The wet weather conditions experienced in most parts of the country for most of the year mean that the lungworm burden is potentially quite high in stock.
Lungworm infection, or hoose, is one of the most significant respiratory diseases of cattle in northern Europe.
It is caused by the lungworm Dictyocaulus viviparus, which is a roundworm (nematode) parasite similar to gutworms.
As the name suggests, it completes its life cycle in the lungs rather than in the gastrointestinal tract.
According to Animal Health Ireland (AHI), the clinical signs of infection in cattle include coughing and difficulty breathing, especially when animals are being moved.
The recent weather has aided lungworm, and although many will have dosed stock at some stage already this year the chance of reinfection is high.
Warm, wet weather is the perfect condition for lungworms, which is exactly the weather we have had for most of the summer and autumn.
Some of the signs of lungworm are as follows:
- Mildly affected animals will have an intermittent cough, especially after exercise;
- Moderately affected animals will cough frequently while resting and have an increased respiratory rate;
- Severely affected animals will have difficulty breathing and may adopt a mouth-breathing stance with the head and neck out stretched, mouth open and tongue protruding;
- Lung damage can be severe and some of the pathology is irreversible, so deterioration of clinical cases and mortality can occur despite successful removal of the worms with an anthelmintic;
- Adult cows may also have a severe drop in milk yield. This can be observed before coughing is seen;
- Affected cattle have an increased susceptibility to other respiratory pathogens such as viruses and bacteria.
Close monitoring for early clinical signs of respiratory disease, particularly coughing, is the best approach for detection of lungworm infection.
Hoose is frequently suspected on clinical grounds alone, but other respiratory diseases must also be ruled out.
It may be confirmed by submitting dung samples for identification of lungworm larvae, but deaths from acute hoose can occur even before larvae begin to appear in dung samples.