HUSK, or parasitic bronchitis, is the most common cause of breathing problems in cattle at pasture and begins in June increased throughout the summer months before peaking in September, writes NADIS vet Richard Laven.

Husk occurs as a result of lungworm infection.

Cattle develop husk after eating forage contaminated with the infective larvae.

Once in the gut they migrate through its wall and a few weeks later they reach the lungs where they begin to lay eggs.

Although Husk is primarily a disease of young stock, it is becoming more common in adult cattle.

Clinical signs range from a mild cough to severe persistent coughing with marked difficulty breathing.

Husk can even result in death.

Other signs include weight loss and, in adult cattle, large falls in milk yield.

Diagnosis is based on these clinical signs and veterinary examination.

It may be confirmed by post mortem examination or by finding larvae in dung or saliva.

Treatment with a suitable wormer is essential and the whole group should be dosed.

Severely affected cattle will also need veterinary treatment with other drugs.

Prevention is best achieved by oral vaccination.

The vaccine course must be completed at least two weeks before cattle are turned out and should include all healthy young stock.

Lungworm can also be controlled using either a regular worming regime, sustained release boluses or repeat dose boluses.

However, if the worming regime is too effective, no immunity develops and cattle can develop husk in their second or even third grazing season.

l NADIS, a network of veterinary practices and colleges which monitors animal disease in the UK.

It is sponsored by the Milk Development Council, Elanco Animal Health and Schering Plough Animal Health.