Keeping an eye on cattle infections.
Infectious Bovine Keratoconjunctivitis (IBK) more commonly known as "New Forest Disease" or "Pink Eye" is probably the most common ocular disease in cattle in Britain.
The main cause of this distressing and economically important disease is the bacteria Moraxella bovis, although other infectious and physical factors may increase severity and susceptibility to the disease.
These include viral and Mycoplasmal infections; flies especially face flies, ultraviolet light, dust and pollens.
The higher incidence of disease in summer is thought to be due to an increase in ultraviolet light and flies. The bacteria is maintained in a herd by carriers and spread by direct contact (head to head), and inanimate fomites (fence posts etc).
The incubation period is normally two to three days but can be longe. First signs of disease include a wet patch of tear staining beneath the eye and increased blinking.
The eye may have a hazy blue appearance due to swelling of the surface (corneal oedema), conjunctivitis is evident and within a couple of days ulcers appear on the surface of the eye. If these ulcers become large and under-run the surface tissue, rupture of the eye may occur leading to blindness in that eye.
Cases can recover spontaneously but many require varying degrees of treatment. In uncomplicated cases response is generally good but a white scar can often be seen on the surface of the eye.
The disease produces an immune response giving rise to at least partial protection which is probably constantly boosted by milder infections throughout life.
A number of other conditions may be confused with IBK in their early stages, these include IBR (Infectious Bovine Rhinotracheitis), Malignant Catarrhal Fever, Listerial Iritis (Silage eye), Squamous Cell Carcinoma (Tumour), trauma and a foreign body in the eye.
Treatment in mild cases is usually by topical antibiotic ointment applied into the conjunctival sac around the eye. These cases and more severe ones can be treated by sub-conjunctival injection.
This technique should only be carried out by a competent person. It places antibiotic locally into the tissue surrounding the eye at a high concentration and in severely painful cases may require local anaesthetic drops in the eye beforehand. In the most severe cases the eyelid can be stitched closed to protect the tissue while ulceration heals.
Prevention can be difficult but is based on keeping the infection at a distance. When a case is noticed the animal should be separated and treated. If infection is widespread the only action possible may be to inject all the animals in the group with long acting antibiotics. If you have a problem with this condition you should consult your vet, who can advise you on the treatment options.