Man’s best friend has long been dogged by an unflattering myth about how they are completely colour blind and can only see in black and white.

However, we might owe our canine companions an apology thanks to new research into canine colour blindness.

According to a study published in Royal Society Open Science, researchers from Italy tested the visions of 16 dogs with a specialised colour blindness test and determined that man’s best friend can perceive colour and is merely red-green colour blind (also known as Deuteranopia).

Marcello Siniscalchi and colleagues from the University of Bari Aldo Moro in Italy tested the dogs’ vision by using Ishihara’s well-known red-green colour blindness test for human, which has different-sized circles that show a written number in contrast to the background circles.

Italian scientists used a modified colour blind test to discover that dogs have trouble distinguishing between red and green. Source: University of Bari

They modified the test to show moving cat silhouettes and discovered the dogs were not able to track the movements of red cats on green backgrounds, which reinforced similar findings from other recent studies.

“If at the park you want to get your dog to catch a flying Frisbee or to bring back a ball falling on the green grass it would be better if you thought of using blue instead of red toys,” Dr Siniscalchi said.

“Overall, the direct demonstration that dogs are red-green colour blind is not only important for people directly involved in dog training but also for owners who want to improve their dog’s attentive skills during some activities such as play that is at the heart of a healthy owner-dog relationship.”

Dr Siniscalchi’s findings suggest dogs have a dichromatic colour vision – that is, they possess two types of “cone” photoreceptors, one sensitive to blue and the other sensitive to red/green.

Humans, on the other hand, possess three types of cone photoreceptors that are each receptive to blue, red AND green.

Mark Lawrie, CEO of the University of Sydney’s Veterinary Teaching Hospital, said it was a “well-conducted study” that, for the first time, adapted different techniques used in human visual assessments in dogs.

This might be a better option. Photo: Getty

“[It] confirms previous more recent studies that indicate dogs are red-green colour blind but not completely colour blind,” Dr Lawrie told The New Daily.

“Due to the conclusions from older studies, many people think that dogs only see black and white, but scientists have know for some time this is not true.”

The techniques used in the study can not only be used as a guide to develop similar colour vision tests for other animal species, but it could provide further insights into colour vision in humans.

“Dogs are an important species to do comparative studies in a number of areas that benefit humans,” Dr Lawrie said.

“There is increasing amounts research that involves analysing data from conditions in dogs that help to improve our knowledge and management of human disease.”

So, next time you take the good boy or girl to the park, you might want to consider taking a blue ball, just to make things easier for both owner and companion.