Atlas of livestock parasites
digitized collection of microscopical preparations

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Toxocara (Neoascaris) vitulorum (cattle)



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Nematode (order Ascaridida)

"large roundworm"

Distribution: worldwide. 

Host: Small intestine of cattle and bison. These large roundworms are widely distributed, serious parasites of young cattle, especially in warm areas. 

Life Cycle: Cattle are infected following the ingestion of larvated eggs in the environment. Second-stage larvae of Toxocara are infective and develop within the eggs. This process takes about 17 days on pasture. These infective eggs are eaten by the host and hatch in the intestine. The larvae penetrate the intestinal wall and migrate to other tissues, such as the liver, lungs, and kidneys. In pregnant animals, Toxocara can cross the placenta, infecting calves before birth. This nematode can also pass in colostrum to newborn calves. These larvae reach reproductive maturity about 3 weeks after the calf is born. Self-cure occurs in 4 to 5 months. Adult worms are not usually found in mature cattle. 

Diagnostic: Large, creamy-white worm with blunt ends, up to 30 centimeters long and 5 mm in diameter. Detection of typical ascarid-type eggs with fotation procedures.              

Size: 75–95 × 60–75 µm Eggs are round and have small pits on their surfaces.

Clinical features: As part of the normal life cycle, larvae may travel through the lung and cause pneumonia in calves. Adults in the intestine compete with young hosts for food, causing diarrhea and weight loss. Coughing due to pneumonia may occur when larvae lodge in the lungs.

Pasture management; anthelmintic treatment of cattle, especially during pregnancy.                


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