Cataracts in dogs

Cataracts are the loss of transparency (opacification) of the crystalline lens, which can render a dog partially or totally blind.

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Cataracts are a serious eye condition that does not only occur in older dogs, despite what one might think. Puppies and young adults in apparent good health can also contract this disease that causes partial or even total vision loss. What causes cataracts? How does it manifest itself? How does it affect the daily life and behavior of the dog? Are there any treatments? This is what we will see together.

What is a cataract?
A cataract is the clouding of the lens. This structure is one of the main components of the eye, whose role is to conduct light rays to the retina. In case of cataract, the lens loses its transparency. To be more precise, it is the outer capsule and the inner matrix of the lens that become opaque. As a result, light can no longer reach the retina, which leads to reduced vision. In some cases, this can lead to a total loss of vision.

Dogs affected by this condition can become completely disoriented, especially if it occurs suddenly and develops rapidly. The causes of the disease are diverse, and may be related to the dog’s advanced age or to another pathology.

A study conducted at the Toulouse Veterinary School has shown that certain breeds are predisposed to cataracts: Poodle and Cocker Spaniel, but also Yorkshire, Bichon or Labrit (Pyrenean Shepherd).

Age-related cataracts
When this disease is associated with the advanced age of the dog, it is called senile cataract. Due to aging, the lens becomes progressively opaque, just like in humans.

This problem appears around the age of 8/10 years, at which time the dog is considered senior.

As a rule, senile cataracts affect both eyes.

Cataracts caused by disease
Among the diseases that can lead to cataracts, diabetes is a common one. In the diabetic dog, disorders of carbohydrate metabolism affect the dog’s eye ability. Like age-related cataracts, diabetes-related cataracts usually affect both eyes.

Other ocular pathologies can also favor the appearance of cataracts, notably uveitis (inflammation of the uvea) and glaucoma, which corresponds to the elevation of the pressure inside the eye).

Congenital and hereditary cataracts
The puppy can be born with a predisposition to cataracts. However, it is very difficult to diagnose it before the age of 2 months. When it is congenital, cataracts can be a precursor to other eye diseases due to malformations.

Other forms of cataracts may appear later, around the age of two. Both eyes can be affected, but not always at the same time or at the same rate.

Thus, cataracts can occur in a variety of forms. Any cataract that occurs in a relatively young dog, of undetermined origin, should be considered as possibly hereditary. Thus, in the absence of a diagnosis, the appearance of such a cataract should lead to the exclusion of the animal from reproduction.

Cataracts due to trauma or intoxication
Blows, shocks and other traumas are likely to cause an opacification of the lens in the dog.

The same is true for toxic substances such as naphthalene (commonly used in the fight against moths), as well as molecules such as chlorpromazine, which are used in certain medications.

What are the symptoms of cataracts?
In cases of advanced cataracts, it is quite simple to notice that the dog’s pupil has become partially or totally white. This is the most tangible sign of the opacification of the lens, along with the bluish reflection in the eye.

Before that, it is the observation of the dog’s attitude that makes it possible to realize it. The animal having lost its vision can start to hit all sorts of obstacles: objects, furniture, other individuals, etc.

Some dogs become nervous, even aggressive, because they are surprised by other animals or humans who are near them without them having the opportunity to see them approach.

Can cataracts be treated?
The opacification of the crystalline lens is, most often, an irreversible phenomenon. Treatments today consist in slowing down this loss of transparency of the lens.

In older dogs, medications are administered to delay the progressive loss of vision.

Cataracts can be corrected surgically: the damaged lens is removed and usually replaced by an implant. This operation is particularly indicated for young animals, for example with a cataract caused by diabetes or a congenital disorder. In other cases, the owner and the veterinarian should consult each other to evaluate the benefit/risk ratio of such an operation. The operation is quite expensive (1200 euros on average) and is accompanied by restrictive care, including regular application of eye drops in the eyes for several weeks. However, the success rate has increased significantly in recent years following the adoption of new techniques, now reaching 90 to 95%.

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