Now you can decipher your pet pooches true colours by the colour of his coat, for boffins have revealed that a dog's colour reflects his personality.
The latest study, recently published in the journal Applied Animal Behaviour Science, shows that golden/red English cocker spaniels exhibit the most dominant and aggressive behaviour.
Black dogs in this breed are the second most aggressive, while particolour (white with patches of colour) are more mild-mannered.
Earlier research suggests that hair colour is also linked to behaviour in labrador retrievers. For this breed, the most aggressive are the yellow ones, the next most aggressive are the black dogs and the least aggressive are the chocolate coloured ones.
The behaviour-hair colour connection is likely due to related genetic coding that takes place during the pup's earliest life stages, according to lead author Dr Joaquín Pérez-Guisado.
"Maybe the link [to coat colour] is due to the fact that the ectoderm [one of the three primary germ cell layers] is where the skin and central nervous system originate in the embryo," he was quoted by the ABC online.
Pérez-Guisado, a Spanish researcher in the Department of Medicine and Animal Surgery at the University of Cordoba, and his colleagues measured levels of dominance and aggression in 51 seven-week-old English cocker spaniel puppies that were either full siblings or half siblings.
The tests looked at how quickly a person could capture a puppy's attention, how well puppies followed the individual, how the dogs behaved while restrained, how they exerted their social dominance and what they did when they were lifted off the floor.
In many cases, the golden-coloured dogs resisted human contact and even tried to bite the tester, while the particolour pups often wagged their tails and seemed to enjoy the attention.
While genes control coat colour and appear to predispose behaviour in certain dogs, Pérez-Guisado says how dogs are raised plays the biggest role in behaviour.
He shows that environmental factors account for 80% of dominant, aggressive personalities while genes only influence 20% of dogs' demeanours."It is very important to give the dog an optimum and suitable environment in order to have a dog with a low dominance aggressive behaviour level," he says.