Dogs guard against polar bears on Franz Josef Land archipelago. (Vladimir Melnik/National Geographic Your Shot)

Debby Ng is a journalist and visiting scholar at Colorado State University. Joel Berger is a senior scientist at the Bronx-based Wildlife Conservation Society and a professor of conservation biology at Colorado State University.

There are 700 million domesticated dogs globally. For most pet owners, these animals are companions — or “man’s best friend.” But to a penguin, a grouse or an elk, dogs can be the difference between survival and death. 

Domesticated dogs kill thousands of wild animals and livestock every month. As a result, they’ve been persecuted and poisoned from Australia to Nepal to Alaska. It’s time to rethink how we manage dog populations throughout the world and to promote policies that would humanely reduce their impact on wildlife. 

Scientists traveling to the Himalayan highlands, the Gobi Desert and far beyond to study rare animals have returned with reports of dogs chasing and killing wildlife. One dog on the loose in New Zealand killed 500 endangered kiwis in six weeks. In Australia, three dogs killed 80 penguins in one night. And in Bhutan’s premier national park, a third of the park’s young takins — an elusive and beautiful goat-antelope — were lost to dogs. 

Globally, dogs have caused about 10 extinctions and continue to threaten another 150 species. In the United States alone, some 78,000 dogs roam habitats close to urban and suburban development. From marine shores and grasslands to woodlands and coniferous forests, dogs chase and attack wild birds and deer and terrorize native predators such as gray foxes and even pumas.

Even the scent of a dog is enough to compel wildlife to flee and hide. The presence of dogs accelerates heartbeats in bighorn sheep and causes marmots to be more hesitant to reemerge from their burrows. Some animals will abandon living in an area altogether if dogs visit frequently, forcing them to give up precious opportunities to feed and travel. 

Elsewhere, dogs serve as reservoirs for a host of diseases — such as rabies, canine parvovirus and leishmaniasis (also known as black or dumdum fever). Studies from Brazil reveal that wildlife and livestock in proximity to dogs are particularly at risk of leishmaniasis, which infects roughly 1.6 million people a year. In China’s Wolong Reserve, free-roaming dogs share at least four microparasites with the reserve’s giant pandas, threatening Wolong’s precious pandas with several pathogens. 

In poor countries such as Nepal, dog populations — originally used to ward off snow leopards — have exploded. Unwanted dogs are left roaming villages, living on food scraps or hunting wildlife in forest habitats. Inevitably, conflicts mount. In the Annapurna Conservation Area, villagers routinely poison dogs with strychnine, a readily available poison that induces a long, painful death. It’s not uncommon to find dog carcasses in rivers and landfills. Sadly, when vultures and other scavengers eat the carrion, they are poisoned, too. 

But dogs are not the main problem. We are. It’s our responsibility to manage dog populations and to protect wildlife and vulnerable humans. In too many developing countries, dog management remains a reactive rather than a proactive strategy. Poisoning dogs has no lasting impact, and while culls are often touted as effective population control, they simply free up space for new dogs to claim. Many communities lack the capacity and capital to manage their dog populations. 

Managing the threat of dogs has yet to be addressed as a conservation problem for wildlife. While the impacts of habitat loss and climate change may be better appreciated, their solutions require a complex web of diverse institutions. By contrast, dog management strategies can be implemented relatively easily, at varying scales and with profound effects on biodiversity. 

Nongovernmental and nonprofit organizations working in Asia, Africa and Europe have made a tremendous impact on communities and wildlife by responsibly implementing mass neutering and vaccination programs where governments have failed to do so. Organizations such as the Global Alliance for Rabies Control and the World Health Organization advocate neutering and vaccination programs to curtail disease transmission. As a result, 15 countries and the state of Hawaii have been declared rabies-free. 

As the human population expands, these organizations require support to maintain momentum. They should also be seen as cost-saving programs in terms of health care. The cost of saving a single human life from rabies, for example, begins at $10,000, which is why rabies remains a fatal disease for people in developing countries. The annual cost of vaccinating a dog against the disease, however, is $7. 

With one dog for every 11 humans on Earth, these animals remain one of our most dominant carnivores — too often burdening a host of other species. We must work a little harder to ensure that our evolutionary bestie does not transform in our lifetime from friend to foe.

Debby Ng is a journalist and visiting scholar at Colorado State University. Joel Berger is a senior scientist at the Bronx-based Wildlife Conservation Society and a professor of conservation biology at Colorado State University.