Studies on trichostrongylosis of sheep plasma volume, haemoglobin concentration, and blood cell count

Abstract

The plasma volume of worm-free crossbred wether lambs was found to vary from 33 to 56 ml/kg during normal growth from 8 to 12 months of age. An inverse relationship was found to exist between plasma volume relative to body weight and body weight for lambs of this age. Infection of lambs with Trichostrongylus colubriformis, even when fatal, did not produce any alteration of plasma volume except that due to change in body weight. For all determinations made on all 26 sheep used, the mean plasma volumes were: 13–25 kg body weight, 46.83 ± 3.7 ml/kg; 26–30 kg body weight, 43.2 ± 3.2 ml/ kg; 31–38 kg body weight, 41.2 ± 3.8 ml/kg. The differences in plasma volume between the three body weight ranges were statistically significant (P < 0.001).

The clinical syndrome in these experimental cases of trichostrongylosis was characterized by unthriftiness with failure to grow normally, loss of weight, and emaciation. None of the sheep showed diarrhoea. All infected sheep developed a moderate to severe degree of anaemia due to decreased numbers of erythrocytes.

It is concluded that diarrhoea is an incidental clinical sign in trichostrongylosis, and is not essential for the disease to terminate fatally. The data presented suggest that water loss is not an important component of the syndrome.