Lungworm disease in cattle is caused by the Dictyocaulus viviparus parasite, and is normally seen in mid to late summer, although infections can start as early as July. Boehringer Ingelheim Animal Health is urging cattle producers to lessen the risk of disease outbreaks by proactively managing pasture larvae levels throughout the grazing season and using an appropriate disease control programme.
Cattle may gain some immunity to lungworm either through vaccination before turnout, or through low level exposure at grass. However, this immunity can be short lived and if natural boosting does not occur during the grazing season, animals may be susceptible to disease when larvae populations on the pasture rapidly increase.
Pasture management
Heavy worm burdens can establish quickly on the pasture. A low dose challenge with around 200 larvae can lead to around 70 adult worms, which can result in 2.5 million infective larvae returning to the pasture by 30 days after ingestion(1).
Furthermore, studies have shown that up to 10% of cattle may be sub-clinical carriers of lungworm which means that without appropriate worm treatment, they will contribute low numbers of larvae to the pasture and increase overall pasture contamination(2).
Warm, wet summers provide optimal conditions for rapid increases in lungworm larvae populations on the pasture. In hot, dry weather, populations of infective larvae that have migrated from dung to grass can die through lack of moisture. However, larvae that have not yet left the dung pats will remain there until rain prompts the growth of the Pilobolus fungus on the dung. The fungus plays an important role in helping to disperse lungworm larvae, propelling them on their own spores up to three metres away and onto the pasture.
Costs considerations
Lungworm infections can result in significant losses of up to £137 per animal (1), comprised of lost income from reduced milk yield, reduced fertility and increased susceptibility to other diseases. Veterinary treatments can also be costly. Some severe cases of lungworm may be fatal, further increasing the disease cost from the disposal of dead animals and the cost of replacements.
Post-treatment, the impact of lungworm disease will be felt for the remainder of the animal’s productive life. The damage to the animal’s lungs caused by the parasites can leave them susceptible to secondary infections and affect their long-term productivity.
How to spot the signs of lungworm
Diagnosing lungworm at an early stage of infection can be difficult, and may not be spotted until a full-blown outbreak occurs.
“Lungworm should always be considered as a potential cause of coughing in cattle at grass,” says Mrs Bowden.
“However, the initial signs of coughing can be confused with other respiratory diseases such as Infectious Bovine Rhinotracheitis (IBR), particularly in older cattle, so it’s important that it is investigated early, to minimise the long term impact, rather than waiting until the whole herd is affected.”
Affected animals will have a deep harsh cough during activity which progresses to coughing at rest, with laboured breathing. Severely affected cattle will typically stand with neck and head extended in the ‘air hunger’ position.
Prevention and treatment of lungworm in cattle
Vaccination is an effective method for the prevention of clinical disease. However, this immunity may wane as the season progresses, and under high parasite challenges, cattle may still be at risk of late-summer outbreaks.
An alternative approach is a strategic worming programme throughout the grazing period. Products such as Ivomec® Classic (ivermectin) and Eprinex® (eprinomectin), which are used to treat intestinal parasites including gutworm (Ostertagia ostertagi), will also treat lungworm. For this approach to be effective, producers must remain alert for signs of disease. Additional treatments may be required later in the grazing season.
If lungworm is diagnosed, the whole herd should be treated as soon as possible with a suitable anthelmintic with prolonged activity against reinfection, to allow the lungs time to recover. Eprinex has a zero milk withhold and prevents reinfection with lungworm for up to 28 days after use.
It’s vital that all animals in the herd are treated as some infected individuals will not show obvious clinical signs but will still suffer from impaired performance.
For more information, speak to your animal health medicines advisor or your vet.
References:
Vercruysse J, Janssens PG, Vercruysse J, Jansen J (1989) Ductyocaulosis. Worms and Worm Diseases Samson Stafleu, Alphen aan den Rijn/Brussel, pp 210-222. Eysker M, Classens EW, Lam TGM, Moons MJ, Pijpers A (1994) The prevalence of patent lungworm infection in herds of dairy cows in the Netherlands. Veterinary Parasitology 53 (3-4) 263-267. Eprinex Pour On for Beef and Dairy Cattle contains eprinomectin. Ivomec Classic Injection and Ivomec Classic Pour On contain ivermectin. POM-VPS. Further information is available in the SPCs or from Boehringer Ingelheim Animal Health UK Ltd, RG12 8YS, UK. UK Tel: 01344 746960 (sales) or 01344 746957 (technical). Eprinex and Ivomec are registered trademarks of the Boehringer Ingelheim Group. ©2019 Boehringer Ingelheim Animal Health UK Ltd. All rights reserved. Date of preparation: Jun 2019. AHD 12097.Use Medicines Responsibly.
