What You Should Know About Your Dog’s Eyes
The eye, in dogs, as in all animals, is the most specialized of the sensory organs. As such, it is highly sensitive to trauma, infection and disease, both acquired and hereditary.
Because dogs can't tell their owners when they are suffering irritation or pain in their eyes, the eye is an often overlooked area of trouble. Many a devoted dog owner has failed to notice his pet's eye trouble until it is so advanced that blindness results or the removal of an eye is necessary.
From the tiny Pekingese, whose slightly bulging eyes can become diseased because of inadequate protection, to the huge St. Bernard, whose drooping eyelids can catch and harbour bacteria which cause eye infection, many special breeds are particularly susceptible to certain types of eye disease.
Dog owners should be aware of some of the most common eye problems, which breeds are most likely to develop them, how they are treated, and, most important, how they can spot potential trouble while there is still time to safely treat or cure the disease.
Many a serious problem starts with an irritation or trauma to the eye, which causes inflammation. If a dog's eye becomes inflamed, the problem should be attended to immediately, as the problem can usually be treated if diagnosed in time. If inflammation is allowed to continue for too long, much more complicated problems can result.
What Can Happen To The Inflamed Eye?
For one thing, one of the most important protections the eye possesses - the ability to produce tears – can be interfered with or stopped completely. If the dog's eye no longer produces tears because the tear glands and ducks are inflamed, the dog can develop ulcers in the eye.
Your dog can also develop a condition known as keratitis, or inflammation of the cornea – a clear protective disc over the colored part of the dog's eye – gets inflamed, the white part of the eye often responds by growing blood vessels down over the injured cornea.
Of course, the dog will be temporarily or permanently blinded if the blood vessels are allowed to block light from entering the pupil, the small hole behind the cornea which lets light into the eye.
Infection, bumps or scratches on the eye, foreign bodies such as foxtails in the eye, and ingrown eyelashes are all common ways in which a dog's eye becomes inflamed. If a dog's eye become swollen, red, runs a lot, or if the dog rubs his eyes excessively, the owner should see a veterinarian before the condition becomes serious.
Most dog owners, if not all of them, never consider looking into their pet's eyes for signs of illness, especially dogs with hair over their eyes.
There is a myth that cutting the hair away from a dog's eyes will cause blindness, but, in fact, a dog's eyes are much less likely to become diseased if the area is free of air. Dogs with hair growing over their eyes should either have it trimmed or pinned back.
The most serious problem that can result from an inflamed eye is a condition called glaucoma. Glaucoma occurs when the fluid pressure within the eye gets too high. It is caused when the passage which drains the fluid out of the pupil becomes too narrow to allow fluid to pass. Glaucoma can and does cause blindness if not treated immediately. Inflammation of the eye is one thing which can cause the drainage passage to become swollen shut.
Glaucoma can also be caused by a tumor in the eye, or by an inherited condition peculiar to certain breeds, in which the angle of fluid drainage in the eye is too narrow at birth. Wire-haired Terriers, Basset Hounds, Cocker Spaniels, and Malamutes are more apt to be born with this abnormally narrow angle of drainage than most dogs.
If glaucoma is not treated immediately by alleviating the extremely high pressure of the eye fluid, a great deal of pain and eventual blindness will result. Owners, especially of the breeds mentioned, should watch for redness in the white part of their dog's eyes, dilated or large pupils, and rubbing of the eyes by the dog. If the symptoms are treated early, blindness can be prevented.
Check The Eyelids
Many eye problems require medical tensions caused by eyelid abnormalities. These are problems the dog is born with, and again, certain breeds are especially prone to certain abnormalities. The two most common types of eyelid abnormalities are ectropian, in which the eyelid turns out, and entropian, in which the lid turns inward toward the eye.
Bloodhounds, Basset Hounds, Cocker and Springer Spaniels, St. Bernards and Akitas are some of the breeds most likely to suffer from ectropian. Entropian is often seen in Chows, Bulldogs, Doberman Pinschers, Setters, Golden Retrievers, Poodles, and St. Bernards.
Both conditions can cause infection and inflammation of the eye. They are most commonly corrected surgically. The surgery is a cosmetic one, for the purpose of correcting the confirmation of the dog's eyelid. The part of the eyelid which droops or turns inward is removed, making the eye normal. It is not a complicated procedure, and one which in nearly every case solves the dog's eye problems.
Many eye diseases in dogs can be successfully cured surgically if non-surgical treatments do not help. In the condition in which the tear glands and ducks are not producing tears, for example, a medication is put into the dog's food in the form of drops.
If there is any function at all left, the medication will stimulate the glands to again produce tears normally. If the medication does not work, an unusual and creative operation is sometimes performed, whereby a duct of one of the dog's salivary glands is moved so that it empties out of the eye instead of the mouth.
The saliva moistens and protects the eye just as the tears are supposed to. Logically enough, Pavlov's theory works with slight alteration – a dog who has had such an operation cries when his appetite is stimulated!
If an ulcer has resulted from the dryness and inflammation of the eyes, or from some other irritation or trauma, medication is again tried initially. Especially if the ulcer is a superficial one, antibiotics usually heal it.
If the ulcer is a deep one or has punctured through the cornea into the eye itself, another innovative type of surgery is performed. The ulcer is covered with a truly organic “bandage” - the dog's own third eyelid, or a flap from the white part of his eye. The bandage is left on for several weeks while antibiotics are used to heal the ulcer. It can then be removed with a snip or two of the stitches holding the bandage in place.
Cataracts in Dogs
Owners of old dogs often notice a condition commonly referred to as cataracts – a bluish white film over the eyes. Actually, the condition is a thickening of the lenses, which is a function of age. It usually begins to be noticeable in dogs about 10 years of age, and progresses slowly. It does not usually affect the dog's vision until the dog becomes quite old.
True cataracts are a total thickening of the lenses, so that light cannot come through the pupil and sight is lost. Certain injuries and infections can cause cataracts, and the condition is sometimes a sign of diabetes.
There is a disease, juvenile cataracts, in which cataracts appear at a very young age (as early as 1 year old), first in one eye and then in the other.
This is an inherited disease, seen most commonly in Irish Setters, Afghans and Old English Sheepdogs. The only way to prevent blindness is to surgically remove the lenses. Dogs are nearsighted anyway – they can't adapt their vision to distances – so the removal of the lens is something they can live with quite comfortably without much noticeable difference in eyesight.
How To See The World Through a Dog's Eye View
Like tourists who assume everyone speaks English, or should, it is second nature to us to think that the world looks pretty much the same to all creatures, great and small, including our dogs. For example, we rarely give much thought to the optical processes that turn light into vision; we assume that our visual version of reality is reality.
Even those of us who wear glasses fall into this way of thinking. Glasses bring things back into focus so they once again look like they are. If those people who run around staging role-playing seminars on multiculturalism for business executives were to do the same for multi-species, I would suggest as the first group exercise they get everyone down on the floor with their eyeballs about six inches off the ground. Simply by virtue of visual perspective, the world looks very different to a Chihuahua.
Dogs also differ from humans in their ability to focus on near objects, to perceive and distinguish detail, and to see contrasts between light and dark. Some of these differences are relatively minor, but some must result in a highly altered version of reality. The most remarkable feature of the human eye is its extraordinary power of "accommodation." The lens
in a normal eye, when relaxed, is of just the right thickness and curvature to bend incoming light rays from a far distance (equivalent to the setting of "infinity" on a camera lens) so that they converge in sharp focus upon the retina at the back of the eye.
If the lens were incapable of adjustment, the light rays from close objects would end up converging at an imaginary point well behind the retina; the result would be a grossly blurred image striking the light-sensitive cells of the retina. But by squeezing the lens with muscles that are under unconscious control, we can make the lens thicker and alter its curvature, bringing close objects into proper focus. The greater the squeeze, the closer to our face is the focus.
In young children, the eye's lens is capable of adjusting by as much as 14 diopters, an optical unit used in describing the power of lenses (and in prescribing eyeglasses). That degree of accommodation corresponds to being able to focus on everything from infinity to an object less than three inches away. By way of comparison, eyeglasses with a power of 14 diopters would look like the proverbial Coke bottle bottoms. (Most glasses for correcting nearsightedness in humans run about 1 to 5 diopters.)
Dogs have a much more limited power of accommodation, generally not more than 2 or 3 diopters, which means they can focus on close objects only if they are no nearer than a foot or two. Anything closer than that will unavoidably be a blur. That may well explain why dogs generally try to sniff or touch objects at close range: they simply cannot see them very well. If the relaxed lens normally brings a distant object's image into focus behind the retina, the result is hyperopia or farsightedness.
Tearstains in Dogs
Some dogs, especially Poodles, Maltese, and toys whose faces are white, sport darkly stained facial hair along the inside corner of their eyes. The stain is caused by tears, which should collect in the tear ducts but instead flow onto the face. There are several reasons the tear ducts may not be draining all of the tears secreted.
The ducts may be obstructed or too narrow to do their job properly. In some cases, the ducts themselves are properly formed and functional, but the tear flow itself is too excessive. This may be caused by conjunctivitis, allergies, entropion, infection of the Harderian gland, or an infection of the third eyelid.
If you notice a new stain, or a stain that seems to be getting worse, consult your veterinarian; he or she will need to determine the underlying cause of the problem. If an infection is triggering the staining, antibiotics will be prescribed. Surgery may be recommended to remove the third eyelid, increasing the area into which tears can flow.
How to Get Rid of Tearstains on Dogs:
1. Keep the hair clipped close to the face.
2. Mix two teaspoons of hydrogen peroxide in twenty teaspoons of lukewarm water. Gently rub some of the solution into the stained hair, taking pains to prevent getting any of it in the eye itself.
3. Carefully rinse with lukewarm water.