Can a Dog See Colours? ...
{Courtesy of Brianna Talbot}
For many years it has been thought that the dog could only see black and white, now as more research has been carried out on dogs and their ability to see, I thought I would shed some light on the matter and clear up the misconception that dogs cannot see colour!
The dog’s sense of vision is specialised for maximal efficiency under low light and the retina contains two primary types of light receptors: rods and cones. Rods are specialised for low-intensity light and are the predominant type of receptor found in the dog’s retina. Studies of dog and human’s vision have shown that the dog’s absolute threshold for the detection of light is threefold lower than that of humans. In English, this means dogs are three times more capable of detecting low intensities of light than us. Cones are essential for the detection of high intensity light and are responsible for the perception of colour. The dog possesses a much lower density of cones than rods in the retina and has a much lower concentration of these receptors compared to humans. Recent studies have found that under bright lights, dogs are capable of detecting some colours, specifically colours within the light spectrum of blue and yellow. They are however incapable of distinguishing between red and orange. Therefore, our little four-legged friends are capable of seeing two pure colours, blue and green, along with a combination of these two colours and they are therefore referred to as being dichromatic animals!
In addition, the dog has a special adaptation that allows them to see better in dim light. It is called a tapetum and is composed of reflective cells that are located immediately behind the retina. This functions to capture stray light beams and reflect this scattered light back onto the photoreceptive cells of the retina. By having this adaptation, it is thought that this increases the dog’s light-catching abilities by 40%! The tapetum is also responsible for ‘red eyes’ that are seen when a light is shone into a dog’s eyes.
Dog's eyes are very sensitive to moving objects and can see a hand waving up to a mile away but are not very good at seeing static (stationary) objects. Though they are nearsighted when it comes to recognising detail but are good at perceiving outlines and in 1992, it was realised that dog’s vision does not mature until it is four months old. Because of the placement of the eyes on the skull, most dogs have good lateral vision (side vision). The further to the side the eyes are, the greater the field of view. The panoramic field of view is 250-270º but binocular vision varies greatly in different breeds according to their eye set. For example, the Pekinese or Bull Terrier has binocular vision of about 85º, while Greyhounds have 75º and we have 140º. This means a dog judges distance poorly compared to humans but can detect movement over a much wider field of vision than humans.
So, if you're training at dusk or doing long distance work, think about what you are wearing so that your dog will be able to see you and it might make recalls a little easier!