Cataracts in Dogs
A cataract is a cloudiness within the lens of the dog’s eye. The lens of the eye works much like the lens of a camera, helping to focus on objects so that the dog can see them clearly. When cataracts affect a big part of the lens, they cause vision loss and may lead to blindness.
Every dog experiences cataracts differently. A cataract may develop rapidly or over a period of time. There are four stages of cataracts:
- Incipient cataract is a small cataract that doesn’t interfere with vision. It typically occurs with age and often goes unnoticed. However, it can progress and become more significant.
- Immature cataract involves a larger part of the lens, which may start to affect vision.
- Mature cataract is when the dog’s entire lens is blocked by the cataract and there is no vision.
- Hypermature cataract is when the lens starts to shrivel up due to water and protein loss. In young dogs, some vision may return.
The most common cause of cataracts in dogs is genetics, and hereditary cataracts are more likely to develop in the following breeds:
- Australian shepherd
- Bichon Frise
- Cocker spaniel
- Miniature poodle
- Miniature schnauzer
- Silky terrier
The second most common cause of cataracts in dogs is diabetes mellitus. While genetic cataracts develop over a period or months or years, cataracts that are secondary to diabetes tend to progress very quickly. About 50% of diabetic dogs will develop a cataract within a year of diagnosis.
Less common causes of cataracts include inflammation and trauma.
One of the more common signs is a change in the appearance of the eye. A healthy eye has a transparent pupil, while an eye with cataracts will have a cloudy white film covering part or all of the pupil.
While cloudiness in a dog’s eye is the telltale sign of cataracts, it’s important to note that it can occur for other reasons as well. If your dog is older, the cloudiness may be due to nuclear sclerosis, which is the natural hardening of a dog’s ocular lens. Your veterinarian will likely refer you to a veterinary ophthalmologist, who specializes in eye diseases, to ensure your dog is diagnosed correctly. The following tests help confirm the diagnosis:
- Ultrasound to look for any issues in the back of the eye, such as retinal detachment
- Electroretinogram to test the function of the retina behind the cataract.
- Blood and urine tests to see if the cataract may be due to diabetes
The only treatment for a cataract is to remove it through surgery. The cataract is removed by a method called phacofragmentation, which involves splitting the cataract into smaller pieces and then removing the pieces through a very small cut in the dog’s eye. This surgery lets light reach the retina, allowing your dog to see again.
After the cataract is removed, a new lens, called an intraocular lens (IOL), is sometimes implanted to improve the dog’s vision further. If it is not possible to implant an IOL, your dog still will be able to see after surgery but will be farsighted.
If the surgery is successful and there are no issues, you will need to follow a strict routine to make sure your dog’s eyes heal properly. Your dog will need to rest for at least two weeks and wear an Elizabethan collar for three weeks so that he doesn’t scratch or irritate his eye. You will need to administer several different types of eye drops at least four times a day and give additional medications orally. Your veterinary specialist will want to see your dog several times after surgery to make sure he is healing and there are no complications.
While it is a difficult process, the success rate for surgery is high, with nine out of ten dogs having good (but not perfect) vision after recovering from surgery.
Since there is no way to prevent hereditary cataracts, it’s important to schedule regular veterinary visits so that changes in your dog’s eyes will be caught as early as possible. If your dog has diabetes, treating the underlying condition may decrease the likelihood that cataracts will develop.
AMC’s Usdan Institute for Animal Health Education event from August 2019: Alexandra van der Woerdt, DVM, Staff Doctor & Head of Ophthalmology at the Animal Medical Center offers insight into the signs, diagnosis, and treatment of cataracts in pets.