Pet Care Tips
The eye is a complicated structure
with many different parts that all have to work together and function
correctly for a dog to see. The part of the eye that focuses light
is called the lens. It is located in the middle of the eye within
the pupil and is surrounded by the colored tissue that forms the iris.
A healthy lens is clear, so it is invisible under normal circumstances.
A cataract is an abnormal, cloudy area
within the lens through which a dog cannot see. Cataracts can
involve just a part or the entire lens in one or both eyes.
What Causes Cataracts
Cataracts can form for a variety of
reasons. Eye injuries or inflammation play a role in some cases
and so can genetics in certain breeds including cocker spaniels, Siberian
huskies, poodles, schnauzers, bichon frises, Old English sheepdogs,
and some types of retrievers, spaniels, and terriers. Cataracts
are more common as dogs age, probably because damage caused by ultraviolet
light and other sources has a chance to accumulate.
Dogs that have diabetes mellitus almost
invariably develop cataracts, even if their disease is otherwise well
controlled with insulin. The extra sugar in the blood stream of
a diabetic dog is absorbed by the lens causing it to retain water, swell
and lose its transparency.
The Symptoms of Cataracts
Cataracts look like white or blue-grey
areas of discoloration within a dog's eye. They can come in
different shapes and sizes depending on how much of the lens is involved.
Some progress over time, while others do not change. Depending
on the underlying reason for cataract formation and possible damage
to the eye caused by the cataract, other symptoms like redness and discharge
may also be present.
If only one eye is affected or cataracts
involve just a portion or one or both lenses, a dog will still be able
to see very well. But, if cataracts completely block both pupils,
blindness is the result. Symptoms of poor eyesight in dogs vary.
If they are in a familiar environment, they may move around so well
that it is almost impossible to believe that they can't see.
But, if they are moved to a new location they may stumble, bump into
things, act nervous, and not want to move around much at all.
A condition that is frequently confused
with cataracts is called lenticular or nuclear sclerosis. This
causes a fogging of the lens, but it is actually a normal age-related
change seen in older dogs and their eyesight is not significantly affected
Treatment and Prevention
To differentiate between cataracts,
lenticular sclerosis and other eye abnormalities, a veterinarian will
look into a dog's eyes using an ophthalmoscope. If cataracts
are the diagnosis, blood work and a urinalysis will also be run to rule
out diabetes as a cause and to plan appropriate treatment.
If a dog has only small cataracts that
are not significantly affecting his vision, treatment is not necessary.
If, however, a dog is blinded by his cataracts but his eyes otherwise
function normally, surgery to remove one or both of the cataracts is
an excellent option. This will require referral to a veterinary
ophthalmologist. Cataract removal is not appropriate for every
dog and owner. Medications that dilate the pupil may help some dogs see
around the cataract to a degree. Dogs with cataracts should be
monitored closely. In some cases, cataracts can cause eye inflammation
or increased pressure within the eye that is painful and needs to be
Unfortunately, no method of preventing
the formation of cataracts in dogs has been found, but wise breeding
decisions help to decrease this incidence in at risk breeds.
The Canine Eye Registry Foundation (CERF) maintains a registry of dogs
that have been examined by a certified veterinary ophthalmologist and
have been determined to be free of cataracts at the time of the examination.
The above is provided for information purposes only and should not be used for the diagnosis or treatment of any condition.
This information does not cover all possible variables, conditions, reactions, or risks relating to any topic, medication, or product and should not
be considered complete. Certain product or medications may have risks and you should always consult your local veterinarian concerning the treatment of
your pet. Any trademarks are the property of their respective owners.