Weather conditions prompts lungworm disease warning

The lungworm threat extends late into grazing season, and cattle are at risk of the production-limiting disease
The lungworm threat extends late into grazing season, and cattle are at risk of the production-limiting disease

Farmers have been told to remain vigilant for signs of lungworm disease in cattle following this summer's dry weather and recent heavy rain.

Recent weather conditions are likely to lead to late outbreaks of lungworm disease in grazing cattle, caused by the Dictyocaulus viviparus parasite.

The disease, often referred to as Husk, can cause significant production losses and increased costs for farmers.

Animal health company Boehringer Ingelheim is now urging cattle farmers to remain vigilant for signs of the disease.

Lungworm larvae excreted onto the pasture early in the grazing season are likely to have remained locked within dungpats while temperatures were very high, according to Sioned Timothy, Ruminant Technical Manager at Boehringer Ingelheim.

“While larvae on pasture will die in prolonged hot, dry weather, the residual moisture within dungpats means that larvae excreted recently are likely to have survived,” she explained.

“Now that we have had widespread rainfall across the country, we expect to see larvae complete their development and disperse onto the pasture to infect grazing animals.”

'Difficult to diagnose'

Heavy rain is very effective at distributing infective larvae from pats, but the pilobolus fungus that grows on dung also plays an important role in this; propelling larvae up to three metres as it expels its own spores.

While July, August and early September are usually the peak months for lungworm infections and cases of clinical disease, this year infections may crop up later into autumn and, depending on the weather, as late as November.

The problem for farmers, and vets, is that lungworm can be difficult to diagnose at an early stage and may not be spotted until a full-blown outbreak occurs, according to Ms Timothy.

Clinical signs from late-season infections may not be observed until cattle are housed, and complicating matters further, coughing can be confused with other respiratory diseases, which can occur shortly after housing.

'Severe'

Sudden outbreaks of lungworm disease can be severe and, if the early signs of infection are not identified quickly, significant production losses – of up to £145 per animal - could occur, including death in the worst cases.

Lungworm should always be considered as a potential cause of coughing in cattle. Farmers should not wait until the whole herd is unwell, but seek advice from their vet early in the course of disease to minimise long-term impact.

Other signs that can indicate lungworm infection include rapid loss of condition and sudden milk drop in lactating animals.

Dairy cows will often spend less time grazing, and more time resting. Their water intake is also likely to be reduced. Severely affected cattle will typically stand with head and neck extended in an ‘air hunger’ position.

There is an increasing trend for adult cattle, as well as youngstock, to be affected by lungworm disease.

Lungworm

Immunity to lungworm is short-lived, and if natural boosting through low-level exposure to larvae does not occur, animals may be rendered susceptible to disease when the number of larvae present on the pasture increases, as may be the case this season.

However, even immune animals can succumb to disease in the face of high larval challenge.

If lungworm is diagnosed, cattle should be treated immediately with a wormer that quickly removes lungworm and prevents re-infection, to allow lungs to recover, according to Boehringer Ingelheim.

The company said it is vital that the whole herd is treated as some infected animals will not show obvious clinical signs at the same time but will still suffer performance losses.

A vet should assess severely affected individuals, as they may need additional treatment to treat pain, inflammation and any secondary infection.