From obesity in cats and dogs and osteoarthritis in pigs, to cancer in whales and high blood glucose in racoons, chronic diseases are increasingly becoming a concern across the animal world, a recent study finds. Most of these ailments can be traced back to human-driven changes, the author says.
Antonia Mataragka, the study’s author from the Agricultural University of Athens, Greece, told Mongabay by email that she and her colleagues have been noticing signals “suggesting that chronic, non-communicable diseases may be emerging more frequently across very different animal populations: pets, livestock, wildlife, and even aquatic species.”
In humans, many noncommunicable chronic diseases (NCDs) are tracked through large standardized systems. But such data for domestic and wild animals tend to come from “small, isolated studies using different methods and definitions,” she added.
This prompted Mataragka to review the published scientific research to assess what’s known about chronic diseases in animals and where knowledge gaps remain.
The review found that over the past two decades, NCDs like obesity, diabetes and kidney disease appear to have increased in companion animals like dogs and cats. Meanwhile, a significant proportion of livestock, including cows and pigs, suffer from metabolic disorders, osteoarthritis and fatty liver disease.
Wildlife also show signs of chronic diseases, the review found. Researchers have documented gastrointestinal or mammary cancers among beluga whales (Delphinapterus leucas), urogenital carcinoma among California sea lions (Zalophus californianus), high blood sugar in raccoons (Procyon lotor), fibropapillomatosis, which causes tumoral growths, in green sea turtles (Chelonia mydas), and severe cardiac disease in farmed Atlantic salmon (Salmo salar).
Mataragka found that among domestic animals, lifestyle factors like diet and aging, as well as genetic factors, such as breeding for certain characteristics, increase the risk for chronic diseases.
Animal welfare conditions matter, too. For example, stress from intensive aquaculture practices has been linked to cardiac diseases in farmed Atlantic salmon.
Meanwhile, studies have linked environmental pollutants to cancers in wildlife including belugas and sea lions. Easy access to human food in urban areas is associated with high blood glucose in racoons.
Habitat fragmentation and heat stress due to climate change can also drive shifts in food and water availability, increasing the risk of metabolic and reproductive disorders in animals, the review found.
Despite the growing evidence of a problem, chronic diseases in animals, and the factors that influence them, still remain largely understudied, the review notes.
“The main implication is that chronic disease should be recognized as a potential, yet currently under-monitored, stressor for wildlife populations,” Mataragka said. “However, because the present evidence base is limited, conservation strategies must proceed cautiously and avoid overstating the role of NCDs until more robust data exist.”
Even with limited data, the review indicates that efforts like pollution control, habitat restoration and climate adaptation can support wildlife health, Mataragka added.
Banner image of a California sea lion by Rhododendrites via Wikimedia Commons (CC BY-SA 4.0)
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