You may recall that we had described the retina as the innermost and light sensitive lining at the back of the eyeball. Actually, one could define the retina as an extension of the optic nerve since the retinal membrane contains many nerve cells.
There can be several causes associated with the pathology of the retina. One can divide these conditions either as congenital (inherited: animal is born with the problem) or acquired. In the latter category would fall the following possible underlying causes: (i) traumas (blows to the head), (ii) metabolic disturbances, (iii) systemic infections, (iv) tumours, and (v) nutritional deficiencies. In dogs, the majority of retinal ailments are inherited.
In most of these cases, the nerve cells (light receptors) in the retina are destroyed, or the lining (membrane) becomes detached from the back of the eye. Various degrees of blindness would then occur, ranging from an inability to interpret light, to a blurred vision and even full blindness.
Let’s look at some of the known retinal maladies.
- Collie eye anomaly
This is an inherited trait that scientists have identified in the Collie and related breeds. The symptoms may be mild, and in fact, the condition could go unrecognised for years. There is retinal degeneration which may be accompanied by bleeding. Usually, it is not a severe condition and the animal sees relatively well, unless there is a detachment of the retina.
- Progressive retinal atrophy
As the name suggests, the problem gradually gets worse as time progresses. This too is a congenital (inherited) condition seen in several breeds of dogs including Poodles, Setters and Spaniels. Cats exhibit a similar malady. It is not a disease of the young dog, usually appearing when the animal is over five years of age, although it has been known to affect young Irish Setters and Collies.
Firstly, the dog loses its ability to see in the dark. This condition progresses later to total blindness.
A variation of this disease occurs when the central part of the retina is at first affected. This is an interesting ailment. The animal can see moving objects (peripheral vision), but has a problem with stationary objects (which are best seen by the centre of the retina).
- Retinal dysplasia
This is an inherited, local or generalized, incorrect/abnormal development of the retina. This condition could be consequent upon trauma (acquired), or as a result of a genetic (inherited) defect. Sometimes, damage to a puppy can take place when it is still in the mother’s womb as a result of a virus. A severe condition can develop, if there is a complete retinal detachment. Cataracts (see TPC of May 24, 2015) can accompany the problem.
- Optic nerve hypoplasia
This is a condition seen in kittens after their mothers would have had a bout with feline distemper (Panleukopenia). The damage occurs while the kittens are still in the mother’s womb. The kittens are born blind. In dogs, we find it as an inherited condition in miniature poodles.
Enough of this morbid subject.
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.