12. Bovine Endoparasites

What is the life cycle of Ostertagia ostertagi?

It involves eggs hatching in feces, developing into L3 larvae, which are ingested by cattle, mature in the abomasum, and cause disease.

How is Ostertagia ostertagi transmitted?

Through ingestion of L3 larvae from contaminated pastures.

What are the clinical signs of Ostertagia ostertagi infection?

Weight loss, diarrhea, reduced appetite, and poor growth rates.

How is Ostertagia ostertagi diagnosed?

Fecal egg counts and clinical signs such as diarrhea and weight loss.

What treatments are available for Ostertagia ostertagi?

Anthelmintics such as ivermectin and fenbendazole.

What is hypobiosis in Ostertagia ostertagi?

It’s a period of arrested development of larvae within the host during unfavorable conditions.

Are heifers at higher risk for Ostertagia ostertagi?

Yes, especially during their first grazing season due to lack of immunity.

What is Type I ostertagiosis?

Disease occurring in young cattle during high pasture contamination periods.

What is Type II ostertagiosis?

Disease caused by reactivation of inhibited larvae in older cattle.

How can Ostertagia ostertagi be prevented?

By managing grazing patterns and using strategic anthelmintic treatments.

What environmental conditions favor Ostertagia ostertagi development?

Warm and moist conditions facilitate larval development on pasture.

What resources help predict Ostertagia ostertagi burdens?

Weather monitoring and pasture management strategies.

What is the life cycle of Dictyocaulus viviparus?

Eggs hatch in the lungs, larvae are coughed up, swallowed, and passed in feces; L3 larvae develop on pasture and infect cattle through ingestion.

How is Dictyocaulus viviparus transmitted?

Through ingestion of L3 larvae from contaminated pastures.

What are the clinical signs of Dictyocaulus viviparus infection?

Coughing, tachypnea, dyspnea, and potentially death in severe cases.

How is Dictyocaulus viviparus diagnosed?

Clinical signs and fecal examination using the Baermann technique to detect larvae.

What treatments are available for Dictyocaulus viviparus?

Anthelmintics like ivermectin are effective against lungworm.

Are heifers at higher risk for Dictyocaulus viviparus?

Yes, particularly during their first grazing season when they lack immunity.

How can Dictyocaulus viviparus be prevented?

Vaccination with Huskvac and strategic anthelmintic use.

What environmental conditions favor Dictyocaulus viviparus development?

High humidity and moderate temperatures promote larval survival on pasture.

What is the role of Pilobolus fungus in Dictyocaulus viviparus transmission?

It aids in dispersing larvae across pastures via spores.

How does Dictyocaulus viviparus cause disease in cattle?

Larvae migrate to the lungs causing bronchitis and pneumonia.

What resources help predict Dictyocaulus viviparus burdens?

Monitoring climatic conditions and using disease forecasting systems.

What is “re-infection husk”?

A condition where previously immune cattle are overwhelmed by large numbers of larvae on heavily infected pastures.

What is the life cycle of Fasciola hepatica?

Eggs hatch into miracidia that infect snails; cercariae emerge from snails, encyst as metacercariae on vegetation, which are ingested by cattle.

How is Fasciola hepatica transmitted?

Through ingestion of metacercariae on contaminated herbage or water plants.

What are the clinical signs of Fasciola hepatica infection?

Poor growth rates, reduced milk yield, liver damage, and anemia.

How is Fasciola hepatica diagnosed?

Fecal sedimentation tests and serological assays for antibodies.

What treatments are available for Fasciola hepatica?

Triclabendazole for early immature stages; albendazole for adult flukes.

Are heifers at higher risk for Fasciola hepatica?

Yes, especially if they graze in areas with high snail populations or wet pastures.

How can Fasciola hepatica be prevented?

By controlling snail populations and using strategic anthelmintic treatments.

What environmental conditions favor Fasciola hepatica development?

Wet environments support snail hosts necessary for parasite development.

What role do snails play in Fasciola hepatica’s life cycle?

They serve as intermediate hosts where asexual reproduction occurs before cercariae emerge.

What resources help predict Fasciola hepatica burdens?

Disease forecasting systems and environmental monitoring for snail habitats.

How does Fasciola hepatica cause disease in cattle?

Liver damage from migrating juveniles leads to fasciolosis with chronic symptoms.

Can Fasciola hepatica infect humans?

Yes, humans can become infected by ingesting contaminated water plants like watercress.

What are common parasites of grazing cattle?

Ostertagia ostertagi, Dictyocaulus viviparus, and Fasciola hepatica.

Outline the life cycle of Ostertagia ostertagi.

Eggs hatch in feces; larvae develop to L3 stage on pasture; cattle ingest L3; larvae mature in abomasum causing damage.

How does Dictyocaulus viviparus cause clinical disease?

Larvae migrate to lungs causing bronchitis and pneumonia, leading to coughing and breathing difficulties.

Describe clinical features of Fasciola hepatica infection.

Causes fasciolosis, leading to poor growth, reduced milk yield, and liver damage.

What are the principles of preventing Ostertagia ostertagi infections?

Use anthelmintics and manage grazing to reduce exposure to infective larvae.

How can parasite burdens be predicted?

By monitoring weather conditions and using pasture risk assessments.

What are clinical signs of lungworm infection in cattle?

Coughing, tachypnea, dyspnea, and severe cases may lead to death.

Are heifers at more risk of getting these parasites?

Yes, especially during their first grazing season due to lack of immunity.