'Opthalmia' 'pink eye' 'aansteeklike blindheid'Friday, 5th June 2020
By Dr Mackie Hobson
The proper name is infectious keractoconjunctivitis which is the inflammation of the cornea and conjunctiva. Pink eye affects Angora goats and sheep. The bacteria implicated (Chlamydophila, Mycoplasma or Moroxella) cause the condition to be highly infectious and easily transmitted between infected goats. The Chlamydia organism is the same organism that can cause enzootic abortions in ewes.
The causative bacteria(s) can be identified by taking a swab from the effected eye and sending it to a veterinary lab.
The frustration of treating and controlling the spread of ‘infectious opthalmia’ when introduced onto the farm is enough reason to follow a quarantine procedure.
Pink eye is usually seen in summer and often more in younger goats. The incubation period is anywhere between 3- 21 days.
Pink eye tends to occur as an outbreak in a flock of Angora goats. The causative bacteria is often introduced by purchased goats and hence the importance of a quarantine procedure on each farm. However the organisms may persist in resistant, carrier animals.
Dry, dusty conditions and irritants such as flies tend to predispose or exacerbate the disease. Flies or dust can carry the bacteria to the eye. Close contact such as crowding and goats at feed or water troughs and on lands will aid the spread of the condition.
Affected goats blink repeatedly and have an aversion to bright sunlight. The face below the eye may be wet due to tearing. The membranes of the eye appear red and inflamed. The eyes become cloudy or opaque and an ulcer may develop. The condition is painful and may affect one or both eyes. Pink eye can cause temporary blindness in affected animals and permanent blindness in severe cases.
A large amount of research has been conducted in Australia on sheep due to the problem of pink eye in sheep being transported by ship to the Asian countries.
The most effective treatment was found to be oxytetracycline injections at dose levels of 20mg/kg which is repeated after 4 days.
Farmers have found that by also squirting some tetracycline (off licence) into the eye as well as the intramuscular injection at the doses above was effective. Sometimes, sub-conjunctival injections of long-acting oxytetracyclines or penicillin are given.
Other treatments to be effective include terramycin ointment or intra-mammary preparations placed directly in the eye on a daily basis. Powders have been found to be irritant and in certain cases can worsen the clinical signs.
Before applying medicine to the eye, the goat's face should be cleaned and the debris around the eye(s) should be removed. Gloves should be used when affected animals are handled as potentially humans may become infected.
Using fly repellents around the face will also help control the disease. Affected animals should be isolated from the rest of the flock to prevent spread of the disease. They should be housed in a clean, dry and shady place.
Despite intensive efforts, treatment may have little effect on the course or severity of the disease and hence the frustration in getting the condition under control on the farm. Severely affected animals may take longer to recover. Recovered animals have resistance for varying lengths of time. It is possible for them to become re-infected, as acquired immunity is not strong or long-lasting.