6 Common Eye Problems in Dogs
Two veterinary ophthalmologists on the eye issues you should look out for.
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“Puppy dog eyes” get me every time. It’s been proven that gazing into your pet’s eyes produces oxytocin and promotes bonding. But if their eyes have been looking a little red or cloudy lately, or if you’ve noticed they’re pawing at, rubbing, or showing signs of irritation around their eyes, you might need to make an appointment with your vet.
Eye problems in dogs are no joke — dogs can suffer from a host of health conditions including glaucoma, conjunctivitis, dry eyes, cataracts and more. Some eye disorders occur more often than others (a dog’s breed usually plays a role).
“As a general practitioner, I was often presented with problems such as conjunctivitis, dry eye and corneal ulcer,” says Dr. Christine Lim, DVM, DACVO, a veterinarian in Chicago. “Now that I specialize in ophthalmology, I more often see cataracts, glaucoma and retinal disorders.”
How Dogs’ Eyes Work
To understand eye problems in dogs, it helps to know a little bit about how their eyes function. A dog’s eyes work much like a camera. Light enters through the pupil, and the iris controls the amount of light allowed in. Light then passes through the cornea and lens, which focus the light on the retina, a layer containing color-sensitive cones and motion- and light-sensitive rods, which convert light into electrical signals. The cones and rods send these signals via the optic nerve to the brain, which constructs an image from them.
Dogs have only two types of cones, compared with the three types in human eyes. As a result, dogs don’t see as many colors as do people. Dog eyes also contain structures not found in a camera, such as the gel-like vitreous humor that fills the eyeball and gives it shape. Canine eyes are different than human eyes in that they have a third eyelid called the nictitating membrane, a thin whitish-pink tissue that protects the eye. And unlike humans, dogs have a reflective lining behind the retina called the tapetum lucidum, and it’s what makes dogs’ eyes glow eerily when light hits them. It’s also what allows them to see in dimmer light.
The visual streak is a horizontal band in the retina right above the optic nerve; this area has the highest concentration of rods and cones, and vision is sharpest here. The visual streak varies greatly among breeds, and studies suggest that different breeds see the world differently. In dogs with long heads like wolves, the streak is wide, with the nerves evenly distributed. The shorter a breed’s head, the narrower (more circular) the streak tends to be. Pugs, for example, have a small spot of sharp vision — an “area centralis” — as humans do. Even within breeds, the visual streak can vary from type to type.
How Well Do Dogs See?
All of these features equip a dog to be a good hunter under various light conditions. The tapetum lucidum improves a dog’s vision in low-light, as does the high proportion of rods to cones, giving dogs better vision at night than humans. A rod-dense retina also makes dogs excellent at detecting motion and shapes. Because most dogs’ eyes angle slightly to the side, they have a wider field of view than humans. When a wide field of vision combines with a wide visual streak, as in a German Shepherd, a dog can see the whole horizon at once (instead of having to scan the eyes back and forth as humans do).
With keen senses of smell and hearing, dogs don’t need to see well up close; in fact, near vision is blurry in long-nosed dogs. (Short-nosed dogs, with their human-like area centralis, do appear to see well up close. Though the area centralis may lessen their ability as hunters, it may make them better lapdogs, more able to “read” their owners’ faces.) Overall vision is also less sharp.
6 Common Dog Eye Problems
Below are the most common eye problems in dogs. (Note: Some dog breeds are more prone to eye problems than others, and a mixed-breed with one of those types in the mix could also be affected.)
1. Conjunctivitis in Dogs
Conjunctivitis is a condition in which the lining of the eyelids and the front of the sclera (the white of the eye) become inflamed. It can be caused by infection, an object in the dog’s eye, an allergic reaction, dry eye, a scratch, or even smoke or dust, and can also be a symptom of other diseases. Treatment depends on the cause.
2. Dry Eye in Dogs
Dry Eye is when not enough tears are produced to keep the eyes properly lubricated. Dogs may inherit this condition; among the dog breeds at higher risk are the American Cocker Spaniel, English Bulldog, Pug, Lhasa Apso, Pekinese, Shih Tzu, and West Highland White Terrier. Small, flat-faced dogs sometimes have eyes that bulge so much that their eyelids cannot close, which makes the surface of the eyes to dry out.
Dry eye may also result from an immune system reaction, an injury or a drug side effect. Dryness can be a serious problem for dogs because dry eyes are easily irritated and may develop conjunctivitis or corneal ulcers. Artificial tears, good eye hygiene, anti-inflammatory drugs and/or cyclosporine ointment (Optimmune) may help. If the cause is known, the veterinarian treats that as well.
3. Corneal Ulcer In Dogs
Corneal Ulcer is a slow-healing sore on or in the dog’s cornea, accompanied by inflammation. Most ulcers are caused by injuries, and treatment often involves antibiotics. Small dog breeds with very short noses and big eyeballs are more prone to eye injuries, says Dr. Samuel J. Vainisi, DVM, ACVO of the Animal Eye Clinic in Denmark, Wisc. “Because of that, we see a lot of ulcers on the eyes of breeds such as the Boston Terrier, the Pekinese, and the Shih Tzu.”
4. Cataract In Dogs
The most common cause of blindness in dogs, cataract is a clouding of the lens that obscures the dog’s vision. Most dogs with cataracts inherited the tendency to develop them. Inherited cataracts can occur in the Afghan Hound, American Cocker Spaniel, Boston Terrier, Chesapeake Bay Retriever, German Shepherd, Golden Retriever, Labrador Retriever, Miniature Schnauzer, Norwegian Buhund, Old English Sheepdog, Schnauzer, Siberian Husky, Staffordshire Bull Terrier, Standard Poodle, Welsh Springer Spaniel, and West Highland White Terrier. Diabetes, injuries, poor diet and aging can also lead to cataracts.
Surgery is available to treat dogs with cataracts. Removing the lens allows light to again enter the eye. For best post-surgery vision, the natural lens is usually replaced by a plastic lens. “The surgery itself is not too stressful for the majority of patients,” says Dr. Lim. However, “the first few weeks postoperatively can be stressful because it is very intensive — the patient must wear an Elizabethan collar at all times, and several medications are required.”
5. Glaucoma In Dogs
Glaucoma is the elevated pressure of the fluid inside the eyeball caused by fluid draining more slowly than it is produced. Dogs with glaucoma can experience damage to the retina or optic nerve.
Most often, dogs get glaucoma because they inherited an eye structure that leads to poor drainage. Dog breeds in which primary (inherited) glaucoma occurs include the Alaskan Malamute, American Cocker Spaniel, Basset Hound, Beagle, Boston Terrier, Bouvier des Flandres, Chow Chow, Dalmatian, English Cocker Spaniel, English Springer Spaniel, Great Dane, Labrador Retriever, Norwegian Elkhound, Poodle (all sizes), Samoyed, Shar-Pei, Shih Tzu, Siberian Husky, and Welsh Springer Spaniel.
Primary glaucoma has no obvious cause, and it affects both eyes (although one eye may develop glaucoma earlier than the other). Secondary glaucoma is glaucoma that is caused by a dislocated lens, injury, tumor or other problem that decreases fluid drainage in the eye; it may affect just one eye.
Glaucoma treatments include surgery, pills, eye drops or (rarely) removal of the eyeball. “Glaucoma is still one of the more difficult things to handle,” says Dr. Vainisi. “Even though there are literally dozens of glaucoma procedures, there still is not that ideal one … even in humans.”
6. Retinal Disorders In Dogs
“Progressive retinal atrophy” (PRA) is the name for a group of retinal disorders in which rods and cones die off; there is no treatment. Dogs who get PRA do so because they’ve inherited a defective gene. Although PRA strikes more than 100 breeds of dogs, different genes are responsible. Therefore, breeds differ in the age at which the condition appears, how fast the condition progresses, and the ratio of males to females among affected dogs.
PRA appears during puppyhood in the Cardigan Welsh Corgi, Cairn Terrier, Collie, Gordon Setter, Great Dane, Irish Setter, Miniature Schnauzer and Norwegian Elkhound. In contrast, some breeds usually don’t develop PRA until adulthood. These include the American Cocker Spaniel, English Cocker Spaniel, Labrador Retriever, Lhaso Apso, Miniature Poodle, Portuguese Water Dog, Tibetan Spaniel and Tibetan Terrier. PRA occurs mostly in males in the Siberian Husky and Samoyed. Genetic tests for PRA are available for several breeds.
Other retinal problems include detachment of the retina from the back of the eye, inflammation and abnormal development. Causes include infection and injury. Some retinal disorders have no treatment, while others can be helped by surgery or treatment of the cause.
Small dogs may be more prone to retinal detachment. According to Dr. Vainisi, several small breeds of dogs, including Boston Terriers, Jack Russell Terriers and Shih Tzus, love to pick up toys and shake them hard. “Fluid goes violently back and forth in the back of the eye, and it just rips the retina right off,” he says. “One moment they’re seeing, and the next moment they can be totally blind.”
How to Treat Your Dog’s Eye Problem
The best way to protect your dog’s vision is to catch eye disorders early, when they are most easily treated. A dog with eye or vision problems may paw at or scratch their eye, squint, bump into things, become afraid of the dark, or be frightened in situations that did not frighten them before. The dog’s eye may produce discharge, be red, look cloudy or be swollen. The nictitating membrane may partially cover the eye.
If your dog seems to have an eye problem, take them to the veterinarian right away. Your vet may have the knowledge and equipment to diagnose and treat the problem immediately; if not, they may refer your dog to a veterinary ophthalmologist, a specialist in animal eyes and their disorders.
Only about 300 veterinarians in the United States have board certification from the American College of Veterinary Ophthalmologists. As a result, if your dog needs a veterinary ophthalmologist, you may need to travel to see one. Some, but not all, veterinary ophthalmologists see dogs only by referral.
The bottom line: If your dog has an eye issue, make an appointment with your vet right away. That way, your dog won’t need to suffer or develop a worse issue unnecessarily.
Cloudy eyes could be a sign of cataracts. Here’s how to spot them and help your dog see more clearly.
For starters, how to prevent it. But also, which breeds are at risk, what symptoms you should look out for, and what treatment options are out there.
Shauna S. Roberts, PhD
Shauna S. Roberts, PhD, is an award-winning science and medical writer and copyeditor who specializes in arthritis, diabetes and related subjects.