Heat, sunlight, and pollution might make some dogs bite-happy, new research out Thursday suggests. The study found that reported dog bites tend to increase on days with higher temperatures as well as days with higher UV or certain pollution levels. Though more research will be needed to confirm the findings, the authors say, other studies have found a similar link between hot weather and aggression in humans and other animals.
The research was led by scientists at Harvard Medical School. They examined publicly available dog bite data from eight U.S. cities, including Los Angeles, Houston, and New York City, from 2009 to 2018. Then they cross-referenced the data with daily weather and pollution data in those cities.
All in all, there were almost 70,000 recorded dog bites during the study period. And the team found a connection between bites and the surrounding environment. Compared to days with lower UV—or low sunlight exposure—recorded dog bites went up by 11% on higher UV days. They also went up by 4% on higher temperature days, and by 3% on days with higher levels of ozone, a common pollutant. Dog bites slightly decreased on days with more rainfall, and remained unchanged no matter the level of exposure to another type of pollution, fine particulate matter, or PM2.5.
“We conclude that dogs, or the interactions between humans and dogs, are more hostile on hot, sunny, and smoggy days, indicating that the societal burden of extreme heat and air pollution also includes the costs of animal aggression,” the authors wrote in their paper, published Thursday in Scientific Reports.
The study does have its limitations. For one, the authors lacked data on other important factors that might have influenced the risk of dog bites, such as breed, sex, whether the dog had been neutered or sprayed, or the relationship between the dog and its victim. This data also represents more severe dog bites and not the many mild injuries that go unreported. And of course, this type of research can’t prove a cause-and-effect relationship between dog bites and the environment, only establish a correlation.
That said, plenty of studies have found a link between hot weather and increased aggressive behavior in other animals, including humans. One common finding, for instance, is that violent crime tends to go up during the summer. In humans, this link is likely the result of several factors. Up until a certain point, warmer temperatures and sunshine tend to make people go outdoors more, for instance, which could then provide added opportunities for conflict. But the heat itself might make us crankier and more prone to violence. There have been fewer studies on pollution specifically, but some research has suggested a similar negative effect from higher ozone exposure.
As with other animals, it’s possible that heat and pollution can directly affect canine behavior. But these factors might also change how humans behave around dogs in ways that make biting more common. So the authors say that more research has to be done to truly validate and understand this connection.
If the link is genuine, then dog bites are poised to become another item on the long list of things that climate change will make worse—right next to worse allergies, more disease-carrying ticks, and wildfires.
Heat, sunlight, and pollution might make some dogs bite-happy, new research out Thursday suggests. The study found that reported dog bites tend to increase on days with higher temperatures as well as days with higher UV or certain pollution levels. Though more research will be needed to confirm the findings, the authors say, other studies have found a similar link between hot weather and aggression in humans and other animals.
The research was led by scientists at Harvard Medical School. They examined publicly available dog bite data from eight U.S. cities, including Los Angeles, Houston, and New York City, from 2009 to 2018. Then they cross-referenced the data with daily weather and pollution data in those cities.
All in all, there were almost 70,000 recorded dog bites during the study period. And the team found a connection between bites and the surrounding environment. Compared to days with lower UV—or low sunlight exposure—recorded dog bites went up by 11% on higher UV days. They also went up by 4% on higher temperature days, and by 3% on days with higher levels of ozone, a common pollutant. Dog bites slightly decreased on days with more rainfall, and remained unchanged no matter the level of exposure to another type of pollution, fine particulate matter, or PM2.5.
“We conclude that dogs, or the interactions between humans and dogs, are more hostile on hot, sunny, and smoggy days, indicating that the societal burden of extreme heat and air pollution also includes the costs of animal aggression,” the authors wrote in their paper, published Thursday in Scientific Reports.
The study does have its limitations. For one, the authors lacked data on other important factors that might have influenced the risk of dog bites, such as breed, sex, whether the dog had been neutered or sprayed, or the relationship between the dog and its victim. This data also represents more severe dog bites and not the many mild injuries that go unreported. And of course, this type of research can’t prove a cause-and-effect relationship between dog bites and the environment, only establish a correlation.
That said, plenty of studies have found a link between hot weather and increased aggressive behavior in other animals, including humans. One common finding, for instance, is that violent crime tends to go up during the summer. In humans, this link is likely the result of several factors. Up until a certain point, warmer temperatures and sunshine tend to make people go outdoors more, for instance, which could then provide added opportunities for conflict. But the heat itself might make us crankier and more prone to violence. There have been fewer studies on pollution specifically, but some research has suggested a similar negative effect from higher ozone exposure.
As with other animals, it’s possible that heat and pollution can directly affect canine behavior. But these factors might also change how humans behave around dogs in ways that make biting more common. So the authors say that more research has to be done to truly validate and understand this connection.
If the link is genuine, then dog bites are poised to become another item on the long list of things that climate change will make worse—right next to worse allergies, more disease-carrying ticks, and wildfires.