Canine Health Menu

Cataracts

Issue Description
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light. Cataracts typically progress slowly to cause vision loss and are potentially blinding if untreated.


Causes
Cataracts can be hereditary or due to old age. Inherited conditions are the most common cause of cataracts and may be present at birth or develop when the animal is very young. They can also be caused by injury, or illness such as diabetes. If your pet's cataracts are due to an underlying condition, such as diabetes, treating the condition may diminish the cataracts.

Symptoms
Age of Onset
The age at which a dog develops cataracts is very important in classifying the type of cataract. The age of onset is particularly important for determining if the cataracts are the result of a hereditary trait in certain breeds of dogs.

Congenital Cataracts
These are cataracts that are present at birth. These cataracts usually occur in both eyes. Despite the fact that the animal is born with them, they are not necessarily inherited. Infections or toxins may cause the formation of these cataracts in unborn puppies. Primary congenital cataracts such as those found in Miniature Schnauzers are, however, inherited.

Developmental Cataracts
Developmental cataracts are those that develop early on in life. As with congenital cataracts, they may be inherited or caused by outside sources such as trauma, diabetes mellitus, infection, or toxicity. Inherited cataracts at this age are more common in several breeds including Afghan Hounds and Standard Poodles.

Senile Cataracts
The cataracts that occur in dogs over six years of age are called senile cataracts. They occur much less frequently in dogs than in humans. Nuclear sclerosis, which is not considered to be a medical problem, is often confused with cataracts at this age.

Inherited Cataracts
Inherited cataracts in the dog may occur independently or in association with other ocular disease. Some of the breeds that appear to develop inherited cataracts along with their age of onset are listed below. If a dog is diagnosed with inherited cataracts, the dog should obviously not be used for breeding because of the likelihood of perpetuating the disease in the offspring.

Trauma
Trauma from an automobile accident, or penetration of a thorn, shotgun pellet, or other object may damage the lens and a cataract may develop. These types of cataracts usually only occur in one eye and can be treated successfully with surgical removal.

Treatment
There is no effective medical treatment for cataracts. Cataracts are not painful, but when your pet has trouble navigating due to vision loss, his sight can be restored to near normal through surgery. A veterinary ophthalmologist will surgically remove the lens, replacing it with a plastic or acrylic prosthetic lens to allow for more focused vision. Cataract surgery generally has a 90-95% success rate, but it is also a very delicate procedure that requires extensive postoperative care by the pet owner.

After surgery, your pet will have to wear a protective collar (Elizabethan Collar) until his eye heals and you will need to keep him quiet and calm. Your pet will also require eye drops to be administered several times a day for a few weeks.

You and your veterinarian can decide if cataracts are affecting your pet's vision enough to warrant surgery.

Cataract surgery is a highly successful procedure, but there are risks. Chances of the pet having improved vision after surgery are high for most patients (90%-95%). But 5% to 10% of dogs will not regain good vision due to complications, and may actually be permanently blind in one or both of the operated eyes.


Scar Tissue
All dogs develop some intraocular scar tissue. Excessive scar tissue will limit vision.

Glaucoma
Glaucoma (increase in eye pressure) occurs in 30% of all dogs who have cataract surgery, usually within the first 24 hours after surgery. Most of these pressure increases are temporary and quickly resolve with treatment. Glaucoma not only can cause complete vision loss, but also may require the need for additional medications or surgery. It can be painful and cause loss of the eye if uncontrolled.

Retinal Detachment
While re-attachment is sometimes possible, the success rate is low and this complication usually results in complete vision loss.

Intraocular Infection
While it is rare, it can cause loss of the eye (i.e. surgical removal of the eye) as well as complete vision loss.

Dogs
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