Vaccinating cattle against lungworm can help create herd immunity, providing the treatment is administered correctly.
The Control of Worms Sustainably (COWS) group says farmers need to be buying vaccine now to achieve herd immunity, and says the oral treatment should be given twice, four weeks apart, with the latter dose given two weeks before turnout.
Dr Catherine McCarthy, who has completed a PhD on the epidemiology of lungworm at the University of Liverpool, says: “The vaccine creates short-term immunity until longer lasting cover can develop naturally by cattle picking up lungworm larvae while grazing.
“Cattle to be considered for vaccination include first season grazing calves, cattle not vaccinated before, bought-in cattle with unknown vaccination status, and cattle which have not been exposed to normal lungworm levels in their last grazing season.
“Newly vaccinated cattle should also be placed onto lungwormcontaminated pasture at turnout, if possible, to help boost immunity generated by the vaccine.”
Cases are normally seen from August to October and infection is caused by the lungworm parasite, which completes its lifecycle in the lungs of its host.
Clinical signs could include coughing and rapid breathing and, with the disease becoming increasingly common in adult cattle, not just youngstock, COWS estimates an overall cost of an incident per adult dairy cow at £140, alongside loss in milk yields of up to four litres per day.
The number of cases is thought to be increasing, particularly in Scotland and northern England, as a change in climate is allowing farmers in the north of the UK to turn cattle out longer, according to research from the University of Liverpool.
Depending on control methods, farmers may not be protected for the later part of the grazing season.
Dr McCarthy says: “While preventative worm treatments have their place, farmers should be thinking ahead and vaccinating for long-term control.”
The risks around the likelihood of lungworm cases should be considered, ideally alongside a vet, says Dr McCarthy.
These could include buying-in stock with unknown disease history, being near a farm with a lungworm outbreak, and having lungworm on the farm in previous years and location. It is more likely in the ‘wetter west’.
She says: “Vets or suitably qualified persons can advise on farm-specific anthelmintic control plans and every time a farmer avoids using a wormer, it creates a good opportunity for cattle to create their own immunity.
“It is worth remembering that vaccinating against lungworm gives no protection against gut worms, which should be considered as a separate risk.”
IN THE FIELD: CHRIS McDONALD, NEWCASTLE-UPON-TYNE
TRANSITIONING from a conventional to organic dairy system meant a closer look at lungworm management for Bays Leap Farm manager Chris McDonald, Newcastle-upon-Tyne.
The 800-head herd has shifted from an all-year-round housing system to one that requires 150 grazing days per year.
Explaining his reason for the switch, Mr McDonald says: “We were relying on the milk price on our conventional system and when we put the numbers to paper, we realised the market was there for us to be better off financially long-term by going organic.
“Because the fields had not had cattle on them in years, we were unsure whether lungworm would be an issue when cows were introduced back into grazing, but it became apparent there was enough of a burden to cause notable issues for the herd.”
After noticing low yielding cows starting to cough towards the end of the grazing season in late September and October, Mr McDonald sought advice from his vet Jo Bates, of Farm Veterinary Services, who confirmed this was caused by a lungworm infection, sometimes referred to as ‘husk’.
As the farm was still transitioning from conventional at the time, cows were able to be treated with a nil milk withhold pour-on wormer.
But to stay in compliance with organic regulations and avoid future milk withdrawal periods, a lungworm prevention programme for the following grazing season was put together in conjunction with his vet.
Mrs Bates says: “As worming treatments were not a viable long-term option for the farm, we decided to focus on preventing future lungworm infections by vaccinating the entire milking herd prior to spring grazing.”
She explains the lungworm vaccine works via irradiated lungworm larvae which work their way to an animal’s lungs the same way lungworms would if ingested through grazing.
She says: “Because of this, vaccinated cattle can develop the signature cough temporarily when vaccinated, as larvae move towards the lungs, but since the larvae are irradiated, they cannot fully develop, allowing the animal to kill them off and develop enough immunity to get through the year.”
Mr McDonald’s whole herd was vaccinated to develop initial immunity, which will be maintained once cattle are turned to grass and exposed to larvae. In subsequent years, only youngstock will need to be treated.