Canine Eye Color – it’s all down to genetics!
So, what determines the color of a dog’s eyes within different breeds? The color of a dog’s eyes is controlled by his genes. In general, most dogs’ eyes are various shades of brown, regardless of the animal’s coat color. That’s because they all carry a gene which produces a brown pigment called eumelanin in the iris.
However, there are a number of different genetic factors that can cause blue, amber, or green eyes in certain breeds. One such factor is the Merle gene, and it is found on the canine chromosome 10 (CFA 10).
The Merle gene is changes coat color and eye color by creating patches with reduced eumelanin. Dogs with the Merle gene typically have irregular beige or gray patches in the base color of their fur, creating a brindled or patchy effect across the whole body. This color phenomenon is seen in many breeds, including:
Most dogs who carry the Merle gene also have blue or amber eyes. Very (like, very very) occasionally these dogs can end up with green eyes. However, for two types of dog, pale green or blue/green eyes are slightly more common. They are American Pit Bull Terriers, and Pomeranian Huskies (Pomskies).
(Incidentally, Huskies don’t have blue eyes because they carry the Merle gene, but because they carry a different gene which causes blue eyes independently of coat color.)
Night Vision and Dogs With Green Eyes!
One time when almost every dog will have green eyes is at night. Dogs’ eyes glow a ghostly green when you shine a light on them in the dark! But why do dogs’ eyes give off a green reflection?
Unlike humans, dogs and other crepuscular or nocturnal animals have a light-reflecting surface at the back of their eyes called the tapetum lucidum.
The tapetum lucidum acts just like a mirror, reflecting light from outside the eye onto the eye cells which interpret it into s.
This maximizes the use of all available light, and improves the vision of animals that are active at night or at dawn.
Some prey animals such as deer, horses, and cattle also have this visual adaptation so that they can see predators approaching under cover of darkness.
The specific eye glow color is influenced by the amount of zinc and riboflavin in the tapetum lucidum. A dog’s coat, eye color, and age can also influence the color of his eye-shine.
Older animals have denser optic lenses, which decreases the amount of light that is reflected back from the eye. My elderly German Shepherd cross’s eyes became cloudy as she aged, until her eyes barely glowed at night at all.
Do breeds with green eyes can have more health issues?
Dogs with merle genes can be prone to a few health problems, including eye problems. One eye defect that they can suffer from is colobomas.
This condition is when the part of the iris doesn’t develop fully. Colobomas can occur at birth, but it can severely affect the vision of the dog.
Dogs that have merle gens can also have the chance to develop glaucoma. Make sure to give it immediate attention since it can result in blindness.
Aside from eye problems, dogs with this gene can also suffer from hearing problems.
The gene can’t support right inner ear development, which can reduce its proper function. There I a chance that the dog can develop mild to severe deafness.