Diagnosis and Treatment of Cataracts in Dogs
Inside the eye is a lens that focuses light on the back of the eye or the retina. Vision occurs at the retina. The structure of the eye is similar to a camera, which has a lens to focus light on the film. A cloudy or opaque lens is called a cataract.
A dog develops a cataract when the lens of the eye clouds, which is caused by changes in the water balance in the lens or changes to the proteins within the lens. When the lens becomes cloudy, light can’t reach the retina, causing blindness. A mature cataract looks like a white disk behind your dog’s iris. The part of the eye that usually looks black will now look white.
Cataracts shouldn’t be confused with nuclear sclerosis, which is haziness caused by hardening of the lens as a dog gets older. All animals experience this change with age. The good news is that light is still able to pass through and contact the retina, so your dog can still see if she has nuclear sclerosis. (She may not be able to read the newspaper anymore, but she won’t be bumping into things.) Often, people think their pets have cataracts when they really have nuclear sclerosis.
The result of cataracts is that light is unable to reach the retina. That doesn’t mean your dog is unable to see at all, just that their vision becomes very blurry.
Dog Eye Anatomy
Though the eyes of your dog are very similar to your own eyes … there are some differences.
- Dogs and other animals have three eyelids, compared to our two. In addition to the upper and lower eyelid, they also have a third, usually invisible eyelid.
- The cornea is the part of the eye you see, and where ulcers can happen. Light reflects off the back of the eyelid through the clear part of the eye. That’s the cornea.
- The iris is the colored part of the eye.
- The pupil, the black center of the eye, controls how much light gets in. In bright light, the pupil is smaller. In low light, the pupil gets bigger.
- Behind the iris is the lens, which focuses light back to the retina.
- The thin membrane that protects the sclera (see below) is the conjunctiva.
- The glands provide an oily fluid that lubricates the lids so they don’t stick when blinking.
- The sclera, or the white of the eye, is relatively tough. If your dog’s eyes are bothering her, they’ll change color. They may look reddish or pink, meaning they’re irritated or sore.
What causes cataracts?
The most common cause of cataracts in the dog is inherited disease. Other causes include injuries to the eye or diseases such as diabetes mellitus (“sugar diabetes”). Some cataracts appear to occur spontaneously and are age related.
Hereditary cataracts can affect many breeds of dogs. Breeds that are considered to be more susceptible to cataracts include the American Cocker Spaniel, Labrador Retriever, French Poodle, Boston Terrier and the Welsh Springer Spaniel to name a few.
What dog breeds are prone to cataracts?
Certain breeds of dogs are more likely to develop cataracts
- Afghan Hound
- Bernese Mountain Dog
- Boston Terrier
- Chesapeake Bay Retriever
- Cocker Spaniel
- German Shepherd
- Golden Retriever
- Havanese
- Labrador Retriever
- Maltese
- Old English Sheepdog
- Pekingese
- Samoyed
- Schnauzer
- Siberian Husky
- Staffordshire Bull Terrier
- Standard Poodle
- Welsh Springer Spaniel
- West Highland Terrier
- Yorkshire Terrier
However, it’s possible for any breed of dog to develop cataracts.
Signs & symptoms of cataracts in dogs
Cataracts in their early stages have few symptoms. One of the more common signs is a change in the appearance of the eye.
A healthy eye has a clear pupil, while an eye with cataracts will have a film over the pupil, giving it a cloudy, grayish blue texture. In some cases, the surface of the pupil will appear to have a crackled, uneven look. As dogs age, their eyes may exhibit similar changes that could also be a result of nuclear sclerosis (a harmless haziness of the pupil associated with aging) or glaucoma. While these conditions are similar in appearance, a veterinary ophthalmologist will be able to make a definitive diagnosis and provide advice on the best course of action.
Dogs with cataracts often show signs of sight loss. Some of these include:
- Clumsiness
- Bumping into furniture, door frames, walls
- Trouble finding the location of food or water bowls
- Difficulty finding toys or treats tossed to them
- Hesitant to walk down stairs
- Walking with nose to the ground
- Barking at inanimate objects
- A weeping eye or a change in blinking pattern
- Flinches when you pet near the eye
- Anxiety, especially at night or in dim lighting
Some dogs may experience dizziness, which can result in vomiting or whining. If diabetes is the underlying cause of cataracts, a dog’s water intake, along with frequent urination, may occur. Some dogs may appear restless, while others slow down and move around a lot less than usual.
While these signs can be indicators of cataracts, they can also be a result of other issues.
Since there are few symptoms in the early stages of cataracts, it can be easy to miss the signs. Be on the lookout for behavioral changes that may indicate vision problems, and pay attention to any changes in the appearance of your dog’s eye, especially as they age.
What causes cataracts in dogs?
Different factors can contribute to the development of cataracts in dogs. Some of the most common causes are:
Diabetes: Diabetic cataracts, possibly due to blood sugar abnormalities, is the leading cause of blindness in both humans and dogs. Diabetic dogs have a 75% chance of developing cataracts, and 75% of those that do will lose their vision within 6–12 months if left untreated. In terms of timing, the majority of dogs with diabetes develop cataracts within six months of diagnosis, and 80% do so within 16 months. Because cataracts in diabetic dogs can progress rather quickly, seeing a veterinarian as soon as possible is essential to avoid eye damage and loss of sight.
Aging: As dogs get older, vision-related problems, such as cataracts, can naturally develop. Certain age-related illnesses may also put a dog at higher risk.
Nutritional Imbalance: Cataracts from nutrient imbalances usually show up within the first few weeks of a puppy’s life, and result in the loss of clear transparency in the lenses. Nutritional cataracts have a good chance of improving with age, and they will usually not interfere with vision.
Trauma: For active pups that love to run and play, especially outdoors, there is the risk of potential eye trauma. The lens of the eye can rupture, which can lead to inflammation and leakage from the lens into the surrounding areas. If you suspect your dog has had trauma to the eye, see your veterinarian immediately.
Diagnosing cataracts in dogs
Cataracts can be detected just by looking into a dog’s eyes, but a veterinary ophthalmologist can make an accurate diagnosis. This may involve a physical examination to determine walking capabilities, the ability to focus on objects, and external changes in the eye, including foreign particles that could cause damage.
Other tests can include:
- Eye pressure test
- Internal examination of the eye lens
- Complete blood count test
- Electroretinography
- Ophthalmic ultrasounds
The four stages of cataracts in dogs
Each cataract is unique. Some cataracts progress at a slower pace than others, and not all follow the four stages.
Incipient: Also known as an immature cataract, an incipient cataract is a tiny cloud or opaque pocket in a dog’s eye that doesn’t require surgery. Because it’s small, an incipient cataract has minimal impact on vision and can be managed with routine care and follow-up visits with a veterinary ophthalmologist.
Immature: At this stage, a dog may need surgery due to some clouding of the lens. This condition affects 15% to 99% of lens coverage. Depending on the severity, visual impact may range from minimal to near-blindness.
Mature: This advanced stage of cataracts affects the entire lens with complete or nearly complete clouding. The eye is considerably damaged, and surgery is not always an option. Surgery is determined on a case-by-case basis because of the possible complications that can arise post-surgery.
Hypermature: The eye is in the most advanced and final stage of degeneration, and surgery might not be an option. As the cataract worsens from mature to hypermature (which can take months or even years), it causes a wrinkling of the lens, and the contents become solidified and shrunken. Vision loss is common in this final stage. Although the affected eye can become completely cloudy, there may also be clear spots, which will allow for some level of vision.
Immature, mature, and hypermature cataracts can be removed only by surgery (if your dog is a candidate); however, not all dogs with cataracts will need to go the surgical route. Some dogs may develop a cataract in only one eye, and these dogs can often avoid surgery altogether. Other dogs with cataracts can get around fine until the cataracts fully obstruct vision.
But here are some things to consider if your pup has cataracts:
Watch for injuries: Be on the lookout for changes that appear out of the ordinary. No matter how minor the injury may be, consult your veterinarian before it leads to a full-blown emergency.
Routine care: Just like humans who visit their primary doctor for regular check-ups, it’s important for pets to follow the same regimen. When it comes to cataracts, reversing them in an advanced stage is not only difficult, it can also be painful and expensive.
Home care: A nutritionally balanced diet can help keep your pet healthy in general—and that includes his eyes.
Surgery: Surgery is one of the most common treatments for cataracts. The first two weeks after surgery are the most critical time for healing; dogs need to wear a cone collar to prevent scratching and irritating the eye. Drops may also be required to prevent infection.
Corrective surgery is typically a very successful way to remove cataracts and restore vision.
What happens when cataracts in dogs go untreated?
When a cataract is left untreated in a dog, it’s possible they will go blind as the cataract completely blocks light from entering the eye. A cataract may still be treatable with surgery in the early stages after a dog loses their sight. If the cataract remains untreated after the dog becomes blind, it can eventually develop into glaucoma.
Glaucoma is a condition where the eye receives too much pressure, which leads to damage to the optic nerve. At this point, your dog will become permanently blind in that eye.
Other conditions that can be caused by leaving cataracts untreated are lens luxation and cataract dissolution. Lens luxation is a condition where your dog’s lens can float out of place. Cataract dissolution is a condition where your dog’s cataracts dissolve on their own but cause deep inflammation inside the eye, which can then result in uveitis (painful inflammation of the part of the eye known as the uvea) or glaucoma.
Luckily, not all cases of cataracts lead to blindness, glaucoma, or other medical conditions. However, in all cases it’s important to see your veterinarian for a full assessment of your dog’s condition and prognosis.
How to prevent cataracts in dogs?
Cataracts can be managed but not completely prevented. However, some basic precautions will help keep your dog healthy:
- Maintain a healthy lifestyle and body weight in accordance with your dog’s breed and age.
- Incorporate supplements with antioxidants that support healthy eye function.
- Keep your dog active with daily exercise, which helps prevent eye diseases.
- Schedule yearly eye exams, especially as your dog ages.
- If your dog suffers any trauma to the eye area, have it checked out immediately.
It’s important to stay alert to potential injuries and illnesses that can affect the eye and to feed your dog a healthy, well-balanced diet rich in vitamins and nutrients that promote healthy vision. If you own a breed that’s prone to developing cataracts, be sure to have their eyes checked regularly by your veterinarian.
DR UDAY KUMAR, CANINE SPECIALIST, HAZIPUR
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