What a cute little puppy... but few realize that in a few months they are already big beasts. And how many people know that dogs have preserved through generations many of the instincts of their ancestors, the wolves? Anyhow, children are the most exposed to dog bites, with more severe effects.

A new research made by a team led by Illana Reisner of the University of Pennsylvania has found that most dogs that bite children may not have bitten kids ever before, but their reaction has some underlying behavioral or medical causes. The researcher focused on the circumstances in which 111 cases of dog bite on children occurred, over a time period of four years. The 111 bites were inflicted by 103 dogs and had been recorded by the same veterinary behavior clinic in Philadelphia.

The investigation revealed various patterns of behavior, but the biting was not focused on any particular breed (41 breeds were involved in the investigation). Younger children (aged under 6) were much more exposed to bites when dogs perceived their food or toys were targeted, while older children were more likely to be bitten by dogs defending their territory.

Children bitten by a familiar animal were more exposed to this in connection to food defense, while unfamiliar dogs attacked kids especially because they were guarding their territory. Behavioral analysis showed that the defense of resources and territory were the main factors of aggression among the dogs.

About 75 % of the dogs displayed anxiety when abandoned by their owners or when exposed to noise, like thunderstorms or fireworks. "Demonstrable fear may signal a tendency towards biting when faced with a perceived threat," wrote the auhtors.

As smaller children can be especially noisy and unpredictable in their movements, they are more likely to induce fear into an already anxious dog. About 50 % of the dogs that had bitten children had medical conditions, especially affecting their bones or skin, but also growths, eyes, liver and kidney. Hormonal issues and infections were also among the possible causes of such reactions. "Pain could have contributed to the dogs' behavior.", wrote the authors. 20 % of the dogs had never bitten a human before, and 60 % had never bitten a child before the incident.