Dogs that bite children have often not bitten kids before, but they tend to have underlying behavioural or medical problems, indicates research in the journal Injury Prevention.
The research team analysed the circumstances surrounding 111 cases of dog bite over a period of four years. All the 103 dogs involved had bitten children and had been referred to the same veterinary behaviour clinic.
The analysis highlighted distinctive patterns of behaviour, but not among any particular breed.
Young children were much more likely to be bitten when dogs felt their food or other resources, such as toys, were under threat. Older children bore the brunt of dogs' territorial behaviour.
Children with whom the dog was familiar were more likely to be bitten in relation to food guarding, while unfamiliar children were more likely to be bitten in relation to territory guarding.
Behavioural analysis revealed that, the guarding of resources and territory were the most common causes of aggression among the dogs.
Three quarters also exhibited anxiety, when left by their owners, or when exposed to noise, such as thunderstorms or fireworks.
Demonstrable fear may signal a tendency towards biting when faced with a perceived threat, say the authors
And young children in particular can be noisy and unpredictable in their movements, both of which could frighten an already anxious dog.
When the dogs were examined, half had medical conditions, most of which affected their bones or skin. But growths, eye problems, liver and kidney disease, hormonal problems and infections were also picked up.
The authors suggest that pain could have contributed to the dogs' behaviour. One in five dogs had never bitten anyone before, and two thirds had never bitten a child before.