The effect of experimental Trypanosoma vivax infection on the thyroid gland in Zebu bulls

Thyroid gland dysfunction was studied in Zebu cattle experimentally infected with Dyponosoma vivax, based on the levels of serum thyroxine (T(4)) and Occurrence of pathological lesions at 13 weeks post infection (p.i.). There were statistically significant declines in the T(4) levels in the infected group at 3 weeks p.i. (P<0.05), 6 weeks p.i. (P<0.01) and front 9 to 11 weeks p.i. (P<0.05) when compared to the normal T(4) levels that were observed in the uninfected, control bulls throughout the period of study. The thyroid glands of both infected and control bulls showed no gross lesions and the mean weights were not statistically significant (P>0.05) between the groups. Histopathological lesions observed in the thyroid glands of the infected bulls were Focal in occurrence and include; squamous metaplasia of follicular epithelium with fibroplasia and widened interfollicular connective tissue. The control bulls showed no histopathological lesions in the thyroid glands. It was concluded that thyroid gland dysfunction occurs in trypanosomosis due to T vivax in cattle and it is suggested that this could contribute to the weakness associated with trypanosomosis..