Dogs and cats come in all different shapes and sizes, and so do their eyes. Normal eyes have a snug fitting, black rimmed eyelid that covers up the white part (conjunctiva) of the eye. Dogs and cats also have a third eyelid that can give extra protection. It looks like a pink membrane that sits in the inside corner of the eye. The cornea is the clear and shiny, smooth surface of the eyeball. It gets all its nourishment from the tear film that constantly flows over the cornea and collects in the lower lid to drain away through the tear duct into the nose. Most of the breed related eye problems we see have to do with changes to the size of the eyes, the shape of the eyelids and the length of the nose. The most common complaints are increased tearing and corner eye stains.
Most breeds that have bigger eyes also have shorter noses. Bigger, more protruding eyes make it harder for the tears to keep the surface clean and moist. When the pet blinks, it is less effective, and the central portion of the cornea can get less tears. There is also less eyelid area to help collect the tears , and they spill over onto the fur. The end result is an overflow of tears in the corner of the eyes. Tears contain porphyrin that reacts with sunlight to form a reddish-brown stain on the fur. Dried tears can form a dark brown build up that sticks to the hair and is hard to remove. Fur around the eye can make tearing worse by touching the eye and causing irritation. Excessive tearing can build up in nasal folds causing a moist dermatitis. Other changes associated with large eyes are conjunctival pigmentation, which happens over time when the white part of the eye is exposed to air. Eyelid shape and color also have an effect on the eye. Deep, droopy lids trap more dust and irritants. Unpigmented eyelids can reflect more light and I will often see those eyes tear up more.
Any abnormalities of the eye should be checked by a veterinarian. Once a medical condition is ruled out, there are certain things you can do to manage the tearing and lessen the risk of more serious problems.
Keep the corners of your pet’s eyes clean. Wipe them daily with a soft tissue, and use a small dab of vaseline to make the tear debris easier to clean off. We have pet specific eye care wipes you can purchase at our clinic.
Trim the fur at the corner of the eyes. You can have a groomer do this if you cannot.
Warm, windy air can easily dry out a larger eye. Use protective eye gel (available at our clinic) on a daily basis, and especially before grooming appointments.
Clean nasal folds regularly. If they are deep, use a bit of vaseline to help create a moisture barrier.
If you have a dog with unpigmented eyelids, limit the time spent outside in bright sunlight, especially with the glare from snow.
Many thanks to Sue West D.V.M., Diplomate ACVO for helping me with this article.