Every pet owner has been repulsed by something their pet does and wondered why it happens.

The first reason? They do so because they are animals, not humans. They will breed with their sister or mother if allowed. They lick the insides of one another’s mouths, as well as yours if they get the chance. They eat feces. They will fight, kill and consume prey and people without criminal intent.

I am very fond of my dog and cat, but I do not expect them to have the higher-order thought process that humans do. I expect them to behave like animals unless they are closely monitored and directed otherwise. Even then, the best trained animals I have ever known will revert to their basic behaviors in the absence of sustained human interaction to the contrary.

My dog is bad, which means I am bad, too. She loves everyone and jumps up to lick anyone who gets their face too close. If allowed, she’ll shoot her little tongue in your mouth, too. ICK!

So why does she do so? The answer, beyond being an animal, is she is descended from wolves across about 20,000 to 30,000 years. Wolves all greet each other by jumping up and mouthing mouths. Some behaviorists suggest this might be a survival mechanism learned as pups whereby hunting wolves returning to a pack are sampled for food residue in their mouths by those who hung around the pack.

My brother once brought one of his big — and I mean big — Weimaraners to our home. It was the first time the dog been there. Within 10 seconds, he’d made his way to the kitchen and defecated on the floor. Why? Well, it was new territory for him and he felt a natural urge to mark it as his, lest the rest of the Weimaraner brethren come along and want to know why he didn’t do so.

Everyone who has an indoor/outdoor or exclusively outdoor cat has wondered why they bring home dead trophies from a hunt. For our cats over the years, it has often been limited to the gallbladder of a small rodent. Why the gallbladder? Perhaps because the concentrated bile salts inside taste bad?

Perhaps it is just a prize for you? Still others postulate that whatever a cat brings back to the domicile that is edible is to help you as a poorly fed kitten since you are not looking much like a cat. I’m not sure I buy that one.

So why do dogs eat poop? Listen, if cat poo were landmines, my dog would be the top pup for clearing a minefield. She can find that stuff quicker than you can imagine. I’ve gotten her to “leave it,” or “drop it,” but it is a task of constant vigilance.

Dogs who eat feces are exhibiting canine conspecific coprophagy. Save that last word because I once wrote an opinion piece and described an unscrupulous person as having a “coprophagic grin” on his face. Back to the dogs, there are lots of reasons why one may eat poo. Mom dogs do so to clean up around where a litter of new pups are.

Wolves and dogs evolved to be scavengers so they may be seeking additional nutrients. Most authorities say cat poo is attractive because of the fats that come through.

They may be coprophagic because of anxiety or a need to gain your attention. As always, it’s best to visit with your veterinarian about these issues but remember, we’re talking animals here, not Grandma.

Powell is the public information officer for the Washington State University College of Veterinary Medicine, which provides this column as a community service. For questions or concerns about animals you’d like to read about, email cpowell@vetmed.wsu.edu.

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