Cataracts are basically any opacification of the lens of the eye. This cloudiness can range from tiny punctate cataracts (similar to a piece of dirt on your glasses) to fully mature cataracts, which give the eye a whitish appearance and block vision, causing blindness. I might add that there's a common old age change in the lens called nuclear sclerosis which can give the pupil a bluish/whitish cast, but does not interfere that much with vision.

The causes of cataracts are numerous. There are some that have a genetic basis -- juvenile (puppy) cataracts in Miniature Schnauzers is one example and cataracts in adult Labrador Retrievers is another. Cataracts can also occur secondary to another health problem, such as diabetes mellitus, or from trauma to the eye. Some cataracts appear, develop only so far, then stop; others progress to the vision-limiting "mature" cataracts.

With such a wide range of clinical situations, it's a good idea to have your dog examined by a board-certified veterinary ophthalmologist if there's a cataract present. Depending on the breed of your dog and the appearance of the cataract, an ophthalmologist can often advise you as to whether this might be an hereditary cataract. He or she can also make judgments on vision and whether cataract surgery makes sense for your dog.

Right now, surgery is the only real treatment for cataracts. Cataracts which are not progressing and have not interfered with vision much should be left alone. And even if your dog has a mature cataract in one eye, the other eye may be good enough that overall vision is satisfactory. Surgery may not make much sense in that case.

Before a veterinary ophthalmologist schedules surgery on Fido's eye, there are some preliminary tests. This is an involved, delicate surgery and requires that your dog be fairly deep under anesthesia -- the eye should not move at all while the surgeon is working. To that end, your pet will have blood screens to, hopefully, rule out any problems with anesthesia (and possibly an EKG to check the heart as well). Diabetic patients must be very controlled; anesthesia and surgery are even bigger stresses for them.

The dog must undergo some specific eye exams, as well. The doctor may perform an ocular ultrasound to look for other underlying problems and will want to do an electroretinogram (ERG). The retina can't be examined in the normal way since the cataract is blocking the exam, so the ERG is needed to see if the retina is functional. If the retina isn't normal, then removing the cataract won't restore any vision. It doesn't make sense to do a surgery that won't improve the condition of your dog.

As mentioned, during surgery, Fido will be well anesthetized and will probably have a temporary muscle paralyzing agent, as well. The ophthalmologist will work with an operating microscope since it's such a small and delicate area. Many times, a prosthetic (artificial) lens will be placed in the eye. That can improve vision even more than just removing the cataract.

Post-operatively, you, as owner, will be busy. Fido will most likely be sporting an Elizabethan collar to protect this sensitive area while it heals. There will be both eye drops (possibly as often as 6 times a day) to guard against infection and inflammation, and very often, systemic medications (pills), as well.

Initially, there'll be frequent checks to insure that all is going well. Eventually though, the medications will taper off and you'll be down to annual checkups with the veterinary ophthalmologist. The success rate runs about 85% to 95% which is very good, considering many of these patients are older to begin with.

Hopefully you'll never need this information, but if your dog should develop a cataract, don't hesitate to contact your veterinarian and arrange for a visit to a veterinary ophthalmologist. There are some ophthalmologists in private practice, though you'll probably end up traveling to the nearest veterinary college.