New Forest Eye in Cattle

Also know as Pink Eye,(Infectious Bovine Keratoconjunctivitis, IBK)

What is New Forest Eye?

New forest eye is an eye infection caused by Moraxella bovis. Cattle can become infected via bacteria from the environment and from bacteria from ‘carrier cows’ which are infected but have no obvious eye disease. It is probably the most common eye disease of cattle being seen in any age from calves to adult cows. However, cows can become, at least partly, immune as the disease is much more common in youngstock and yearlings than in adults.

The highest rates of disease are seen in low lying, wet pastures with a high fly population. The fly acts as a mechanical vector of infection, spreading the bacteria as it feeds on the secretions from the eye. Other factors linked to increased disease include the length of grass and dusty conditions. Both of these are associated with eye damage which allows the bacteria to attach to the eye and start multiplying.

Clinical Signs

Early signs:

1) Excess tear production, with staining on side of face

2) Dislike of bright sunlight

3) Closed eyelids

Later signs:

4) Surface of eye becomes cloudy and white

5) An ulcer (a loss of the surface of the eyeball) develops, usually in the centre of the eye

6) This may rupture, with loss of the lens and sight in the eye

7) This condition can be extremely painful, resulting in lower weight gains

In most circumstances more than one animal is affected, so if you notice a case it is always worth checking the rest of the group. When you do so, you are likely to see cattle at all stages of the disease.

Diagnosis

If you have seen New Forest eye before it is easy to recognise. If you haven’t, get veterinary advice. The disease that is most commonly confused with New Forest eye is bovine iritis (silage eye). In this disease the eye is much less ‘pink’ as there is no conjunctivitis in most cases.

Treatment

There are three options for treatment. The cheapest and simplest is topical antibiotics. Powders are available but ointment is far more effective as they last much longer (up to 48 hours). Topical ointments are best used in early cases before ulcers get too deep.

In later cases injected antibiotics are essential. These can be given either into the muscle or vein or into the conjunctiva (the membrane surrounding the eye). Subconjunctival antibiotic injections can be very helpful but should only be given by a veterinary surgeon.

Many mild cases will self heal, but early treatment prevents the scarring that can occur even in mild cases and reduces the spread of infection to other cattle, so identifying and treating early can greatly reduce the cost of New Forest eye.

Prevention

Prevention is based on good fly control. There are two sorts of prevention chemical and management.

Chemical:

1) Ear tags – Can be effective if fly numbers are moderate

2) Pour-ons – Need applying regularly to be effective.

Ask your vet for advice as to the best regime to use on your farm.

Management:

1) Pasture management: Keep susceptible cattle away from areas where conditions are less favourable for flies, such as near wet woodlands.

2) Check cattle frequently (at least twice daily) during the risk period. Look out for early signs of tearing and partial closure of the eyelids

Article by Richard Laven PhD BVetMed MRCVS