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Cataracts and retinal diseases<br />
A Cocker’s average life expectancy is 12-14 years, but many Cockers live more than 15 (Michell,<br />
1999). There is however a risk that the final third of the dog’s life will be typified by signs of ageing,<br />
including less energetic behaviour, painful joints, dry skin and greying hairs, and nascent cataracts.<br />
Cataracts<br />
A cataract is an opacity that develops in the crystalline lens, which is located behind the iris and is<br />
normally transparent. This transparency is in part connected<br />
to the nutritive exchanges between the crystalline lens<br />
and the rest of the eye. A cataract is expressed as a greyish-blue<br />
iridisation of the eye. It can have various origins<br />
(genetic, traumatic, inflammatory, diabetic, nutritional,<br />
congenital), but it is particularly a traditional degenerative<br />
disease in dogs over ten years of age.<br />
Free radicals and cellular ageing<br />
The mechanisms of ageing are connected to the attacks<br />
on cells by highly reactive substances known as free radicals*<br />
responsible for chain oxidation reactions, which<br />
gradually destroy first the membrane then the cell<br />
nucleus. Free radicals are forming constantly in the body,<br />
but their production intensifies with age, while the body’s<br />
defence mechanisms become less and less effective. This<br />
imbalance between the action of free radicals and the<br />
body’s antioxidant protection is known as oxidative stress.<br />
13<br />
A cataract in an ageing<br />
dog is an example<br />
of the harmful effects<br />
of oxidative stress<br />
American Cocker Spaniel- © J.-M. Labat
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