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Cataracts: An Overview

Cataracts are the clouding or darkening of the lens of an eye. The lens functions as the focusing body in the eye. When malfunctions occur an increased amount of proteins accumulate in the eye and the lens becomes cloudy or opaque. Cataracts are classified a number of ways such as the age at which they appear, the cause of them, or the severity of the cataract. Classifications for the age of onset are congenital (present at birth), juvenile (present early in life), and senile (present later in life). Classifications for the severity of the cataract are incipient (one small spot), immature (covers most of the lens), mature (covers the entire lens), and hypermature (dehydration of the cataract). In cases with incipient cataracts the dog's vision is normally not hindered. With immature cataracts the dog's vision is slightly blurry. When a dog has mature cataracts vision is lost. With hypermature cataracts a mature cataract loses water and protein and basically shrivels up. This can leave clear spots in which vision may be regained but only if the rest of the eye is still functional. One may think a hypermature cataract is a good thing because the cataract is "clearing up" but in fact this process can cause more damage to the eye than a mature cataract can.

Cataracts are one of the most common eye problems in dogs today, and although they are common you should not confuse them with nuclear sclerosis. Nuclear sclerosis is a hardening of the lens which occurs normally in ageing dogs. When this happens, the eye itself becomes a blue like color, similar to the look of a cataract, but does not impede the vision of the dog. Your veterinarian will be able to tell the difference between cataracts and nuclear sclerosis. While nuclear sclerosis does not require treatment cataracts normally do.

Causes of Cataracts

The causes for cataracts vary and will determine what treatment route should be followed. Most cataracts are inherited. When this is the case cataracts will normally show up in young dogs under the age of two. Another cause of cataracts is as a side effect of another disease such as diabetes mellitus or progressive retinal atrophy. These diseases will not always cause cataracts but in many cases that is the result. Nutrition can also be a cause of cataracts. This is seen most with malnourished dogs and is one instance where the cataracts may clear up when the diet is regulated. Some cataracts will show up with no apparent cause in older dogs.

Prevention of Cataracts

Cataracts brought on by genetic causes cannot be prevented. However, cataracts caused by other diseases, such as diabetes, can be prevented by the vigilance of the owner. Be sure to watch for changes in the eye and maintaining a regular schedule of healthy pet visits to your veterinarian.

Symptoms of Cataracts

The symptoms of cataracts consist of a change in eye color, normally to a blue, gray, or white, inflammation in or around the eye, and squinting when looking at objects. An owner may also notice signs of vision loss such as reluctance to explore new places, or bumping into walls or furniture. A veterinarian can determine if the signs the dog is showing are indicative of cataracts or not.

Diagnosing Cataracts

Your veterinarian will perform a physical exam, and may refer you to a veterinary ophthalmologist. The veterinarian will look for the ability to focus on objects, walk without difficulty (running into things) and external changes. The most common test is the Schirmer Tear Test, a non-invasive test which measures the eye's ability to produce tears. Your veterinarian will also check for damage and foreign objects in the eye.

Other diagnostic tests include:

  • Eye pressure test
  • Internal examination of the eye lens
  • Complete blood count test
  • Electroretinography
  • Ophthalmic ultrasounds

Treating Cataracts

Surgery is the only proven method to remove cataracts completely. Surgery is not always needed as some cases of cataracts are small and cause no vision problems for the dog. Even though surgical treatment is not always required, all cases of cataracts should however be evaluated by a veterinarian because even mild cataracts can lead to further problems such as a lens luxation or lens induced uveitis. Both of these conditions can cause major damage and pain to the eye. In most cases they will have to be treated surgically and there is an increased risk of vision loss being permanent. If either of the conditions are likely to occur as a complication to the dog's cataracts, surgery is recommended. It is now known that the earlier cataracts are removed the greater the success rate of the surgery. In most cases surgery is very effective although there are many responsibilities owners must take on in post surgical care. This includes limiting the dog's activity, putting in eye drops multiple times a day, and taking the dog back in for follow up appointments. A veterinarian can determine if a dog is a good candidate for surgery. If you think that your dog may have cataracts or you would like more information please contact your local veterinarian.

Care for Dogs with Cataracts

It is important to remember that dogs with cataracts have trouble seeing and may possibly be blind. Dogs can do relatively well even with limited sight but there are certain things which you as an owner can do to help your dog; these include keeping the furniture in the same place and keeping floors clear. Dogs will quickly adapt to clear paths and be able to navigate familiar spaces with ease. When taking your dog to a new place, be sure to introduce them to their surroundings by leash walking them around the area. When it comes to medications follow your veterinarian's instructions to have the greatest success in the treatment of your dog's cataracts.

The AKC Canine Health Foundation and Cataracts

The AKC Canine Health Foundation has funded 11 grants totaling over $395,000 toward cataract research. The funds have gone to projects researching the causes and new treatments of cataracts. With your help we can continue to fund research which may provide better treatments for cataracts and also help prevent them in the future.

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