Pink eye in cattle
Pink eye results in economic losses when it occurs as an outbreak due to reduced weight gain or even weight loss in calves. Affected animals suffer considerable pain and distress. It is a common, highly contagious eye disease of cattle of all ages, particularly calves.
The primary cause of pink eye is Moraxella bovis, but the severity of the disease is influenced by the presence of other micro-organisms. Flies are mainly responsible for the spread of infection, while carrier animals are important reservoirs of infection within a herd.
Damage to the cornea, most commonly due to the effects of UV light, dust or pollen, is the main predisposing factor. Pink eye most commonly occurs in dusty conditions over the summer, but can occur at any time of the year. Other factors may be involved including increased physical damage due to seed head in pasture. White-faced calves are more prone and stocking rate can have an effect.
Affected animals dislike light, blink and weep a lot from one or both eyes. Initially the lesions are central corneal ulcers that rapidly enlarge and are invaded by blood vessels from the white of the eye - hence the name pink eye. The ulcers may become purulent. Healing leaves a scar on the cornea that can permanently impair vision. In a small number of cases, the cornea can rupture.
Treatment involves the use of antibiotics. Severe cases benefit from covering the eyes with a patch or by temporary surgical closure of the eyelids.
Pink eye is best prevented by controlling flies and environmental predisposing factors. Vaccination is possible as a preventative measure or, less effectively, for the management of an outbreak of disease.
Pink eye has a long incubation period - up to 3 weeks from exposure to showing signs, though it can be as short as 3 days. Some animals can be incubating the disease before or at the time of vaccination or soon after. Some will be exposed to an infective dose before development of a sufficiently strong immune response.
Mixing of animals with other mobs, be it clinical cases, healed eyes, or apparently unaffected animals from mobs where active infection has been present, is best avoided, even if un-infected mobs have been vaccinated.
Vaccination is best completed 3-6 weeks before challenge, which is usually late spring/early summer. Vaccination can be from one week of age and consists of a single-dose vaccine. As with any vaccine, there is a range of immune response between individuals, with some animals having less protection than others following vaccination. Allow calves to settle in for a few days before vaccinating and keep new animals separate from other stock for at least 3 weeks.
For prevention, control and treatment options of pink eye in your herd, contact your vet at Totally Vets.
