The immune system of the bird is often disturbed by the activity of various immuno-suppressors, both non infectious (linked to breeding conditions) and infectious. In group T1 and T4 the lymphocytes were densely packed in cortex as well as in medulla. The height of epithelium was more in group T1 followed by group T4, T2 and T3. Lymphoid follicles were well developed and showed greater interfollicular connective tissue in group T1. The diameter of follicle was more in group T1 followed by group T4. In group T3 the number of follicles per mm2 was more while diameter of follicle was the smallest among all groups. The muscle layer was composed of smooth muscle fibers. The amount of connective tissue in the serosa was more in the group T1. The splenic tissue showed major red pulp and smaller white pulp in all treatment groups. The white pulp was spherical in appearance in group T1 while it was irregular in shape in other treatment groups. The cells of the red and white pulp were densely populated in T1. The diameter of white pulp was greater in group T1 among the all groups.
Horse, Idiopathic tetanus, Treatment
