LUNGWORM (Dictyocaulus viviparous) is most likely to be seen from June onwards in Wales with a peak in September/October.

Lungworm follows the same lifecycle on the pasture as other roundworms but once inside the animal there are major differences to the larvae’s development. This lifecycle can take as little as 10 days, stressing the importance of prevention as large numbers can build up in a very short period of time.

Lungworm larvae on the pasture can be spread by a fungus found in the dung pats, which explodes to spread its own spores and the lungworm larvae along with it. Development of larvae occurs particularly during warm wet weather in the summer and early autumn period and often coincides with the protective period of the longer acting wormers applied in the spring wearing off.

Clinical signs

Signs of lungworm in younger cattle (and dry dairy cows) include an increased respiratory rate at rest, but more noticeable, frequent coughing especially after short periods of exercise. Severely affected cattle may be reluctant to move, stand with their head down, neck extended, and cough frequently.

Disease can severely affect growth rates so much so that some farms it can take as much as 22 weeks more to finish the affected cattle. The cost in loss of production can far outweigh that from mortality.

In the milking herd, a reduction in the milk is noted along with frequent coughing when cows are walking to and from the milking parlour. With very large larval numbers on pasture, disease can occur in adult cattle even if they were vaccinated as calves and deaths can occur as a result. Milk production losses could reach £1.50 to £3 per head per day plus there is the treatment cost on top.

Diagnosis

Apart from the clinical signs the diagnosis of lungworm infestation is based upon the demonstration of lungworm larvae in the faeces. Antibody testing of blood can give an idea of previous exposure to lungworm (although timing of exposure is hard to pinpoint) and bulk milk testing can give an idea of herd level exposure.

Prevention

Prevention of lungworm is based upon development of immunity and is best achieved by vaccination (Huskvac) supported by strategic worming. Most available wormers will kill lungworm but cattle must be exposed to lungworm (and other parasites) during the grazing season to allow immunity to develop.

Some wormers can interfere with the vaccine, which involves dosing with live but inactivated lungworm larvae. Poor exposure during their first grazing season at pasture and failure to develop immunity renders cattle susceptible to lungworm during their second season at pasture especially if weaned beef calves graze the same fields every year (for example rented ground away from the main farm etc).

Speak to your Vet or SQP for advice about which products are best to use.