Why Are a Dog’s Eyes Blue?

1 Overview

Blue Eyes from Infectious Hepatitis

Canine infectious hepatitis is an acute, highly contagious septicemic disease in dogs, also called ‘blue eye disease’, spread by direct contact with a sick dog’s secretions and excretions.

Early infection looks like acute flu: fever, low spirits, poor appetite, sticky eye/nose discharge, but no cough. Then vomiting, jam-like diarrhea, bleeding spots on gums. Some dogs show a swollen belly; some show one or both eyes covered by a blue film, which turns clear after a few days.

The hepatitis virus is strong; even after recovery it can live in the kidneys for 6-9 months, during which a healthy dog contacting the recovered dog’s urine can be infected. So for your dog’s health, get the relevant vaccine yearly at a proper pet hospital.

Blue Eyes from Cataracts

As dogs age, cataracts also appear from lens degeneration or from acquired causes. The eye gets a white film with a blue glow, and the eye turns blue.

In late cataracts the dog’s vision is near zero, seriously hurting life; now many hospitals can do cataract surgery to restore sight.

Blue Eyes from Albino Genes

Fully albino dogs are rare in real life (they barely survive due to severe degeneration). In extreme albino positioning, cells in white-coated areas cannot make pigment; a Border Collie can show this on one side of the face, with a blue eye on the white side. Albinoism is a very bad sign, so such dogs are not advised for breeding.

Natural Blue Eyes

The Husky has a gene that singly controls blue eyes. A duplication of the ALX4 gene was found on dog chromosome 18, likely tied to blue eyes and key to the Husky’s blue eyes.

Blue Eyes in Puppies

A puppy that just opened its eyes a few days ago has a blue film over the eyeball, but it gradually disappears with time.

Strictly, the blue a puppy sees is not the eye’s color. A puppy is born with blue eyes because the melanin in the eye forms only weeks after birth. Before melanin exists, we see the blue from light reflecting and refracting on the iris. As the dog grows, melanin forms in the iris, and that pigment deposition finally gives the eyes their different colors.

There are many more causes of blue eyes; we listed only the most common. As long as it is not pathological blue eyes, owners need not worry too much; if blue eyes make the pet uncomfortable, see a vet soon.