If your pooch regularly snacks on dirt, paper or even feces, he’s doing it for a reason.

Whether that means mineral deficiencies, anxiety, or even boredom. Our dogs, despite all the changes that domestication has wrought, still enjoy some wolf-like activities, according to Kristi Benson, a dog trainer who holds a Certificate in Training and Counseling (CTC) and is a fan of skijoring (cross-country skiing attached to a dog). “And we do know that chewing is good for dogs for a few reasons—it is a healthy exercise for their jaws, it can help keep their teeth clean as part of a good dental hygiene program, and it is a mentally enriching boredom-buster,” Benson says. So if your dog is chewing non-food items, the first step is understanding why before you work on changing it. Here are 4 reasons why Fido is doing just that.

The “Stuff” Looks or Smells Like Food

Although we can’t ask dogs why they’re eating a particular toy, chances are that the toy just feels or smells like food to Fido. This is especially true of puzzle toys which you normally stuff with treats. If we imagine the dog’s ancestor, the wolf, they would certainly find chewing bones to access marrow (rich in fat and nutrients) to be a good plan, according to Benson. “Dogs seem to have transferred this ‘get the marrow out’ behavior to non-food toys,” says Benson. In addition, Benson points out that dogs also have an “eat first, ask questions about palatability later” approach to life. “If something drops nearby and there’s a chance it’s food, they’ll gobble it up,” says Benson. “And ripping apart a small prey item looks pretty similar to how dogs rip apart their stuffed toys, if you think about it.”

He's Having Tummy Trouble

Dogs also eat grass or similar vegetation when they are feeling the need to vomit, according to Benson. “One more reason to avoid harmful chemicals on your lawn,” she adds.

Nutritional Deficiencies

Pica (the eating of non-food items) is often connected to nutritional deficiencies—and what your dog is eating could be an indication of what he’s missing. Because pica can be linked to malnutrition, malabsorption or even an unbalanced diet, figuring out what’s missing in your pet’s diet is essential to solving the problem. For example, dogs who eat dirt often have a mineral deficiency and are trying to find somewhere the nutrients they’re missing in their diets.

Boredom or Stress

Dogs who are feeling upset can chew to calm themselves down—or at least, that’s what it looks like to us humans, according to Benson. “Dogs who are experiencing separation anxiety—which is a panic attack that happens when dogs are left alone—will often chew and scratch exit points of their homes such as door frames,” Benson says. “These dogs are likely trying to escape and reunite with their family.” Owners who are unsure if their dogs are chewing for fun (which can be helped by having dogs redirect their joyful and healthy chewing behavior towards appropriate chew items) or out of anxiety (which can be helped through a program of getting the dog used to longer and longer absences) should take a video of the first ten minutes after they leave, and watch for body language cues, says Benson.

Stopping the Behavior

Before you do anything else, talk to your veterinarian to see if there’s a health issue lurking underneath that could be causing the problem. “Some behaviors which look compulsive have solely medical underpinnings, and your medical team can identify this,” says Benson. “If there is a behavioral component, medication can still really help.” Once you’ve addressed any potential health issues, the next step is to work with your dog at home. “You’ll train your dog to do an alternate behaviour and ensure that anything which might produce conflict or anxiety is removed from your dog’s life,” Benson says. “You’ll also give your dog a lot more to do: more exercise, and more mentally enriching toys.” Training can work wonders, and often dogs who are anxious can improve drastically once the focus is put somewhere else rather than the obsessive behavior.