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Written by Administrator-GL
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Thursday, 17 July 2008 |
LUNGWORM
Dictyocaulus filaria (Large sheep lungworm)
Dictyocaulus viviparus (Large cattle lungworm)
Muellarius capillaris (Small lungworm)
Protostrongylus rufescens (Small lungworm)
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Large lungworm live in the airways
Small lungworm live in the lung tissue.
(Adult Large lungworms can be up to 3 inches long)
Large lungworm can actually block the air passageway, and at times coughing may produce adult worms.
Small lungworm will in time be encased in a nodule in the lung.
Small lungworm typically shows no sign of disease.
Adult worms live in the lungs and are coughed up and swallowed..
allowing for a secondary placement of egg infestation (the intestines).
Hatching of eggs take place in air passages or the digestive tract.
The larvae are expelled in the feces and in a moist enviroment they develop to infective stage in 3 to 7 days .
Adult worm lungworm in bronchi
adult lumgworm in bronchial passage
(click to enlarge image)
Showing mouth
Dictyocaulus filaria (Large sheep lungworm)
Larvae often curved
Sluggish movement
Size Length 550-585 mm
The larvae go through 4 stages of development.
Stage 1: Emerge in feces
Stage 2: First molt but do not shed skin-remaining enclosed.
Stage 3: Four (4) days after passing from animal , again retaining their sheath. Infectious larvae can live up to 9 months in water where they will be ingested by the animals drinking the water OR are eaten off grasses in pasture immediately. This Stage 3 larvae (L3) exsheath in the small intestine and penetrate the bowel wall where the will molt into Stage 4 larvae. (L4)
Stage 4: They larvae molt in lymph nodes and migrate to the lungs & heart via the thoracic duct.
They are approximately 1/50 inch long and are apparent in the bronchi in about 8 days after infection.
From the time of ingestion to the time they are in the lungs is approximately 2 weeks.
They molt into adults about 18 days after infection.
Produce eggs 3 to 5 weeks after infection.
Adult worms are excpelled through coughing at about 50 days after infection.
Most are gone at the 70 day mark after infection.
Although some may winter over in the lungs of the infected animal and some larvae may live by migrating deep in the soil mat, leaving the pasture infected for spring rise.
Large lungworm eggs are eaten off the grasses, the small lungworm larvae must be ingested by a snail to continue the cycle.
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Symptoms of Large Lungworm Infection:
- In heavy infections: During the first 25 days of infection there may be tachypnea and coughing.
During days 25 to 55 the lung signs increase in intensity with harsh lung sounds (bronchi and emphysematous crackling) being heard
- Rapid shallow breathing which in later stages becomes laboured breathing
- Possible elevated temperature- If there is secondary infection.
- Possible Nasal Discharge
- Emaciation
- Anemia
- Pneumonia or upper respiratory disease.
- (Severe infestations can cause suffocation)
- Grunting while at rest.
- Cyanosis, Recumbency and death can occur.
Post Mortem Findings:
- Haemorrhagic inflammation of bronchi with froth
- Consolidation of lung parenchyma
- Lung edema and emphysema
- Lung worms
- Enlarged lung lymph nodes Greyish-green nodules encysted or clacified with Muellerius capillaris infestation
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Last Updated ( Thursday, 17 July 2008 )
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