Eyes may be the windows to the soul, but they also mirror your pooch’s health. If your buddy’s brown eyes turn blue, that should raise a red flag.

There are many reasons for eye color changes in dogs. Some are minor, like hardening of the lenses, which is a normal aging change that can cause blurred vision but isn’t painful. On the other hand, cataracts can occur at any age, and even though they’re not painful either, they can result in blindness. In some dogs, cataracts are also symptomatic of diabetes.

Glaucoma, which is caused by increased fluid inside the eye, can be very painful to your dog and can rapidly result in blindness. Anterior uveitis [you-vee-itus], or inflammation of structures inside the eye, is another painful condition.

So if you’re suddenly seeing blue when you gaze into your pooch’s eyes, consult your veterinarian as soon as possible.