I often take calls from farmers who have found blind sheep, and have had a few inquiries in recent weeks about pinkeye. In broad terms, blindness in sheep is usually due to either an issue with the eye itself, or a neurological problem (in response to this comment, a cocky once told me that ALL sheep have a neurological problem).
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Pinkeye in sheep is due to an infection (several different bacteria can be involved), but symptoms can look similar to physical trauma caused by grass seeds, for example.
Pinkeye in cattle is often a predictable problem, with some herds experiencing regular outbreaks in young stock in late summer or autumn. Pinkeye in sheep seems to turn up more sporadically, so many sheep producers may not have seen cases before.
Prolonged dry conditions and dry, stalky feed can contribute to a pinkeye outbreak by physically irritating the eye this has probably been a factor in recent cases in our region.
Supplementary feeding can also increase the risk due to irritation from dust.
Pinkeye in sheep is due to an infection. Symptoms can look similar to physical trauma caused by grass seeds.
- Nigel Gillan
In pinkeye cases in sheep, the eye usually looks blue/white and cloudy. The membranes around the eye are inflamed, and there may be some discharge or tear staining on the face. It can look slightly different to typical pinkeye in cattle.
Mild cases of pinkeye in sheep will often resolve on their own. More severe cases will usually benefit from treatment with antibiotics and pain relief - your vet will be able to advise on the best approach.
Powders or aerosol sprays are sometimes used, but regular administration is usually impractical, and frequent yarding to treat affected sheep can simply cause further irritation from dust or crowding.
Another (much less common) cause of blindness in sheep is overdosing with closantel drenches. When given according to label dose rates closantel is a safe and useful drench, but overdosing can lead to irreversible blindness.
The eye may look normal, but if you look closely the pupil is dilated (wide open) so that the eye looks black. As with any drench, its important to use the right dose rate to avoid toxicities.
The other broad cause of blindness in sheep is neurological disease. Any disease affecting the brain can lead to blindness pregnancy toxaemia (preg tox or lambing sickness) and PEM (vitamin B1 deficiency) are two examples that I see occasionally.
In these cases, the eye itself will look normal, and other neurological symptoms (like lethargy, tremors, or convulsions) may be present. Management and treatment depends on the underlying cause, so its best to have any problem properly diagnosed.
