We last dealt with conjunctivitis, an inflammatory process of the membrane which covers the inner side of the eyelids and part of the surface of the eyeball, (Pet Corner January 4, 2009).
Today, we shall discuss some more diseases of the cornea.
(keratitis, corneal opacity)
In this condition, the clear part of the eye has an inflammatory process (keratitis). Irrespective of which type of keratitis emerges, the result is the same, namely that the cornea loses its transparency and becomes dull and cloudy and, eventually, totally opaque.
It may be of interest (to those who crave knowledge) to describe how this transparency and translucence of the cornea develop into opacity. The cornea is not fed/nourished by blood. If it were, then light could not pass through to the deeper recesses of the eye. The cornea is fed by lymph, which is transparent. It is the coagulation/clotting of this lymph which leads to cloudiness. Finally, blood vessels grow into the affected area and pigmentation develops which totally precludes light penetration. For all practical purposes, the animal is then blind.
Initially, the keratitis could be on the surface of the eyeball. This is usually the result of some mild injury (external violence, foreign body) on the cornea. In fact, because the injury is mild, it may not be detected at an early stage. There may be some production of tears or a pus-like discharge associated with superficial (surface) keratitis, and this may be wrongly diagnosed and treated as a case of conjunctivitis (Pet Corner, January 4). With keratitis, pain is more intense and is accompanied by squinting and the avoidance of light.
Attempt to allay the pain and discomfort. Applying warm compresses to the outside of the eye can do this. Clear away discharges that may have accumulated. To do this, you may use cotton wool dipped into warm salt water (one dessertspoonful of salt to a pint of warm water).
If a foreign body is involved, attempt to remove it. Take the corner of a clean handkerchief, wind it to a point, and lift the offending body out with it. You could also smear some sugar-based syrup on a finger and brush the latter quickly across the eyeball. These are simple first aid measures. If they are unsuccessful, you need to see your vet.
‘Blue eye’ (Interstitial keratitis)
You may recall that we had discussed (very superficially) the structure of the various components of the eye. We had said that there were, in some instances, several layers of cells making up the specific tissue of any one part of the eye. In the case of ‘blue eye,’ some of the deeper layers of the corneal tissue become inflamed. This results in a greyish film (we use the term ‘blue’) over the clear part of the eye. Very often this ‘blue eye’ is associated with canine infectious hepatitis (Pet Corner, October 5, 2008) which is caused by a virus, and which can be vaccinated against. Unfortunately, on the odd occasion, the vaccine itself can precipitate the ‘blue eye’ condition. However, if we have to choose between giving the dog a permanent immunity to canine infectious hepatitis and having a temporary discoloration of the cornea, it is obvious that we should go for the vaccination. The ‘blue eye’ problem corrects itself
in two to three weeks.
Practically all ‘cloudy eye’ (keratitis) conditions stem from a mechanical injury. Secondarily, germs invade, and we resort to antibiotics. Antibiotics will act against bacteria, but not against fungi or viruses. Consequently, a constant and prolonged application of antibiotics, while keeping the bacterial numbers down, may allow a fungal infection to emerge and proliferate.
If we are confronted with a ‘cloudy eye’ problem which will not go away after continuous use of antibiotics, then it may be wise to resort to help from the microbiology laboratory. There are now several such labs functioning. They can determine whether we are dealing with a bacterial or fungal keratitis.
Finally, and in passing, I should refer to a keratitis condition which occurs only in adult (over two years of age) German Shepherds, affecting both eyes. Here we find a pink, opaque membrane (comprising blood vessels, pigment, and other connective tissue) growing across the cornea. It leads to permanent blindness, especially since there is no reliable cure.
Such dogs should not be allowed to mate, since it is believed that the ailment has a genetic origin. We don’t want to perpetuate this abnormalcy.
Anyway, I have never encountered this malady in Guyana. Perhaps, German Shepherds with this inherent problem never arrived on our shores.
Please implement disease preventative measures (vaccinations, routine dewormings, monthly anti-heartworm medication, etc) and adopt-a-pet from the GSPCA’s Animal Clinic and Shelter at Robb Street and Orange Walk, if you have the wherewithal to care well for the animals. Do not stray your unwanted pets, take them to the GSPCA’s Clinic and Shelter instead. If you see anyone being cruel to an animal, or if you need any technical information, please get in touch with the Clinic and Shelter by calling 226-4237.