Your pet’s eyes PDF Print E-mail
News - Rubrieke
Tuesday, 23 August 2016 20:19
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Dr Liesel van der Merwe is a small animal medicine specialist. Send her your questions: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .


Dr Liesel van der Merwe

As medical knowledge expands we are learning more about various aspects of our pets’ health. The field of ophthalmology is a growing one in veterinary science and a highly specialised aspect of care.
Animals are inclined to injure their eyes when they fight, such as a scratch from a cat, or when they run into bushes or thorns. The injury can be right through into the eyeball or mainly affect the eyelids.

All of these injuries require prompt medical evaluation for severity and if necessary, medical or surgical intervention if there is to be any hope of saving the eye. 

The eyes of our pets are also prone to trauma due to their conformations. Increasing numbers of congenital / hereditary eye defects are being identified in specific breeds. In these conditions, genetic testing is becoming available to test for carrier animals and remove these animals from the breeding population.

German shepherd dog are predisposed to a condition called pannus. The surface of the eye is irritated and damaged by dust, irritants and, most importantly, UV radiation and tries to protect itself by growing tissue across they eye.

Initially the tissue is pink with blood vessels visible, but it eventually becomes brown and pigmented. These animals require eye drops which control this inflammation. It is a lifelong medication, as we cannot control the cause.

The eyes of pugs and Pekingese, due to their bulging, are also prone to develop pigment on the corneas – pigmentary keratitis. In these flat-nosed (brachycephalic) dogs the eye sockets are often very shallow and their eyes bulge out and can easily ‘pop’ out of the socket if the animal is in a fight, bitten in that area or even just gets a big fright.

Depending on how much damage has occurred to the blood vessels and the muscles and the eyeball itself, these eyes can sometimes be replaced into the socket and regain normal function.

These flat-nosed dogs are also more prone to ulcers on the eye surface, because the eyes are more inclined to dry out. Corneal ulcers in cats can also occur due to viruses, such as herpes, as well as trauma and other infections.

Sometimes you can see a whitish patch on the surface of the eyeball where the top lining cells are peeling away. This is a very painful condition because there are a lot of nerves on the surface of the eyes.

In a response to pain the pupil will often constrict and be very small in that eye (iris muscles spasm) and the eyelids will also be pinched closed in a spasm. If left untreated, ulcers will eventually eat right through the cornea and cause the eyeball to rupture and could easily result in the loss of the eye.

Many dogs, for unknown reasons, may develop ‘dry eye’. This occurs when there is a decrease in tear production, usually due to immune damage to the tear glands. These animals must be uncomfortable, as we know this is not comfortable in people with this condition.

What we normally notice is a tacky yellow discharge. This is different to the normal discharge you would get with conjunctivitis, which is quite fluid. Your vet can test for tear production with a little litmus strip. These dogs also require lifelong treatment. In some cases drops can reverse some of the damage to the tear glands and improve flow.

The eyes are also indicators of systemic disease in animals, as with humans. Jaundice is often first noticed on the white part (sclera) of the eye. Sugar diabetes will often result in rapidly developing crystalline-looking cataracts. Animals with chronic inflammatory disease and cats with FIP will often develop cloudy inflamed eyes where the eye fluid is inflamed and the iris is reddish. This should cause your vet to look for one of several underlying diseases.

With ageing, dogs also develop what looks like cataracts. This slight grey discolouration of the lens is fibrosis and cataract surgery is generally not indicated. Veterinary ophthalmologists can remove true cataracts and replace lenses in exactly the same manner as human ophthalmologists – all with a fancy machine and only a needle puncture to gain access into the eye.

The opportunities and facilities for keeping our pets’ eyes in good health are thus available but may be costly due to the instrumentation required and the cost of the very fine suture materials. The successful recovery of any eye problem in your pets depends on early intervention.

Although our pets are tough, their eyes are just as sensitive as ours and should be treated with the same care

 

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