How Much Do You Know About Eye Diseases in Dogs and Cats? Veterinarians Share the Ways to Protect the Windows of Your Fur Baby's Soul

Coming home to the innocent, watery eyes of your fur baby always takes away all your tiredness. But do you know dogs and cats like humans also need eye care? Cataracts, glaucoma, retinal degeneration, and other problems will also appear as pets grow older, but the initial symptoms can be easily ignored, and often cause irreversible damage to the eyes of fur babies.  Follow the vet’s guidelines to learn how to protect your fur babies’ eyes.

The world through the eyes of fur babies

Are you curious about the world through the eyes of fur babies? Dogs have a visual field of 240 degrees, see as far as 6 meters clearly, and can only distinguish different shades of blue, yellow, and gray.  Dogs have superior night vision and better motion visibility than humans. Cats have a visual field of 200 degrees, see objects at distances of up to 6 meters, and can distinguish blue and yellow colors. Cats’ night vision is 6-8 times better than humans, and their motion visibility is also very good.

Fur babies’ eye color

Dogs and cats under the age of one month have a grayish-blue color because the iris pigmentation is not yet fully developed. When your pet reaches three to eight weeks of age, the amount of melanin in the iris determines the color and shade of its eyes (see Figure 1). Some fur babies have different-colored eyes, known as heterochromia. This condition is common in huskies and white cats.  Heterochromia doesn’t have any impact on cats’ vision, but about 60-80% of white-coated blue-eyed cats carry the gene responsible for lacking melanocytes and inherent deafness.

Ocular structure and common eye diseases in pets

The outer layer of the dog's and cat's eye is the clear, transparent cornea; in the center is the pupil, through which light enters the lens and is imaged on the retina.  The color of the eye is determined by melanin production in the iris (see Figure 2).

• The cornea is the transparent front part of the eye.

Corneal ulcer: It is a common eye problem in fur babies. The symptoms include excessive ocular discharge and corneal edema resulting in pain and foreign body sensation in the eye. The normally clear cornea becomes cloudy, water-logged, and swollen.

• The conjunctiva rich in blood vessels and nerves is a transparent mucous membrane that lines both the inner surface of the eyelids and the anterior surface of the eyeball.

Conjunctivitis: It causes redness and swelling of the conjunctiva and sclera, excessive ocular discharge, and in severe cases, third eyelid gland prolapse. Most conjunctivitis in dogs is caused by non-infectious problems such as trauma, allergies, irritation from detergents or foreign substances, inverted eyelashes, or dry eyes. Conjunctivitis in cats on the other hand is mostly caused by infections such as feline herpesvirus and calicivirus.

• The uvea, an area rich in blood vessels and pigments, is composed of the iris, ciliary body, and choroid and is an important blood-aqueous barrier for the eye.

Uveitis: It is inflammation of the uvea that causes pain, photophobia, excessive eye discharge, clouding of the anterior chamber, and vascular congestion at the junction of the cornea and the sclera (ciliary congestion). In severe cases, inflammatory cells or pigments will be deposited in the corneal endothelium to form a grayish-white patchy pattern, and if there is an intraocular abscess or blood accumulation, it will appear dark yellow or dark red.

• The lens is a curved structure in the eye that bends light and focuses it for the retina to help you see images clearly.

Nuclear sclerosis: The eyes look foggy and white. As your pet grows older, the lens fibers continue to produce and accumulate, causing the center of the lens to be denser and cloudier.  This is considered a normal change in the lens associated with aging and vision does not appear to be significantly affected.
Cataract: The lens appears cloudy and opaque. The common causes of cataracts are inherited disease, chronic diseases such as diabetes, and aging.  Cataracts will result in decreased vision or even blindness in pets.

• The third eyelid is a glandular structure lying between the cornea and the lower eyelid that protects the eyeball and contains glands that produce the normal tear film to keep the eyes moist.

Third Eyelid Gland Prolapse: Commonly known as "cherry eye," is mostly due to congenital underdevelopment of the connective tissue at the base of the gland, and to a lesser extent due to inflammation of the gland. The incidence is much higher in dogs than in cats.

Vision check for fur babies

On a clinical basis, different tests can be used to get a closer look at your dog’s or cat's vision. For example, put fur babies in an unfamiliar environment to observe whether they can avoid obstacles. You can also use cotton balls to test their vision by putting them down above the eyes and observing whether they are aware of the falling cotton balls. The optic nerve can also be examined using the menace reaction, dazzle reflex, and papillary light reflex. In addition, the retinal function can also be evaluated by electroretinography.

Daily care for blind fur babies

For fur babies who have lost their eyesight, they need to be taken care of on a daily basis.

• Avoid changing the placement of furniture, water basins, food bowls, and potties to keep a familiar environment for your pet.
• Keep stairs off limits and reduce different floor levels in the house
• Use a leash or a pet cart when going outside and avoid excessively noisy environments

Daily care and dietary supplements

These diseases can cause severe or even irreversible damage to your fur babies’ eyesight. It is recommended to consult your veterinarian immediately when eye problems are detected and to give the best treatment plan.
Daily care:

• Avoid excessive direct sunlight on the eyes
• Wear goggles for fur babies to reduce UV damage to the eyes
• Provide suitable eye care supplements

Eye care supplements:

• Lutein: Reduce free radical damage to the eyes. Since dogs and cats cannot produce it on their own, it must be ingested from their diets such as goji berries, marigold extract, dark green vegetables, yellow vegetables, etc.
• Zeaxanthin: An important source of nutrition for the eyes, often supplemented with lutein.
• Anthocyanins and Astaxanthin: possess the powerful antioxidant capacity to reduce free radical damage to eyes. Anthocyanins and astaxanthin can be extracted from black beans, bilberry, and red algae.
• Fish oil: DHA is a nutritional source for the retina and helps in tear secretion to moisturize the eyes.

Prevention is better than cure. Daily health care and regular medical checkups are the most important principles in taking care of your fur baby's health!