Beware of summer mastitis: What British farmers need to know

“The most important thing to do is to graze susceptible animals in exposed fields away from trees and open water where flies breed.”

Once a case of summer mastitis occurs, the level of infection carried by flies increases dramatically as they land on an infected area and then fly off to a neighbouring cow.

“The best way to avoid this is to bring all infected cows indoors, which will be necessary in any case if they are to be treated,” says Dr Lowman.

How to prevent flies settling on cattle

• Consider the use of teat sealants. It is essential the end of the teat is carefully cleaned and disinfected before the tube is inserted
• Stockholm tar, an old-fashioned remedy, can be used to form a physical barrier over the end of the teat. However, it is difficult to apply and to be effective and needs replacing weekly; an alternative is to use polyurethane varnish as a teat dip
• There are a number of spray products on the market aimed at deterring or killing flies
• Insecticide eartags can be used, but for best effect they need to be applied in early spring to kill as many flies as possible while numbers are relatively low
• A naturally occurring sulphur compound in garlic seeps out of the animal’s pores and sweat glands and acts as a repellent to flies and other biting insects