Sudden death of calves by experimental infection with Strongyloides papillosus. III. Hematological, biochemical and histological examinations.

Nine calves infected percutaneously with graded doses of Strongyloides papillosus (SPL) were examined for hematological, biochemical and histological changes during the infection. Six of the calves infected with the highest larval doses died suddenly and the three calves given lower doses survived. No changes were observed in blood cell counts except for a transient eosinophilia. Parameters of the blood coagulation system and blood gas remained normal. A decrease in blood glucose was observed in four of the calves that died after the prepatent period of the parasite. However, endotoxic shock could be ruled out as a cause of death because of normal platelet counts, no intravascular coagulation and low levels of serum endotoxin. A transient increase of creatine kinase was observed in three of the calves that died; however, myocardial infarction or myocarditis were not observed. No lesions were observed except for minor inflammatory changes in the lungs and slight cellular infiltrations in the heart. In the absence of any consistent hematological, biochemical or histological changes in the calves that died, the present study failed to demonstrate mechanisms underlying sudden death due to SPL infection.