Lungworm infestation (commonly known as “hoose” or “husk”) can cause severe respiratory issues in cattle of all ages and can often be fatal.
The lifecycle of the lungworm is about 4 weeks long – from the ingestion of larvae to the excretion of infective larvae onto pasture in faeces. Within four weeks of ingesting lungworm larvae, a cow or calf could be shedding millions of larvae onto the pasture. In one case, a faecal output of 1,850,000 larvae per day was recorded.
An outbreak of lungworm in a herd can have a significant economic impact, due to severe losses in milk yield, poor fertility, treatment costs and culling/death.
The rise in lungworm cases in the last number of years has been linked with over-use of wormers in our herds. The use of long-acting wormers in cattle may prevent the development of natural immunity to lungworm.
Clinical Signs of Lungworm
The clinical signs of lungworm infestation include coughing and increased respiratory rate (breathing faster). Coughing may initially be evident only when animals are disturbed but progresses quickly to frequent coughing, even in resting animals. Animals harbouring lungworm are more prone to viral or bacterial pneumonias. Death can occur if left untreated.
Diagnosis can be made based on clinical signs and farm history. Lungworm larvae may be found in the faeces of infected cattle, but this method of detection is not always reliable. Multiple faecal samples and often broncho-alveolar lavage (a lung washing technique used by vets to capture lungworm larvae) may be needed to confirm the presence of lungworm in the airways.
With varying climates and cattle densities in Ireland, some counties are more prone to lungworm infestation than others. Warm and humid conditions favour larval survival on pasture. As a result, outbreaks peak in late summer and early autumn. Rain can further amplify lungworm issues, as larvae can be spread across pasture by rain. A fungus called Pilobolus found on dung pats also aids in dispersing larvae.
Pasture management is a key factor in preventing lungworm outbreaks. Lungworm outbreaks occur when naïve (previously unexposed) grazing animals are exposed to high levels of lungworm larvae on pasture.
Grazing dairy replacements on separate pasture, away from the main herd, has become a popular practice. Dairy replacements often graze the same pasture as replacement groups of previous years. This pasture may be relatively free of lungworm larvae and these animals are often subject to continuous worming, When the replacement animals finally enter the main herd and encounter lungworm larvae in the faeces of older stock on pasture for the first time, an outbreak is highly likely.
This situation contrasts strongly with beef suckler herds, where calves are commonly exposed to a continuous low level of challenge from being grazed with older animals. Continuous exposure to low levels of lungworm over time aids in immunity development.
Combining vaccination, worming and appropriate pasture management is the most effective way to control lungworm in cattle.
Bovilis Huskvac is the only vaccine for the active immunisation of cattle to reduce the clinical signs and lesions associated with lungworm. It can be used with strategic anthelmintic dosing and appropriate pasture management to control lungworm.
It is an oral vaccine for use in calves 8 weeks of age or older. Two doses, given 4 weeks apart, are required as a primary course. The course should be completed 2 weeks prior to turnout.
For optimum benefit, it is important that the calf is exposed to pasture carrying some lungworm larvae after this time, as this low level exposure enhances the immunity induced by vaccination with Bovilis Huskvac.
Oral lungworm vaccine
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