Cataracts are a prevalent eye issue in dogs, affecting various breeds and ages. Despite their commonality, much about canine cataracts remains a mystery. Currently, surgery is the sole treatment, with excellent outcomes when the right patient is selected. This article delves into the different types of cataracts, their onset ages, and treatment possibilities, including personal insights and scientific understanding.
What are Cataracts?
Cataract, from the Latin ‘cataractum,’ implies a breakdown in the normal structure of the lens fibers or its capsule. This disruption leads to a loss of transparency and a decrease in vision. Typically, cataracts exhibit a white or ‘crushed ice’ appearance within the eye’s lens.
Nuclear Sclerosis: A Common Misdiagnosis
Owners often present older dogs at clinics with concerns about cataract development. However, in most cases, the dogs suffer from nuclear sclerosis, a more common condition in aging dogs. Unlike cataracts, nuclear sclerosis is a natural lens change, appearing as a slight graying and affecting most dogs over six years old. It does not significantly impact vision, and treatment is unnecessary.
Cataract Formation: The Science Behind
Cataracts, regardless of their type or cause, form through a similar process. The normal lens maintains a dehydrated state, consisting of 66% water and 33% protein. A complex sodium water pump system in the lens ensures this balance. When the lens’s biomechanical system is compromised, the pump system fails, allowing extra water into the lens and an increase in insoluble protein. This leads to the loss of transparency and cataract development.
Age of Onset: A Key to Classification
The age at which a dog develops cataracts is crucial for classifying the type of cataract and determining if it’s a hereditary trait in certain breeds.
- Congenital Cataracts: Present at birth, often in both eyes, and may result from infections or toxins in unborn puppies. Some breeds, like Miniature Schnauzers, have inherited congenital cataracts.
- Developmental (Early Onset) Cataracts: Develop early in life, potentially inherited or caused by external factors such as trauma, diabetes, infection, or toxicity. Breeds like Afghan Hounds and Standard Poodles are more susceptible to inherited cataracts at this age.
- Senile (Late Onset) Cataracts: Occur in dogs over six years old and are less frequent than in humans. Often confused with nuclear sclerosis, they are not considered a medical issue.
Inherited Cataracts and Breed Predispositions
Inherited cataracts in dogs may occur independently or with other eye diseases. Certain breeds are more prone to inheriting cataracts at specific ages. If a dog is diagnosed with inherited cataracts, it’s advisable not to use them for breeding to prevent perpetuating the condition. The most common metabolic disorder leading to cataracts in dogs is diabetes mellitus, where increased glucose levels in the lens lead to rapid cataract development if not regulated.
Trauma-Induced Cataracts
Physical trauma, such as from car accidents or foreign object penetration, can damage the lens and lead to cataract formation. These usually affect one eye and can be successfully treated with surgical removal.
Treatment: Surgical Removal as the Current Standard
Canine cataract treatment involves surgical removal of the lens, with no reliable non-surgical alternatives available. Advances in veterinary surgery have made this procedure more common and effective. Techniques include full lens and capsule removal, lens removal with capsule retention, phacoemulsification, and aspiration and desiccation of the lens. Successful outcomes depend on thorough patient evaluation to ensure they are suitable surgical candidates. Diabetic dogs, aggressive dogs, or those in poor health may not be ideal candidates.
Working with a Veterinary Ophthalmologist
If you suspect your dog is developing cataracts