Why Dogs Eat Dirt: Healthy Adaptive Behavior to Toxins in Your Backyard
When my dogs started eating dirt in the backyard last summer, I wondered why they suddenly craved clay. Wasn't it harmful to them? Was it a symptom of a nutritional deficiency or parasites? My research on the subject turned up some surprising theories on geophagia, which is the clinical term for eating clay. (Scroll down for videos of humans and dogs engaged in serious serious geophagia).
Pica: A Southern Tradition
As it turns out, here in the South, there is a long tradition of human clay-eating. Aficionados of clay claim that the flavor is a nice mix of bitter and sour. Some augment this taste sensation by toasting the soil and adding salt and vinegar to the baked earth. Southerners with a family tradition of geophagia will even ship bags of soil from favorite dig sites in the hometown area to their displaced relatives up North.
While geophagia has been practiced on all continents at various times in history, clay-eating by humans in the United States carries a stigma. In fact, the DSM IV categorizes pica as an eating disorder, since excessive clay eating can cause intestinal blockages. Dog owners also cringe to see their pets wolfing down soil in the backyard. However, researchers have found that not only dogs and humans engage in geophagia, but cats, parrots, buffalo, deer, fruit bats, other primates, in addition to a host of other mammals, engage in clay-eating at various times in their lifecycles.
Woman Eating Dirt and Loving It, Earthworms Included
3 Theories to Explain Dirt-Eating
1. An Attempt to Counteract a Nutritional Deficiency
Pica, the craving to consume something other than food, is typically associated with lower-income children and pregnant women in our society. In fact, geophagia in expectant mothers in Nigeria has been relied on for centuries as an indicator of pregnancy.
Given that growing children and expectant mothers have considerably greater nutritional needs, it has long been assumed that pica evidenced a nutritional deficiency. For example, expectant mothers in other areas of Africa, where calcium is readily available do not resort to clay eating as their Nigerian counterparts do. Depending on your area, soil may contain nutrients not readily available in the local human and canine diets. Iron, calcium and sodium are found in many areas where clay abounds.
2. Some Clay Has Medicinal Properties
Kaolin, a white clay found here in Georgia, has the ability to stop diarrhea and stomach upset. It is so effective that it has been used in manufacture of Kaopectate, Rolaids, Maalox and Mylanta. The anti-nausea properties of clay have been cited as a possible reason pregnant women tend to begin or increase their soil consumption. Some researchers theorize that clay soothes the digestive tract and counteracts morning sickness, hence the expectant mothers’ clay diets. But other researchers have begun looking at the origins of morning sickness as key piece of the puzzle of clay cravings.
3. An Adaptive Behavior to Bind Toxins
Clay has the additional, extraordinary ability to bind itself to toxins and help eliminate them from the system unabsorbed. Clay has long been used in health spas and mud baths for external detoxification, and early Greek and Eastern medical practitioners used it internally to detoxify patients. In fact, clay is still in use as a condiment on bitter, slightly toxic potatoes in South America and New Mexico. The toasted clay is sprinkled onto the potato dish where it will bind to the toxins in the potato, allowing the potato dish to become nutritious and nontoxic.
Following this line of reasoning, researchers have suggested that as the expectant mother’s body draws on its internal resources to support the growing baby, it also draws out stored toxins stored in body fat. The toxins then cause nausea, the body’s attempt to rid the system of the toxins by vomiting. Cravings for clay and the subsequent consumption of the clay effectively eliminates the toxins from the system. Additionally, much in the same way the South Americans used dirt to detoxify their potatoes, clay consumption may also serve to bind food born bacteria and viruses that would be harmful to the mother and developing fetus. It appears that clay eating is frequently an adaptive behavior, and perhaps not always an eating disorder, as it has been characterized in the DSM IV.
German Shepherd Dog Eats Dirt and Loves it!
Why Do Dogs Eat Dirt?
Just like humans and other mammals, dogs may eat dirt for several reasons. They may be seeking additional nutrients, need a sedative for intestinal upset or simply enjoy the flavor. It is interesting to note that soil frequently harbors parasites, and clay eating could create a cycle of parasitic infection. The dog or human eats the soil to sooth its intestines and simultaneously infects itself with parasites (whipworms, hookworms and roundworms can be found in soil). If your dog is eating dirt, it’s a good idea to get a fecal exam done to eliminate parasites as the possible cause for soil eating. Of greater concern is the possibility of toxicity in the dog’s environment as a stimulus for dirt-eating.
In trying to understand the cause of my dog’s clay eating, I reviewed the geophagia theories with an eye to my pet’s situation. None of them was pregnant, and fecal tests showed no parasites. They are very particular about the clay they eat. Not any old dirt will do; the clay they eat comes from one small hole in the back yard. Interestingly, their clay consumption, like that of many other dogs that appear in research, is seasonal. Their dirt eating begins in early spring and increases into midsummer. By fall, the clay consumption tapers off and through winter there is minimal interest in the clay.
We live in a suburban environment, where neighbors have services that routinely apply pesticides and fertilizer to the lawns throughout the neighborhood from spring until early fall, which appears to coincide with my dogs geophagia. The National Cancer Institute has linked commercial weed killers and pesticides to the increase of certain deadly cancers in canines such as hemangiosarcoma. It could be that my dogs, and other clay eaters in urban and suburban environments, are absorbing toxins from walks through their neighborhood and runoff into their yards. They then resort to clay eating to detoxify in the spring and summer months. Consuming clay under these circumstances would be an adaptive behavior, and one that I hope is successful for all canine clay eaters. Certainly if your dog has recently begun clay eating, investigate any changes you may have made with floor cleansers or in your yard maintenance. As for your neighbor, don’t begrudge her a spoonful or two of soil to finish off the day or spice up her potatoes.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.