Lungworm - Clinical Signs and Lesions

Severe clinical signs and post mortal lesions are only seen with heavy lungworm infestation. The aim of lungworm control is to prevent clinical signs and subsequent economic losses.

Clinical signs

Clinical signs vary from occasional coughing to severe respiratory distress depending on the number of infected larvae ingested during a relatively short period. Clinical disease has an incubation period of around three weeks from ingestion, and can therefore occur a few days before larvae appear in the faeces. By the time clinical disease is present, the health of the cow or calf is already severely compromised because of the extensive damage that can be caused by worms in the lung tissues.

In adult dairy cattle, milk drop may be a typical clinical sign. By the third week, severely affected cattle stand in a characteristic head-extended position with rapid shallow breathing and frequent coughing.

Lesions caused by lungworm infestation

Lungwork infestation

Fluid accumulates in affected lungs which together with obstruction of bronchi by adult worms causes collapse of lung tissue or emphysema.
Eggs aspirated into alveoli can cause an inflammatory reaction in the lung parenchyma.
Secondary bacterial infections can lead to bronchopneumonia.