What Should Your Dog Eat?

Research on wild canids can help inform dietary planning for dogs.

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by CJ Puotinen

Few topics excite the passions of dog lovers as much as food. Should dogs eat meat? Bones? Fruits? Vegetables? Grains? Dairy? Should their food be commercially prepared? Home-prepared? Raw? Cooked? Fresh? Frozen? Should dogs eat what people eat? What dogs in the wild eat? Whatever the choice, is it safe? Is it dangerous?

For thousands of years, domesticated dogs ate whatever their humans fed them plus whatever they could find on their own. No one worried about fat/protein ratios, the role of carbohydrates, or how much calcium is too much.

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For help in planning the ideal canine menu, some turn to canine species in the wild, especially wolves. But even here there is confusion and misinformation. What exactly do wolves eat?

To find out, Melinda Miller, who consults to veterinarians, pet supply stores, pet food companies, and the Wolf Conservation Center of South Salem, New York, invited one of the world’s most respected experts on the wolf, David Mech, Ph.D., to present a seminar about what wolves eat.

Since 1958, Dr. Mech (pronounced Meech) has studied wolves, first on Isle Royale in Lake Superior in Minnesota, then in Canada, Italy, Alaska, and Yellowstone National Park. A founding board member of the International Wolf Center in Ely, Minnesota, he is an internationally recognized expert on wolf ecology and behavior, predator-prey relations, and wolf population regulation. Mech’s latest book, coedited with Luigi Boitani and published in November 2003, is the encyclopedic and definitive Wolves: Behavior, Ecology, and Conservation.

Dr. Mech has been a senior research scientist for the U.S. Department of the Interior since 1970 and is an adjunct professor at the University of Minnesota. His research in Denali National Park in Alaska measured the interactions between wolves, caribou, moose, and Dall sheep. On Ellesmere Island in Canada’s Northwest Territories, which is so remote that its wolves are unusually tame, he documents the interactions of pack members and their pups around their den, plus wolf interactions with musk-oxen and Arctic hares. His research in Yellowstone National Park involves the interactions of wolves with their prey.

All of Dr. Mech’s research involves the gray wolf, Canis lupus. Gray wolves live throughout Europe, Asia, and North America, and it was from this species of wolf that the dog was domesticated.

On September 25, 2004, Dr. Mech presented a “what wolves eat” seminar in New York. It was attended by about 100 people, some of whom had traveled from New Zealand, Denmark, Quebec, Ontario, Texas, California, and the Midwest.

No consensus yet
Dr. Mech began his seminar by asking the audience which animal on the planet has been most researched with regard to health and diet. The answer? Human beings. But despite decades of intense study, scientists have yet to prove that any one diet is ideal.

“If science doesn’t have definite answers regarding human health,” said Dr. Mech, “it certainly doesn’t have them regarding dogs and wolves. There is simply too much that we don’t know. In addition, dogs were domesticated from wolves somewhere between 13,000 and 100,000 years ago, so their diets should not necessarily be the same.”

What scientists do know about wolves, he said, is that they are opportunistic omnivores. Left to their own devices, they will eat whatever they can whenever they can.

“This varies by location, season, and conditions,” he explained, “so wolves in one place may have a radically different diet from wolves in another. Their preference is freshly killed meat, but when that’s not available, they’ll eat anything that could remotely be considered edible.

“For example, there are few prey animals in Italy or Israel. Most people don’t even know that wolves live in those countries, but they do, and they eat whatever humans throw away. In Italy, there are about 500 wolves and around 500,000 feral dogs, and they have the same basic diet – whatever they can scrounge from garbage cans and local dumps, as well as whatever livestock they can kill.”

In the wild, says Dr. Mech, wolves hunt live prey. In British Columbia, where game is abundant, that includes moose, bison, wild hare, two types of deer, goats, mountain sheep, elk, caribou, and assorted small animals. In other locations, there may be only a single prey species.

“Any variety is provided by circumstances, not by conscious effort, and some wolves have thrived for decades or even hundreds of years on a monotonous diet of one or two prey animals,” said Dr. Mech. “Yellowstone’s wolves are at the high end of the wolf prosperity scale, for elk are so abundant in the park that wolves eat whenever they’re hungry. Wolves in other areas go through periods of feast and famine.”

The wolves’ work day begins in the early evening, and they will typically hunt all night, then sleep from mid-morning to late afternoon. If fully fed, they may sleep for 12 hours or more. If hungry, wolves hunt all day, often traveling 15 to 30 miles or more in search of prey. Although they usually hunt in packs, single wolves acting alone have been recorded killing all of the wolf’s large prey, including moose, bison, and musk-oxen.

What’s for dinner?
What does the average adult wolf eat? That’s hard to say because wolves are difficult to observe. When fitted with radio transmitter collars and tracked by aircraft, at least a few wolves can be monitored. “We have a good idea of what those wolves eat during winter months because they’re easy to find when there’s snow on the ground,” Dr. Mech explained. “Assuming there is sufficient game, they eat an average of two to ten pounds of meat per wolf per day. In summer, no one knows, but I expect the totals are similar.”

Those figures are averages, said Dr. Mech, because wolves eat as much as possible at every opportunity. An 80-pound wolf can eat 22 pounds of meat in one sitting. When game is scarce, wolves can go for weeks, even months without eating. If sufficiently fat at the outset, a wolf can fast for up to six months.

According to Dr. Mech, wolves that live in areas populated by large prey (such as elk or caribou) kill mostly old, maimed, sick, or very young animals, such as newborn calves. “I wouldn’t say that a wolf could never kill a healthy adult. But it’s more likely that an adult animal that appears healthy and is brought down by a wolf is not as healthy as other animals in the herd. It may have been deaf, for example, or had a malnourished grandmother. Starvation is a hazard that all animals face, and malnutrition affects two or more generations.”

Wolves that hunt large prey have to be careful because they risk their lives every time they attack. “Elk, moose, and other large animals can and do kill wolves,” he said. “All it takes is a well-placed kick. One of the most interesting findings of our research was the very low percentage of successful wolf attacks. You think of wolves as killing machines, and they are, but wolves may chase a hundred or more prey animals before they succeed in bringing one down. That’s why it makes sense for wolves to study the herds, watching for anything out of the ordinary – an elk that doesn’t hold his head high, for example, or one with a limp.”

These shopping expeditions were easy to see in the videos Dr. Mech showed of Yellowstone wolves trotting through elk herds. From time to time they would chase an elk, testing the animal’s strength and resilience, and when they chose a target, the animal was easy to spot, for its posture and gait didn’t match that of the rest of the herd.

Much has been made of wolves’ tendency to kill more than they can consume, but this “surplus killing,” as it is called, is not as wasteful as it first appears.

“Wolves can’t eat more than their stomachs can hold,” explained Dr. Mech, “but they store the excess by burying it in a cache, a hole in the ground, for later consumption. The contents of a cache can be half a calf, the leg or bones of an adult elk, or even regurgitated meat. The cache is usually some distance from the kill, up to a mile or more away. When game is scarce, cached food will keep a pack alive. I’m convinced that wolves remember where they cache their food because I’ve seen them come back as much as a year later and walk without hesitation to the exact location.”

Wolves also regurgitate to feed their young and, in the case of breeding males, to feed their mates.

“Alpha” is out

Dr. Mech no longer uses the term “Alpha” to describe the dominant male and female; rather, he describes them as the breeding pair. “The family structure of wolves is much like our own,” he explained. “The whole business of Alpha wolves came about because the first wolf researchers didn’t understand wolf families, and they put unrelated wolves from different locations together. While the wolves sorted out who was in charge, the researchers concluded that every wolf pack had an ongoing fight for dominance, hence the so-called Alpha, Beta, and Omega wolves. That’s just not how it works.

“In the wild, a pack is a family. A breeding pair has a litter of pups, and the following year, they have another. Now the pack consists of two parents, who are in charge of things, plus yearlings, who are one year old, and infant pups. The following year, the pack is older and larger, with two-year-olds, yearlings, and pups. By the time they are three or four years old, most young wolves have dispersed, gone out to start their own families.”

Dr. Mech added that in a wolf pack, all of the parents’ energy and resources are focused on reproduction. “The male helps feed his mate through the winter to keep her in good reproductive health,” he said. “Both parents feed the infants, and if prey is abundant, older offspring may do so as well. Pups typically nurse for one to four minutes every three hours, and they’re weaned at seven to nine weeks.”

The first solid food that wolf pups eat is regurgitated meat, which is introduced at about three weeks. As they get older, this is supplemented by fresh meat and bones that the other family members carry to the den. At eight weeks, the pups are moved from the den to a rendezvous site, where they wait while the older wolves hunt. Eventually, at around four to five months, they begin following the adults from the rendezvous site and feed on prey where it is killed.

Preferred cuts
What parts of their prey do wolves typically consume, and in what order?

“That depends,” said Dr. Mech. “They’ll eat almost anything, but their preference is for fresh rather than frozen meat and for internal organs before anything else. The first choice goes to the wolf in charge of the kill, which is almost always the breeding male or his mate. They are the largest and most experienced hunters. They will typically rip the abdomen open to reach the liver and other organs.”

Despite what many “raw feeders” claim, Dr. Mech said the wolves he has observed do not eat the digestive tract contents of their prey. “They will remove the guts and shake them a few times to get rid of whatever they contain, and they’ll eat the rumen from around the contents. This isn’t to say that they won’t swallow some of it. They’re not washing it out; they’re just trying to remove as much of the predigested greens and other stomach contents as possible.”

In contrast, the organs themselves – the liver, heart, and guts – these are prized, said Dr. Mech. So is fat, which is hard to come by in the wild. “Wolves usually catch the weakest, least healthy animals. We have measured the fat content of Yellowstone elk killed by wolves, and it’s low. My best guess for wolves in general is that less than five percent of their diet is fat,” said Dr. Mech.

“If they’re really hungry, the wolves will eat everything – organs, bones, skin, fur, whatever’s there – as quickly as possible. If they’re generally well fed, they’ll eat the internal organs and choice meats first, then rest and come back later for more. They won’t eat antlers, very large bones, or the tooth rows of adult prey.”

As far as bones are concerned, Dr. Mech said, “Wolves eat all of the other bones, everything they can crack open. Some wolves succeed in breaking the skull to eat the brains. Skull bones are hard, though, and this is where many wolves injure their teeth. If the prey is small, like a mouse or bird, the wolf may swallow it whole.”

A pack of 10 to 15 wolves makes short work of its prey, even animals as large as moose, said Dr. Mech. “They work from the inside out, then after sating themselves rest a few hours and eat again. The next day, they eat the remaining meat, which in winter is frozen, as well as the hide, and there is always recreational bone chewing. By the third day, they pull the skeleton apart. They may leave the lower legs and hooves or cache them. If they leave the leftovers, they may return for them, or a scavenging lone wolf may find them.”

In spring and fall, other animals such as beaver may be available, or the wolves may find birds’ eggs. “Wolves would eat eggs year round if they could find them,” said Dr. Mech. “but they’re a seasonal item, like berries. Wolves do eat fruits and nuts and grass on occasion, but meat is their primary food. Their diet is almost all protein with some fat. I estimate that vegetation makes up less than one percent of the food of wolves worldwide. They simply didn’t evolve to eat vegetables.

“A lot of people assume that wolves eat large quantities of hair and fur,” he continued. “Well, they do, but if you’re judging by a wolf’s fecal matter, the percentage of hair, hide, and fur seems larger than it really is. That’s because wolves digest meat first, and they do an excellent job of it. The small amount of fecal matter produced by meat shoots out of them as a liquid. It’s not technically diarrhea, but it’s a very loose stool, and that’s healthy and normal. Then there are longer-lasting stools that are solid and that contain hair, hide, teeth, and bone residue that looks white and chalky.”

Different life-stage diets?
When pregnant and nursing, the female wolf eats the same foods as usual, just more of them. “In most cases, she’s out hunting and traveling with the pack until a couple of days before whelping,” said Dr. Mech. “Most have litters of five to six pups, with larger litters in more temperate climates where game is more abundant, and smaller litters in extreme conditions or when game is scarce.”

Dr. Mech said that wolf pups get their permanent teeth at around six months, which is when they stop receiving preferential treatment. Physically mature at 12 to 14 months, most wolves begin reproducing at age two to four years.

In Minnesota, where Dr. Mech has kept population statistics since 1968, about one wolf in every 500 lives to be 10 years old. “Once a wolf reaches age six or seven, it’s a little past its prime,” he said. “That would be comparable to a 40-year-old human. An elderly wolf is 10, 11, or 12 years old. Most wolves in the wild live around five years, but captive wolves can live to be 17.”

It’s not their diet that shortens the lives of most wild wolves; there are many causes of wolf mortality, says Dr. Mech. Wolves kill each other in territorial disputes. If there’s too much snow on the ground, prey animals can’t find the food they need, so their population goes down, and when there isn’t sufficient prey, the wolves starve. As mentioned earlier, wolves are also killed or injured by their prey, and an injured wolf is at a serious disadvantage. By far the greatest risk to wolves, though, is human exploitation.

When asked about tooth and gum health, Dr. Mech said that wolves, despite the tooth wear that comes with a lifetime of bone chewing, have strong, healthy teeth with no decay, abscesses, or gum disease that he has seen, and no other problems except for occasional injuries that break teeth. Most older wolves have a broken tooth, but it doesn’t slow them down.

According to Dr. Mech, wolves may carry internal parasites, but those parasites seldom have a detrimental effect until the wolf becomes elderly or is weakened by malnutrition. “The presence of internal parasites is not an accurate health indicator,” he said.

The key to a healthy wolf population, Dr. Mech concluded, is abundant prey. When there’s enough food, wolves reproduce, raise healthy pups, maintain a strong pack, and enjoy the social benefits of a large, active family. In return, they strengthen herds of animals by culling the weak, injured, or diseased, and play an important role in our wilderness ecology.

Some describe wild wolves as sickly creatures, infested with parasites and leading a miserable existence. Because of starvation or the stresses of human intervention, some wolves may fit that description, but to imply that all wolves in the wild are frail and diseased is the grossest misrepresentation. When wolves live in the conditions in which they evolved, on large tracts of land with large prey to hunt, these ancestors of the modern dog are among the earth’s fittest, most powerful, most intelligent, vital, healthy animals. Their strong social bonds and rich family life have fascinated humans for millennia. Their howls speak to us, though in a language few can fully understand.

Dr. David Mech’s lifetime of wolf research offers an extraordinary glimpse into the lives of these elusive, misunderstood, and very special animals.

-CJ Puotinen is author of “The Encyclopedia of Natural Pet Care” (Keats/McGraw-Hill) and “Natural Remedies for Dogs and Cats” (Gramercy/Random House).

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