Dog bites may be more common on hot and polluted days, study suggests

Dogs may be more likely to bite people on hotter, sunnier days, and when air pollution levels are higher, new researchers suggest.

According to the study, the likelihood of dog bites occurring in these conditions increases by up to 11%.

Some research suggests humans commit more violent crimes when temperatures rise, with hotter weather and higher levels of air pollution also linked to increased aggression in humans, Rhesus monkeys, rats, and mice.

Scientists wanted to see if dog aggression against humans also followed this trend.

Writing in the Scientific Reports journal, the researchers say: “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.”

Clas Linnman and colleagues at Harvard Medical School in the US looked at data on dog bites in eight US cities — Dallas, Houston, Baltimore, Baton Rouge, Chicago, Louisville, Los Angeles, and New York City — between 2009 and 2018.

They found that dog bite incidence increased by 11% on days with higher UV levels, by 4% on days with higher temperatures, and by 3% on days with increased levels of ozone.

In contrast, dog bite incidence slightly decreased (by 1%) on days with higher levels of rainfall.

The authors reported no changes to dog bite incidence on days with higher levels of fine particulate matter (PM2.5 – an air pollutant).

However, the researchers caution that the dog bite records did not include information about other factors that can affect an individual dog’s risk of biting, such as dog breed, sex, or whether the dog had been neutered or spayed.

Additionally, there was no information about prior interactions between the dog and the bite victim, including whether the person was familiar with the dog.

According to the scientists, further research is needed to confirm and explore the relationship between aggression in dogs and higher temperatures and levels of air pollution.