Have you noticed your once-athletic dog can no longer catch a tossed ball, or your senior pauses at a flight of stairs before descending?  It could be his vision is cloudy due to cataracts that have formed in one or both eyes.
Cataracts are opacities that develop in the clear lens of the eyes which is responsible for focusing.  They block the light and keep it from being focused onto the membrane at the back of the eye, or the retina, whose cells are responsible for generating images.  Dogs in the later stages of the condition develop a haziness or cloudiness of the lens which may be evident.  If cataracts are left untreated, it could cause blindness.  In time, cataracts can lead to uveitis which is inflammation inside the eye, and high pressure inside the eye which is a painful disease known as glaucoma.  Cataracts can come on very quickly or progress slowly in any dog at any age and may grow inside one or both lenses.
Although age can be a contributing factor in the development of cataracts in senior or geriatric dogs, hereditary predisposition and diabetes are the leading causes of cataracts in dogs.  Within one year of diagnosis, 75% of diabetic dogs will develop cataracts caused by an enzyme called aldose reductase inhibitor.  Diabetes causes high sugar levels in the blood and excessive sugar in the dog’s lens cannot be metabolized efficiently.  The enzyme traps the sugar, causing fluid buildup and protein changes that eventually lead to cataracts in dogs.  It is interesting to note that adult cats rarely develop diabetes-induced cataracts.  There are other causes of cataracts such as inflammatory diseases of the eye like uveitis, trauma to the eye, exposure to toxic substances, radiation or electric shock, while sometimes the cause is unknown.
Dog owners should be alert for subtle changes in their dog’s behavior such as bumping into furniture that has not been recently moved, hesitation when descending stairs, or seems to suddenly forget the location of his food and water bowls.  Vision impairment may not be obvious until it is advanced, therefore, it is highly recommended that your dog’s yearly exam include assessing the health condition of the eyes.  In cases where cataracts are present, a procedure call phacoemulsification is the most effective treatment which generally takes between 45 minutes to one hour per eye under general anesthesia.
If your dog is not a good candidate for surgery then regular long-term monitoring is the plan.  Examinations and assessments should be done once or twice a year by a veterinary ophthalmologist to monitor progress and to check for other ocular conditions that may be present.  There is no medication available for dogs to prevent or treat cataracts and over-the-counter oral nutritional supplements and topical drops are not effective.
*FYI:  If your senior or geriatric dog has cloudy eyes, it may not be cataracts but the more prevalent condition called nuclear sclerosis which causes lens fibers to condense and harden, giving the eyes a dull gray or bluish hue.  This condition requires no treatment and usually does not impair vision.
When all is said and done, the pivotal role in the short and long-term health of your dog’s eyes is yours.  You should examine his eyes monthly and report changes in them or in his behavior to his veterinarian and include an annual or semi-annual ocular exam.