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Dog: Cataracts

General information

Other common/scientific names: cloudy lens

The lens of the eye is a focusing device. It is suspended in the eye by special fibers just inside the pupil. The pupil is the opening in the iris or colored part of the eye through which light passes. When healthy, the lens is transparent and focuses light onto the retina located in the back of the eye. The retina is the sensitive nerve tissue responsible for vision.

A cataract is defined as an opacity or cloudy change in the lens. Cataracts decrease the amount of light that reaches the retina causing impaired vision. If a cataract involves too much of the lens, the dog may be blind in that eye. Cataracts can occur in both eyes and lead to total blindness.

Abb. GGT92S1R
Abb. GGT92S1R: Schematic illustration of the eye, side view, showing the position of the lens.

Causes

The most common cause of cataracts has a hereditary basis especially in young to middle aged dogs. Breeds most commonly affected are the Cocker Spaniel, Poodle, Miniature Schnauzer, Golden and Labrador Retriever. Senile or old age cataracts are also common especially in small breed dogs. Dogs can be born with cataracts (congenital) and these may or may not be hereditary. Cataracts can also result from a systemic disease. Diabetes mellitus is the most common disease associated with cataracts. Injury to, inflammation or infection in the eye may also cause cataracts.

Cataracts can cause complications. Due to a cataract, the lens may luxate or slip from the fibers which hold it in place. A luxated lens is loose and can float in the eye causing damage. It can block drainage of ocular fluid from the eye resulting in glaucoma. Cataracts can also begin to dissolve causing severe inflammation in the eye or uveitis. This condition is painful and can also lead to glaucoma.

Cardinal symptom

Cloudy lens

Abb. GMGE26AI
Abb. GMGE26AI: Cataracts.
This is a photograph of a dog with severe cataracts in both eyes.

Symptoms

Clinical signs include a cloudy lens and reduced vision depending on the severity of the cataract. A small cataract may not restrict vision. As the cataract worsens, the pupil will dilate or widen to allow more light into the eye. With simple hereditary or age related cataracts, the eyes are not painful and the clinical signs are mild. However, if the cataract is caused by another eye disease, clinical signs will be related to the primary disease.

Diagnosis

Cataracts are diagnosed by a complete examination of the eye.

Treatment

A cataract by itself does not necessarily require treatment. If there is no associated systemic disease or other disease of the eye, it is perfectly reasonable to have a pet with reduced vision. If the choice is made not to treat for cataracts, the dog should be examined regularly by a veterinarian to detect the complications of lens luxation, glaucoma and uveitis before damage to the eye occurs.

Cataract treatment involves surgery under general anesthesia. The most common method of removing cataracts is called phacoemulsification where sound waves are used to break apart the cataract which is then removed by suction. The older method of cutting into the eye and physically removing the cataract is less commonly used. After the lens is removed, an artificial lens can be implanted to restore vision. Cataract surgery is specialized surgery which should be performed by a veterinary ophthalmologist. Dogs must be in good general health to undergo surgery and the other structures of the dog’s eye must be normal. If the dog is blind due to other eye or systemic disease, there is no point in subjecting the dog to surgery.

Prognosis

Cataract surgery with artificial lens placement is successful in 80-95% of the cases. Dogs which are not candidates for artificial lens implants will still have improved vision after cataract surgery. However, these dogs will be farsighted.

Prevention

Most cases of cataracts cannot be prevented. However, if your dog has been diagnosed with diabetes mellitus, it is important to follow treatment guidelines recommended by your veterinarian to prevent cataract formation. Contact your veterinarian immediately if you detect an abnormality with your dog’s eyes.

Tips

If your dog has reduced vision or is blind, he/she can have a good quality of life. It is important not to rearrange the furniture or leave hazardous clutter in the home. Be aware that some dogs do become more anxious or even aggressive when they lose their vision.

Dogs undergoing cataract surgery require strict aftercare and must wear a special collar (Elizabethan collar) for three weeks to prevent scratching or damage to the eye. Exercise restriction is also necessary during this time. Eye medication to reduce inflammation and recheck examinations will be needed for several months after surgery.

Abb. GMGEAQAR
Abb. GMGEAQAR: Applying eye ointment.
This is a photograph of applying eye ointment to a dog’s eye. Care should be taken not to touch the tip of the ointment tube to the eye. Place your hand on the dog’s face, under the eye to steady your hand if the dog moves and prevent touching the eye.

Abb. GMGECWYY
Abb. GMGECWYY: Applying eye drops.
This is a photograph of applying eye drops to a dog’s eye. The dog’s head should be tipped upward to allow the drops to fall into the eye. Place your hand on the dog’s face, under the eye to steady your hand if the dog moves and prevent touching the eye.

Update version: 4/24/2014, © Copyright by www.enpevet.de
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The information offered by enpevet Ltd. is intended solely for information purposes and and does under no circumstances replace a personal consultation, examination or diagnosis through a veterinarian. Thus, the information serves as an addition to the dialogue between pet owner and veterinarian, but can never replace the visit to the veterinarian. enpevet® would like to ask all users, whose animals have health concerns, to see a veterinarian as required. If you have any questions regarding the health of your animal, we recommend that you turn to your trusted veterinarian , instead of starting, changing or breaking off treatments on your own. The content of enpevet® cannot and should not be used for making your own diagnoses or for the selection and application of treatment methods.