The effect of gastrointestinal parasitism on blood copper and hemoglobin levels in sheep.

Endoparasitism is a problem in Trinidad, as it is in most tropical countries. Parasite infection has been suspected to contribute to the pathogenesis of swayback disease (which is also prevalent in Trinidad), but the mode of action has not been clearly defined, although it has been suggested that parasites interfere with the absorption of copper from the gastrointestinal tract. The objectives of the study were to assess the effect of endoparasitism on blood copper levels and hemoglobin (Hb) concentration in sheep in Trinidad. Copper was administered intramuscularly to parasite infected and noninfected animals. The results showed that parasitism has a depressing effect on blood copper and Hb levels, even when administered parenterally. It is concluded that parasitism can aggravate existing hypocupremia and possibly influence the expression of swayback disease.