A recent study may shed some light on why you have a barking dog!

Australian animal welfare researchers have uncovered why city-living domestic dogs may be prone to nuisance barking. In the Australian Veterinary Journal, a team from the University of Queensland's Centre for Animal Welfare and Ethics report a case-control survey of 150 dog owners, including 72 dogs whose owners had sought treatment for nuisance barking. Barking can be classified as being a nuisance when it causes distress or interruption to the life of the dogs' owners or neighbours.

The results suggest dogs most likely to become nuisance barkers are young dogs from herding breeds such as collies and kelpies, those bred in a home environment, and those that have access to the indoors or live with other dogs. The co-author of the report, Professor Clive Phillips, says the work was prompted by the high number of public complaints and inquiries about nuisance barking, with studies suggesting approximately a third of dog owners possess at least one nuisance barker.

Professor Phillips says barking may be caused by separation anxiety, perceived threats in the environment and can sometimes be simple social interaction, canine-style. But human actions and responses also play a role. In sub-tropical Brisbane, "more people may be outside and so it may be that they are more likely to notice dogs barking," Professor Phillips said.

The survey showed the greatest risk factor was the age of the dog. More than a quarter of those dogs classified as nuisance barkers were less than a year old. Professor Phillips says this is not surprising as at that age many dogs use barking as part of the learning process. The preponderance of young barkers may also occur because those dogs who are nuisance barkers at a young age do not remain in the home into old age.

The fact that herding dogs were more likely to bark also fits with the character of those breeds. Cattle dogs, German shepherds, border collies and other 'herding' dogs generally require more stimulation than other breeds.

In many cases dogs are very loyal to their owners, increasing the likelihood of separation anxiety, the study's authors write. The researchers were surprised to find that dogs bred at home were more prone to be nuisance barkers. "We had thought that dogs from shelters would be more likely to be nuisance barkers because they often arrive in shelters because of behavioural problems," Professor Phillips says. "It may be that homebred dogs are greater barkers because of greater separation anxiety."

Animal behaviour specialist and author of A Modern Dog's Life, Dr Paul McGreevy of the University of Sydney, has studied canine separation anxiety and says barking is the most common way dogs have of coping when owners leave the house.

"People worry and recognise them as problematic if the neighbours are complaining. That's the key step," he said.

"A dog that's quietly melting in distress in the backyard, or in the home, is rarely identified as a dog suffering separation anxiety."  Dr McGreevy says while the sample size of the study affects the wider relevance of the results, it is a much-needed addition to research on the topic, which is responsible for the most dog-related complaints to local councils.

By Annabel McGilvray for ABC Science Online