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Primary Lens Luxation in Dogs

What Is Primary Lens Luxation in Dogs?

Primary lens luxation in dogs occurs when the small ligaments, known as zonules, which hold the lens in place within the eye, deteriorate. This deterioration leads to the displacement or “luxation” of the lens from its normal position.

There are two types of primary lens luxation: anterior and posterior. Anterior luxation happens when the lens falls forward, while posterior luxation occurs when it falls backward.

Anterior luxation is particularly concerning because it can obstruct the normal drainage of fluid from the eye, resulting in increased pressure known as glaucoma. Glaucoma is extremely painful for dogs and can ultimately lead to permanent blindness.

Given the severity of the consequences, primary lens luxation is considered a medical emergency in dogs. While anterior luxation can cause intense pain and potential vision loss, it is not typically a fatal condition in dogs.

Symptoms and Types

Signs of primary lens luxation in dogs encompass:

  • Excessive tearing
  • Squinting
  • Cloudiness or haziness in the eye
  • Pain
  • Reddish discoloration of the eye
  • Alteration in pupil size or shape
  • Presence of a white spot in front of the iris (the colored portion of the eye)

Causes

Primary lens luxation is triggered by a hereditary condition characterized by the weakening and deterioration of the ligaments responsible for holding the lens in position. Conversely, secondary lens luxation arises subsequent to issues within the eye, such as inflammation, glaucoma, cataracts, malignancies, or physical injury.

Typically manifesting during young adulthood, primary lens luxation commonly affects dogs aged between 3 and 8 years. This condition is particularly prevalent among breeds such as:

  • Jack Russell Terriers
  • Bull Terriers
  • Yorkshire Terriers
  • Australian Cattle Dogs
  • Border Collies
  • Chinese Crested
  • Chinese Shar-Pei
  • German Shepherds

Diagnosis

Diagnosing lens luxation entails a thorough eye examination, also known as an ophthalmic exam, conducted by your veterinarian. This examination involves the use of an ophthalmoscope to inspect the interior of your dog’s eye.

Additional diagnostic tests that may be performed at your veterinary clinic include tonometry and Schirmer’s tear testing (STT). Tonometry utilizes a device called a Tono-pen to assess your dog’s eye pressure, while Schirmer’s tear testing measures tear production using small test strips. In some cases, your veterinarian may recommend referral to a veterinary ophthalmologist for further evaluation, which might include eye ultrasound to examine internal eye structures and discuss treatment options.

It’s important to communicate with your veterinarian about any symptoms your dog may be experiencing, such as eye discharge, squinting, or changes in eye color, and when these symptoms were first noticed.

Treatment

The treatment for primary lens luxation involves surgery, typically performed by a veterinary ophthalmologist if diagnosed early. During a lensectomy, the lens is removed through a small incision in the eye. The incision is then closed with tiny absorbable sutures.

Dogs undergoing this procedure can still retain vision, although they may become farsighted without the lens. Post-surgery, there are potential complications such as inflammation, glaucoma, and retinal detachment, necessitating lifelong medication.

In cases where lensectomy isn’t feasible, the affected eye may be surgically removed, a procedure known as enucleation, which can be performed by a regular veterinarian.

While anterior lens luxation can rapidly lead to severe complications like glaucoma, pain, and blindness, posterior lens luxation is typically less severe. Management of posterior lens luxation often involves the use of topical medications to maintain pupil constriction, preventing the lens from dislocating forward.

Recovery and Management

After surgery, your dog’s recovery typically involves a strict two-week period of rest. They may need to stay at the veterinary hospital for a few days post-surgery. Once discharged, it’s crucial to limit their activity levels.

During outdoor activities, only leash-walking is recommended. Use a kennel as necessary to prevent running, jumping, or navigating stairs. Your dog should wear a recovery cone to deter pawing at the face, and administer post-operative medications as prescribed.

If maintaining restricted activity proves challenging, consult your veterinarian about the potential use of a mild sedative like trazodone to aid in managing your dog’s recovery.

Prevention

Since primary lens luxation is hereditary, prevention primarily involves refraining from breeding affected animals.

However, since most affected dogs don’t experience lens luxation until around 3 years old, and many breeding decisions are made before that age, genetic testing is available to identify if your dog carries the predominant gene linked to primary lens luxation, the ADAMST17 gene.

If one eye has been affected by primary lens luxation, it’s common for the condition to progress to the other eye. Regular comprehensive eye exams for your dog can facilitate early detection, potentially preventing rapid deterioration and vision loss in the other eye.

 
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