scent marking. Dogs and cats have glands on either side of their anus that produce very malodorous secretions and are normally expressed onto the stool during a bowel movement. Taste and smell are very closely connected, so licking or chewing something with a scent mark can be a way of getting a more detailed examination of the substance.
There are several ways to try and curtail this behavior. First is to do something similar to what I do and keep the dog from having access to the feces. Making sure there are no health problems and you aren't over-feeding is the next step, and it sounds like you have both of these situations covered, Shirley. Lastly there are products you can get from your vet that are food additives which will make the feces less appealing.
In the end, though, the short answer is very much along the lines of "she's a dog and that's what dogs do."