16/08/2020
Pink Eye Disease:
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Pink Eye or Infectious Kerato conjunctivitis is an infection of the eyes of cattle, sheep, and goats with a mixture of micro-organisms which include
⚜Moraxella Bovis,
⚜Mycoplasma species,
⚜Listeria monocytogenes and
⚜Chlamydia.
The infection occurs in animals of all ages but is more severe in young animals.
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𝐌𝐨𝐝𝐞 𝐨𝐟 𝐬𝐩𝐫𝐞𝐚𝐝
1️⃣Moraxella bovis is the organism primarily responsible for the severest form of the disease in cattle.
2️⃣When cattle are eating silage, Listeria may cause conjunctivitis, but less severe in than when caused by Moraxella.
3️⃣In sheep Clamydia is the most common cause. The disease is generally less severe in sheep and goats.
4️⃣Infection does not spread between small ruminants (like sheep and goats) and cattle since the causative agents of the disease for small ruminants differ from those which affect cattle.
5️⃣Spread by direct contact with infected animals, especially when animals are crowded together.
6️⃣In cattle, dry dusty conditions, shipping stress, irritants such as grasses and pollens, grasses contaminated by eye discharges, bright sunlight, lack of pigment in the eyelids and flies may increase disease occurrence.
7️⃣Flies also spread the disease in cattle.
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𝐒𝐢𝐠𝐧𝐬 𝐨𝐟 𝐩𝐢𝐧𝐤 𝐞𝐲𝐞
1️⃣The incubation period is usually 2-3 days but can be up to 3 weeks after infection.
2️⃣One or both eyes may be affected.
3️⃣The eye becomes watery, the lining under the eyelid becomes red and inflamed and the animal blinks repeatedly and diverts the affected eye(s) away from bright sunlight.
4️⃣A small unclear area appears in the centre of the eye. Within a few hours a faint haye appears which becomes denser. After 48-72 hours the whole cornea may be unclear, blinding the animal in that eye. If the eye is hazy white to blue this is due to accumulation of fluid. If it is milky white or yellow this is due to white blood cell infiltration and indicates severe infection.
5️⃣Blood vessels invade from the edge of the cornea.
6️⃣A small ulcer is apparent near the centre of the cornea.
7️⃣Continued active ulceration may cause the cornea to rupture.
8️⃣Appetite is often suppressed due to pain and visual impairment, milk yield is likely to drop and there may be loss of weight.
9️⃣Most animals slowly recover over a period of about a month, sometimes a small white scar remains. About 2% are left blind in the affected eye. In severe cases the eye becomes conical in shape, with ulceration at the tip. These eyes are liable to rupture.
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𝑶𝒕𝒉𝒆𝒓 𝒄𝒐𝒏𝒅𝒊𝒕𝒊𝒐𝒏𝒔 𝒄𝒂𝒏 𝒄𝒂𝒖𝒔𝒆 𝒊𝒏𝒇𝒍𝒂𝒎𝒎𝒂𝒕𝒊𝒐𝒏 𝒐𝒇 𝒕𝒉𝒆 𝒆𝒚𝒆,
so in every case, a close inspection of the affected eye is essential.
1️⃣Foreign bodies, such as grass seeds and awns can become stuck to the surface of the eye.
2️⃣Thorns can be embedded in the cornea.
3️⃣Spitting cobras can project venom into the eye
4️⃣Corrosive fluids and saps can inflame the cornea.
5️⃣Worms can live in the conjunctival sac.
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𝐏𝐫𝐞𝐯𝐞𝐧𝐭𝐢𝐨𝐧 𝐚𝐧𝐝 𝐜𝐨𝐧𝐭𝐫𝐨𝐥𝐥
1️⃣Avoid overcrowding of animals.
2️⃣Sick animals should be isolated and treated.
3️⃣Affected animals should have access to shade.
4️⃣Cleanliness in the cattle yards should be maintained in an effort to keep fly numbers to a minimum.
5️⃣Insecticides in the form of pour-ons may be beneficial.
6️⃣Recovered animals have an immunity lasting for about 12 months.
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𝐑𝐞𝐜𝐨𝐦𝐦𝐞𝐧𝐝𝐞𝐝 𝐭𝐫𝐞𝐚𝐭𝐦𝐞𝐧𝐭
Although many cases do recover spontaneously this is a potentially serious condition and therefore treatement should be considered before ulceration of the cornea leads to permanent blindness. A variety of antibiotics can be prescribed by a qualified veterinarian. These can be given by injection or in the form of eye ointment.
1️⃣Oxytetracycline is the drug of choice for systemic treatment as it is concentrated in corneal tissue. Two injections (20mg/kgIM) of long-acting oxytetracyline forumlation (-200mg/ml) at 72 hour intervals is the treatment of choice (as per the manufacturer's instructions).
2️⃣Ampicillin,penicillin, gentamycin and kanamycin can be injected into the eye, sometimes in conjunction with a corticosteroid such as dexamethasone, but this should be done by a skilled veterinarian.
3️⃣Eye ointment require frequent application to be effective, as often as three times daily. Oxytetracycline/polymixin B, gentamycin and erythromycin are effective. The ointment must be instilled carefully under both upper and lower eyelids.
4️⃣In severe cases the use of 1% atropine drops or ointment will prevent body spasms within the eye and reduce the likelihood of stickiness forming within the eye.
5️⃣If an ulcer ruptures the eye will collapse and shrink. In some cases there is continuing discomfort, pain and discharge due to ongoing infection. In many cases removal of the eye by a vet is the best option. This involves removal of the eye, leaving the eye muscles and remaining orbital contents intact.
