Pink-eye in Soay Sheep
Soay (and Boreray) occasionally fall victim to a most unpleasant and debilitating eye disease – Infectious Keratoconjunctivitis or Pink-eye.
The outbreak normally begins in a very innocuous fashion and sometimes shortly after lambing. Daily inspection of the flock at feeding time one morning revealed one young ewe who appeared to be squinting excessively and hanging back from the rest of the flock. As the weather is usually warmer and sunny at the time, it is easy to attribute this to the effects of strong sunlight and give it no further thought.
Within a couple of days, a second ewe presented with one eye completely closed and discharging profusely. Close examination of the affected eye revealed a totally opaque cornea. As an emergency measure, thinking that this was most likely the result of an injury sustained at the feeding trough, I applied some antibiotic ointment and vowed to summon the vet the following morning if there was no evidence of improvement. The next day it was obvious that there was a serious problem. The whole flock had become extremely nervous and many had streaming eyes. One ewe, already in poor condition after lambing, had collapsed in the middle of the field totally blind and was desperately calling for her lamb which had by now deserted her.
An injured sheep is a frightened sheep... be patient
There was little doubt that I needed to confine the worst affected animals and seek veterinary treatment but this proved to be anything but an easy task because, despite their lack of vision, they were acutely aware of my exact whereabouts in the field and were still competently able to evade capture. It took several hours to capture about 5 animals!
The vet duly arrived and initially suspected listeriosis but, in the absence of any other neurological symptoms, this was highly unlikely. Consequently, he offered a diagnosis of pink-eye and treatment was commenced on that basis. The treatment consisted of injections of antibiotics into the lower eyelids (to be repeated after 3 days), intramuscular injections of antibiotics and anti-inflammatories, plus twice daily applications of an antibiotic eye ointment.
Applying eye ointment to a blind and frightened sheep proved to be a particularly difficult and stressful task and, despite trying 3 different types of ointment (Opticlox, Aureomycin, Chloromycetin), I remained unconvinced that it was having any positive effect on the disease. The most alarming aspects of the infection were the speed at which it spread throughout the flock – with morbidity approaching 100% - and also the rapid progress of the disease once it became established. Some animals appeared to go blind virtually overnight. Older ewes, in particular those who had borne twins and lost condition, were undoubtedly the worst affected, with many suffering ulcerated corneas, whereas young lambs appeared to show little more than a watery eye for a day or so. Blindness and general discomfort were accompanied by severely depressed appetites and some required hand feeding as they were both unwilling and unable to find their food. With such a large number of animals affected it became impossible to isolate and treat every single case so only the most severe cases were selected for treatment.
A dark shed offers some comfort to a sheep with Pink-Eye
A dark shed offered them some relief from their photosensitivity and damp weather appeared to be particularly soothing to their sore eyes. Overall, treatment was generally unrewarding although as time went by I moved away from the eye ointments (except for ulcerated cases) and resorted to intramuscular injections of Terramycin which, although not effecting a miracle cure overnight, did appear to halt the progress of the disease and ease the discomfort. All the affected sheep have regained their vision – even those who received no treatment whatsoever – with only a couple being left with slight residual corneal scarring. It took many weeks to see any real signs of improvement but as their eyes gradually began to clear and their vision returned, so did their appetites and day by day they became much happier.
It is now November and there are still several cases grumbling on. It has become evident that the flock is still harbouring the causative organism and most of the new animals that have recently been introduced have contracted it. Fortunately, as the majority of them have been young lambs or shearlings, they have not been severely affected. All I can do now is be patient and wait for it to run its course….