Whether it is a spaniel with an insatiable love for a ball or a flat-coat that cannot be without its squeaky bear, dogs can be very keen on their toys. Now researchers say some may even show signs of addiction.

While humans can take a host of activities to excess, from work to shopping, only gambling and internet gaming disorders are officially recognised as behavioural addictions, a main feature of which is repeating acts that are initially rewarding, even though they can result in longer-term harm.

Now scientists say some dogs may have a similar relationship with their toys.

Stefanie Riemer, co-author of the study from Vetmeduni Vienna, said there were likely to be genetic and environmental factors at play.

“We think the genetic component is pretty strong,” she said, noting the team found differences in prevalence between breeds, while follow-up work suggested that owners of dogs with high levels of addictive-like behaviour did little to encourage it.

Writing in the journal Scientific Reports, Riemer and colleagues outlined how they studied 56 male and 49 female dogs, aged one to 10, some which were known to show “excessive” motivation for playing with toys.

Each owner was asked to carry out a number of tasks with their dog in a specially set-up room, often using a toy the dog had selected and sometimes with help from a researcher. These tasks included playing with the dog, the dog being left alone with the toy, throwing the toy, placing the toy in a box with a food puzzle nearby, and placing the toy on a shelf.

The researchers filmed each exercise and rated the dogs for the intensity of a variety of actions such as jumping towards the toy, barking or whining when the toy was not accessible, trying to get the toy when it was inaccessible, and not eating when food was available.

The results revealed 33 of the 105 dogs had overall scores above the median value, suggesting they were prone to such actions and hence had a high tendency for addictive-like behaviour, with the greatest proportion of such dogs being of terrier and shepherd breeds.

The team also analysed the dogs’ behaviour in terms of four of the key criteria related to behavioural addiction in humans, finding that dogs with high levels of addictive-like behaviour scored more highly for behaviours relating to craving, lack of self-control, and perceiving the toy as highly important. These dogs also tended to score higher on a scale-based questionnaire completed by owners about their dog’s addictive-like behaviour towards toys.

Riemer said the results could not conclusively prove dogs experienced behavioural addictions, while high-levels of addictive-like behaviour were likely to be less common in the general dog population.

She also emphasised that not every “ball junkie” had something akin to an addiction.

“Addiction means actually it has negative consequences for the individual,” she said. “If the dog cannot cope with the toy being unavailable, then it may be more something like addictive-like behaviour.”

Dr Serge Ahmed, an expert in addiction from the French National Centre for Scientific Research (CNRS) and the University of Bordeaux, welcomed the study but said that – as the authors have acknowledged – there was little evidence that dogs with “excessive toy motivation” experienced adverse consequences, while further work was needed to unpick how chronic the behaviour was.

“Thus, at this stage of the research, it is difficult to use this study to advise a dog owner [about]what is best for their dog.”