‘Silent killers’ on the rise: Study links human lifestyles to chronic diseases in animals

Study warns about rising cases of chronic disease in animals. (Alexandra Bilham, Pexels)

A new study says animals around the world, from household pets to livestock and wildlife, are seeing a rise in chronic, non-communicable diseases similar to those affecting humans.

Led by Antonia Mataragka of the Agricultural University of Athens, the paper argues that conditions like obesity, diabetes and cancer are becoming more common across species.

“Many of the same factors that drive infections, like poor nutrition, distress, environmental (changes) also influence chronic diseases, like diabetes, cardiovascular diseases and cancers,” Mataragka said in an interview with CTVNews.ca.

The paper proposes a conceptual model that draws on EcoHealth and OneHealth approaches, which look at links between human, animal and environmental health.

“Non-communicable diseases (NCDs), also recognized as ‘silent killers’, develop over time due to interactions among genetic, environmental, and lifestyle factors,” the study said. “Animals suffer from many of the same NCDs as humans, highlighting that NCDs are a critical concern for veterinary and public health.”

Rising risks across species

Using existing research, the study identifies three broad drivers of chronic disease.

The first is genetics. Selective breeding in both pets and livestock has increased vulnerability to conditions such as diabetes and heart disease. Dogs and cats bred for appearance and animals bred for productivity show some of the strongest trends.

The second is environment and lifestyle, a category Mataragka says mirrors human risk factors.

“Based on the available literature, more than 50 to 60 per cent of cats and dogs are overweight, and diabetes in cats over the last 15 years has quadrupled,” she said. “Nearly 40 per cent of dairy cows suffer from metabolic diseases that lead to lower milk production.”

Veterinarians see those patterns every day.

“The impact that humans have on the lives of animals, in my field, cannot be underestimated,” said Dr. Rebecca Greenstein, medical veterinary advisor for Rover.com and chief veterinarian at Kleinberg Veterinary Hospital, in an interview with CTVNews.ca.

“When we’re seeing a rise in human conditions like obesity and diabetes, it shouldn’t surprise anyone that we would see a rise in our pets.”

The third major factor is human-driven ecosystem change. Urbanization, pollution, climate disruption and land-use change are altering how animals live and what they are exposed to.

“It all starts with climate change,” Mataragka said. “It’s increasingly influencing the rise of chronic diseases in animals by creating the environmental conditions that stress animal bodies and disrupt their normal physiology.”

She pointed to heat waves, poor air quality and contaminated water as important factors that have contributed to disorders in marine species like fish, “that are very important for our nutrition.”

Longer lives and data gaps

Some increases in chronic illness stem from longer life expectancy, a trend seen in both humans and animals, said Dr. Martin Haulena, head veterinarian at the Vancouver Aquarium.

“The animals that we have as companion animals are also living longer than they used to, he said in an interview with CTVNews.ca. ”They’re going to develop those kinds of degenerative disorders.“

That includes zoo and aquarium animals, which often outlive their wild counterparts.

“They’re going to develop cataracts, they’re going to develop joint diseases … ” he said, adding that cancer is also a possibility.

Haulena welcomed the study’s big-picture framing, but cautioned against reading the associations as proof of cause-and-effect.

“It’s more of a proposition paper, rather than a results-based paper,” he said. “You can draw a lot of associations, but you can’t draw causation or conclusions.”

The paper also identifies significant data gaps. Unlike human health, there is no global, standardized system for tracking chronic conditions in animals. Existing initiatives, such as the Global Burden of Animal Diseases programme and U.S. and EU national surveillance systems, focus mostly on infectious diseases, rather than long-term conditions.

Implications for humans

While non-communicable diseases are not infectious, the consequences ripple outward. Mataragka says metabolic and degenerative problems in livestock reduce productivity, fertility and output, adding financial pressure for farmers.

For pet owners, she says, costs are paired with emotional strain.

“There are the financial costs, but also there’s emotional stress that (they) have an animal that is suffering,” she said.

Mataragka argues that animal health often mirrors human health more directly than people realize.

“I can now say for sure that the way we live is mirrored in our pets,” she said. “When we see a pet that’s obese or is having respiratory diseases ... we must consider that an alarm for our way of living.”