Abstract. Changes in plasma T4 levels were investigated in prepubertal and adult female goats during the course of an experimental Trypanosoma congolense infection. A significant decline in the T4 levels was observed within 1 week of trypanosome challenge. The levels remained low up to the end of the 7th weeks when prepubertal goats received a trypanocidal treatment, whereafter the values started to rise to normal pre-infection values. The post-infection plasma T4 values in the untreated adult goats did not return to normal except in one resistant goat which recovered naturally after 16 weeks of the infection. The thyroid glands of chronically infected and untreated adult goats revealed marked atrophy, fibrosis and colloidopathy. It is concluded that trypanosomiasis rapidly impairs thyroid gland function in susceptible animals, but these changes can be reversed by early trypanocidal treatment before marked degenerative changes become evident or following self cure in resistant animals.
B. M. Mutayoba, H. B. O'hara-Ireri and S. Gombe
B. M. Mutayoba, S. Gombe, E. N. Waindi and G. P. Kaaya
Abstract. Adult normocyclic female goats experimentally infected with Trypanosoma congolense developed irregular and shorter estrous cycles before complete cessation at the fourth cycle post-infection. This was followed within a month by a decline in the mean plasma progesterone and estradiol-17β levels. The peak luteal progesterone as well as pre-ovulatory estradiol-17β level declined progressively from the second to the fourth cycle post-infection. The ovaries became atretic with reduced numbers of primordial and primary follicles. The larger follicles became atretic at the tertiary stage with subsequent lack of corpora lutea formation. The rapidity of ovarian dysfunction appeared to be related to the degree of susceptibility of the individual infected goats.