For many dog owners, thunderstorms are a source of angst, a walk to the dog park can be a fraught experience, and New Year’s celebrations are particularly stressful. According to a new study of thousands of pet dogs, anxiety and fear-related behavior problems are widespread. Certain breeds are particularly sensitive to loud noises or being left alone. Other breeds may engage in compulsive behaviors such as biting themselves or urinating, suggesting a genetic component to the activity.

James Serpell, an ethologist at the University of Pennsylvania, who was not involved in the study, says that the problem stems from owners failing to properly socialize their dogs. Many canines rescued from shelters may have been inadequately trained when they were young, and the problem is compounded when new owners are overly cautious with them. “It’s a sort of helicopter-parenting concept applied to dogs,” he says. “Animals are not getting enough exposure to normal social interactions, play behavior and roughhousing with other dogs. That’s asking for trouble.”

In the study, Hannes Lohi, a geneticist at the University of Helsinki, and his colleagues surveyed Finnish owners of 13,715 pet dogs—or nearly 2 percent of the total population of the animals in Finland. The dog owners responded to questions about the dogs’ age, socialization, and behavior around humans and unfamiliar dogs and in new environments. The researchers published their results on Thursday in Scientific Reports. About 72 percent of the dogs exhibited problematic behaviors such as aggression or fearfulness. Meanwhile 32 percent of them were afraid of noises, which was the most common form of anxiety, and about one quarter were fearful of fireworks in particular. Sensitivity to loud noises increased with age. Younger dogs tended to damage property or urinate when left alone more often than older animals did. And male dogs were more hyperactive and aggressive than female ones.

Lohi also found that dog breeds had very different behavioral profiles. Romagnolos were most likely to be afraid of thunder, and Labrador retrievers were least likely to be. More miniature schnauzers, and fewer Labradors, were aggressive toward strangers than other dogs. Mixed breeds had the highest levels of inattentiveness, a trait shown in dogs considered hard to train. The breed specificity of these traits suggests that genetics plays a role in their development, Lohi says.

In a study he co-authored in January 2019 in Translational Psychiatry, Lohi and his colleagues found a gene in German shepherds linked to age-dependent hearing defects and anxiety. “But it is not really known whether this is a [physical] or psychiatric issue,” he says.

The new study also examined comorbidities, or different conditions present in the same animal. Fear and noise sensitivity were common comorbidities, although this may have been because the sample included so many dogs that exhibited each trait. And separation-related anxiety behavior was more common among dogs that were sensitive to noise. Serpell is skeptical about calling these observations comorbidities, however. The term tends to imply that a pathology is involved, but these are normal dog behaviors, he explains. Instead, Serpell says, “I would expect there to be an association between fear and aggression. A lot of aggression in dogs is triggered by fear.”

Nicholas Dodman, a veterinary behaviorist at Tufts University and chief scientist at the Center for Canine Behavior Studies, who was not involved in Lohi’s analysis, published a similar paper on behavioral problems in the July-August 2019 issue of the Journal of Veterinary Behavior. “There are some inherent pitfalls” to the questionnaire-based approach, “which apply to our study as well,” Dodman says. Surveying owners about their dogs’ behavior assumes they are vigilant witnesses, he says. And seeing a certain behavior in a canine, such as the animal scratching itself, does not explain why it exhibits that behavior. The observation does not allow an inference to be made, for instance, that the dog has developed a compulsive disorder.

Human selection for traits such as herding or guarding may have predisposed some breeds to engage in compulsive behaviors, Lohi says. In the new study, border collies, which were bred to herd livestock, were more prone to chasing lights and shadows, whereas Staffordshire bull terriers were the most likely to chase their own tails, an impulsive behavior that suggests “a genetic defect has been enriched in that breed,” he adds.

Breeding programs can gradually eliminate such traits by avoiding dogs with behavioral problems that have a genetic component, Lohi says. But selective breeding for any trait has risks, says Anindita Bhadra, a behavioral biologist at the Indian Institute of Science Education and Research, who also was not part of the new study. Attempting to breed anxiety-free dogs could bring about other problems, she says. “We know that most complex traits are multigenic, and artificial selection often leads to inadvertent changes while selecting for a set of traits,” Bhadra adds.

Lohi says the next step in understanding these behavioral issues is to tease apart what environmental, lifestyle and genetic risk factors predispose dogs to them. The overarching goal of the research is ultimately to understand how useful dogs can be to “model human anxiety and how much they share similar risk or protective factors,” he says. “Eventually, this could help to advance the health and welfare across species.”