Science has a name for why your dog loses its mind over a tennis ball

Doges Editorial · 2026-05-12 · 5 min read

A peer-reviewed study of 105 play-obsessed dogs found that a third showed genuine addiction-like behaviors — ignoring food, their owner, and all reason to get back to their ball. Two of them destroyed the locked box it was stored in.

Somewhere in a University of Bern laboratory, a dog is losing its mind over a ball. The ball is inside a closed container — locked, out of reach. The dog has been offered food. It has been offered its owner's full attention and an invitation to play together. The dog wants none of it. It stares at the container. It paces. It vocalizes. It tries every angle. Then it breaks the container open. Two dogs in a study published in the journal Scientific Reports — recently highlighted by pet behavior expert Steve Dale — managed exactly that. They dismantled a locked box containing their toy, illustrating, as lead researcher Alja Mazzini put it, 'how far some dogs were willing to go to access the object of their desire.'

Ball junkies: the first study to test the theory

The research, conducted by Mazzini and behavioral biologist Stefanie Riemer of the Messerli Research Institute in Vienna, is the first to formally investigate whether dogs can display addiction-like behaviors toward toys. For years, people in the training world have used the term 'ball junkie' to describe certain intensely toy-motivated dogs — the kind who will chase a tennis ball until their paws are bleeding, who pace at the sight of a leash, who seem to exist in two modes: fetching and waiting to fetch. That label implied addiction without anyone actually testing whether it applied. Mazzini and Riemer's study did.

What they measured

The study recruited 105 highly play-motivated dogs, ranging from 12 months to ten years old, representing breeds from border collies and Jack Russell terriers to Labrador retrievers and mixed breeds. Their owners had identified them as exceptionally toy-driven. Researchers set up an experimental room with four video cameras and put each dog through 14 structured tests designed to measure addiction criteria drawn from human psychology: salience, craving, loss of self-control, and the inability to regulate arousal after the stimulus was removed.

Dogs began by choosing a favorite toy from a selection — a ball, a plush, or a tug toy — or used their own if they'd brought one. Then the toy was taken away. It went on a high shelf. Into a box. Inside a sealed container while the owner actively tried to engage the dog in play or offered food. The question was simple: when the toy is gone, what does the dog choose?

One in three

For 33 of the 105 dogs — roughly one in three — the answer was always the toy, regardless of what else was available. These dogs focused on the inaccessible toy more than 50 percent of the time, even with food puzzles or their owners actively competing for their attention. They showed high arousal that did not settle even 15 minutes after all toys had been removed from the room. Some vocalized toward the shelf where the toy had been. Some paced in tight loops, returning repeatedly to the same spot.

What characterises a dog with a high tendency for addictive-like behaviour is that they seem to attribute extreme salience to their toys. They exhibit craving for them even at the expense of other rewards or interaction with their owner. Even when their toy was clearly unavailable, they still tried to access it, foregoing available food or social play.

— Stefanie Riemer, Messerli Research Institute, Vienna

The dogs who broke the box

The most striking cases were the ones who didn't just stare — they acted. Video from the study shows a Belgian Malinois systematically working at a box containing its toy, returning to it from every angle with the focused intensity of a dog who has simply decided that the container is not a permanent obstacle. The researchers say this wasn't planned; they hadn't anticipated any dog would escalate that far.

Two dogs actually managed to destroy the box containing their toy, illustrating the intensity of their motivation. It wasn't something we encouraged or expected, but it was simply a striking example of how far some dogs were willing to go to access the object of their desire.

— Alja Mazzini, University of Bern

Not broken — just very, very motivated

The researchers are careful about what they are and are not claiming. A dog who loves playing is not a dog with a problem. Toy play is entirely normal canine behavior — particularly for breeds developed for retrieving, herding, detection, or high-drive working roles, where the impulse to pursue and possess is woven into the genetics. Border collies and Belgian Malinois featured prominently among the highest scorers in the study. The paper notes: 'Playing with toys allows dogs to express instinctive predatory sequences such as chasing, catching, possessing and dissecting, considered to be intrinsically rewarding based on their species and breed histories. None of this is pathological, nor is gambling or computer gaming in people. However, such highly rewarding activities have the potential to become obsessive in humans, and the same may be true for dogs.'

The purpose of the research is not to make owners anxious about fetch. It's to give veterinarians, trainers, and behaviorists a clearer framework for something the industry has long observed but never formally defined. There is a real difference between a dog who loves playing and a dog who cannot stop — who becomes frantic at the sight of a ball, cannot settle after play ends, ignores food and signs of exhaustion alike, plays through injury. That line, the study suggests, has a biological basis worth taking seriously.

What to watch for

The warning signs Riemer and Mazzini identified are specific enough to be actionable. A dog with addiction-like toy behavior tends to focus on an inaccessible toy more than half the time even when other strong rewards are available. It shows high arousal that does not come down 15 minutes after play ends. It may vocalize toward where a toy was last seen, pace in loops, or approach the same spot repeatedly. It may ignore food — which, for most dogs, is saying something.

For concerned owners, the researchers and behavior experts suggest starting by removing the beloved toy for a month or two, then reintroducing it and observing whether the response has mellowed. More broadly, the underlying driver is often a need for more engagement — more varied terrain, more things to do with the nose and the body. Dogs who are genuinely worked during the day tend to have less tunnel vision about any single object. The walk that ends with ten minutes of ball in the backyard is probably good for both of you. The dog that lives for the ball alone — and is quietly unraveling without it — might be asking for something more.