The arrival of sunshine and silage also heralds the arrival of the fly. In cattle, infectious keratoconjunctivitis (pinkeye) and dry cow mastitis (DCM) are both spread by flies. Flystrike (maggots) is our main concern in sheep.

In the suckler cow, lameness may be the first sign of DCM. She can appear to limp as she tries to avoid her leg rubbing against the sore and swollen quarter. Usually, the quarter is lost and treatment is directed at returning the cow to full health and protecting the unborn calf.

Pinkeye is a painful bacterial disease that can lead to reduced weight gain in cattle. Initially, we have a watery eye followed by a white and sometimes ulcerated surface of the eye. While most eyes recover, with some scarring sometimes, all sight is lost in the eye.

Early treatment and isolation can help slow the spread of this disease and improve the outcome of an individual animal. Topical antibiotics and eye patches can be used. The eye discharge is highly infectious and can be spread by flies and long grass. Dust and sunlight make it worse.

Flystrike in sheep can be prevented by using one of the modern fly repellents which provide season-long cover. Watch meat withdrawal times if using them in animals which are close to finishing for the factory.

Dagging (removal of wool from around the tail and back end) helps decrease flystrike risk. Faecal sampling is advised, especially if diarrhoea is present, so a targeted parasite treatment plan can be used in your flock.

Fly control can be achieved by using fly tags or pour-on fly repellent. Cows’ teats have no sweat-producing glands, so these products don’t get secreted on to the teat surface. Timing of application is important as these products have varying durations of action.

Routine fly control can help prevent diseases that have lifelong consequences.

Rachel Brown works at Moy Veterinary Clinic, Barrett St, Ballina, Co Mayo, part of XLVets. XLVets is a group of progressive practices that are working together to achieve a better future for agriculture and veterinary in Ireland. For further information, go to www.xlvets.ie.