Winter is a common time of the year when we see an increase in the number of cases of eye illness in sheep and cattle. Pink eye, New Forest disease, winter blindness are all common names we use for similar presenting conditions.

Infectious keratoconjunctivitis is seen in both cattle and sheep. It is an infection and inflammation of the surface and membranes of the eye. There are several causes, in sheep an organism called Mycoplasma conjunctivae is the most common where in cattle Moroxella bovis is the most common cause. However, there are several other causes, including Chlamydia and Listeria organisms.

The incubation period is often 2-3 days, mild infections result in watering of the eyes, progressing to painful, cloudy, inflamed eyes and can lead to ulceration and loss of sight in severe cases.

These organisms can be highly contagious and infected animals can carry the bacteria for several months without any symptoms, even after treatment and full clinical recovery. We can take samples and laboratories will identify which organism is present, but this rarely alters our treatment and advice.

These outbreaks can be very frustrating to control, especially in sheep flocks, where large numbers of animals can be affected, and treatments can be laborious and costly. We have plenty of effective antibiotics to treat these organisms and antibiotic resistance doesn’t tend to be the underlying problem. The duration of treatment is the key to successful management.

Because these organisms are carried by animals with no symptoms, strict biosecurity would stop new outbreaks. But this is almost impossible to achieve practically, as new stock-tups and replacement females are common movements on to holdings.

Infections are spread by close contact from animal to animal. We see an increase during winter due to higher stocking densities in winter housing, forage and concentrate feeding at feed barriers and racks. Indirect spread is also possible on shepherds’ hands or flies during summer months. Isolating affected animals will also reduce the infection challenge within a group but not eliminate it.

Once an outbreak is established within a group of animals it will tend to run its course until ‘herd/flock immunity’ is achieved. Outbreaks tend to vary in severity and duration, but treatment will be necessary in moderate and severe cases, at an individual animal level but sometimes whole group treatments are necessary. Delayed treatment will lead to animals in significant pain, ulceration of the eye and terminal blindness. It is essential to check affected groups daily to identify new cases and response to treatment.

Treatments options vary, topical penicillin-based ointments are licensed but may require retreatments due to duration of action. These are more useful for treating Moroxella infections in cattle than Mycoplasma infections in sheep. Subconjunctival injections are also useful in cattle, as they increase the duration of treatment while using smaller volumes of antibiotic.

In sheep, systemic treatments, where injectable antibiotics are used, often give the best cure rates. Longer acting preparations should be used to maximize cure rates. Penicillin-based antibiotics don’t treat Mycoplasma infections, which we see in sheep. Discuss the best treatment plan with your vet, including risk factors, biosecurity and treatment options.

Due to the painful nature of eye disease, consider using anti-inflammatories alongside antibiotics as this will reduce severity, symptoms and pain. Whole flock treatments may be necessary in some outbreaks, which can be costly and frustrating.

Entropion or in-turned eyelids

Another common eye condition we see especially in newborn lambs is in-turned eyelids. This is where the lower eyelid is folded in, and the hairs of the lower eyelid start to rub on the sensitive surface of the eye. This is painful, quickly resulting in trauma, infection and ulceration of the eye.

There is a very strong genetic heritable underlying cause. Breeds that tend to be affected are Texel, Beltex, Suffolks and Blue-faced Leicesters. Even crossing these sires in commercial flocks, we can see high incidences of entropion coming through in crossbred lambs.

Mild cases can be corrected simply by unfolding the lower eyelid repeatedly until the condition has resolved. Moderate or severe cases will require subconjunctival injections or sutures to prevent ulceration of the eye. Left untreated, entropion will lead to severe ulceration of the eye and even blindness, which has obvious animal welfare implications. Consider which tups are leaving lambs with entropion and not using them for breeding in future.

Pedigree bulls can also suffer from entropion, where the lower eyelid rubs on the surface of the eye. We tend to see this more in young bulls that are in show or sale condition. However, there is still a strong heritable genetic component. Early identification and treatment are recommended but surgery is sometimes needed in advanced cases for welfare reasons. We don’t recommend using these animals for breeding.