Full Breed Pitbull Green Eye and One Blue Eye

Similar to humans, the presence of green eyes in the canine world is a rare but striking sight.

From Bulldogs to Beagles, almost all dog breeds sport eyes of varying shades of brown.

This is down to the Merle gene which produces eumelanin—a brown pigment—in the iris. Dogs with reduced eumelanin may develop blue, amber, or green eyes in certain breeds.

Some consider the American Pit Bull Terrier to be the only purebred with green eyes. Here, we look at other breeds known to also bear the rare genetic trait.

American pit bull terrier

The American pit bull terrier is often considered to be the only purebred dog with naturally occurring green eyes.

However, these dogs can also have blue, hazel, or brown eyes. Similarly, the color of their coats can vary across a spectrum of white, black, tan and brown shades.

Border Collie

Originally bred as herding dogs, the Border Collie is one of only a few dog breeds that have a genetic predisposition for two different colored eyes, also known as heterochromia. It is not unusual to find a dog of this breed with one blue eye, while the other may be green or brown.

Weimaraner

Weimaraners, otherwise known as "Silver Ghosts", were originally bred in Germany as a gundog to handle big game like deer and bear. Today, these family-friendly dogs are better known for their alluring green eyes, unique silver-grey coat and long velvety ears.

A six month old Weimaraner puppy guards his master during Slovakia's national canine all breeds competition in Banska, Bystrica. JOE KLAMAR/Getty

Australian shepherd

This smart, work oriented and loyal dog was originally intended to herd sheep and other animals and is still used by farmers tending to livestock.

Similar to the Border Collie, the Australian Shepherd is one of a few dog breeds that commonly has two different colored eyes. It's not uncommon to see a combination of brown, blue, hazel, amber, or green eyes in the breed.

Labrador retriever

Purebred labradors can only have brown, black or yellow eyes. However, some mixed-breed chocolate-colored labradors can be born with hazel, green or yellow-green eyes. The dogs' friendly temperament and ease of ability to train makes them one of the most popular breeds in the U.S.

Labrador green eyes — This beautiful mocha brown Labrador with lime green eyes was the first pet of former president Bill Clinton and first lady Hillary Clinton. Buddy is pictured staring out into the distance in Washington, on December 14, 1997. Getty

Dachshund

Originally bred for hunting, the Dachshund's long, lean body and snout was used to flush out badgers from underground burrows. Dachshunds can vary greatly in the color of their coats and eyes.

Great Dane

Although great Danes usually have brown eyes, some - including the harlequin great Dane—develop deep, amber-colored eyes.

Siberian husky

The Siberian husky is perhaps best known for its striking and piercing ice blue eyes. However, it is not uncommon for the breed to also sport green eyes and in some cases, even one of each. The breed, originally from Siberia (as the name suggests), can withstand cold and harsh climates with its thick coat and distinctive markings.

English springer spaniel

The English springer spaniel is a breed of gundog in the spaniel family and was originally used for flushing out and retrieving game. These enthusiastic and happy dogs usually have deep brown eyes, although some show a more amber-green hue.