HISTOPATHOLOGICAL STUDIES ON SO-CALLED KUWAZU DISEASE (COBALT DEFICIENCY) IN CATTLE IN JAPAN : I. FINDING OF MAIN ORGANS AND TISSUES

Abstract

The results obtained from these experiments indicate clearly the beneficial effect of a cobalt supplement to a cobalt-deficient basal ration and no beneficial effects of skim-milk powder, copper sulfate, and polytamin. Animals fed a cobalt-deficient ration manifested at first such symptoms as loss of appetite and body weight approximately 17 to 37 weeks after the start of the experiment. Affected animals revealed symptoms very similar to those observed in the case of cobalt deficiency. Such watery or serous discharge from the eyes as reported by REID, BEESON, and STEWART, however, was never encountered. It was difficult to find any specific clinico-anatomical findings of this disease. The most specific effect of cobalt drench upon cattle (E 1 and E 2) was the recovery of appetite. These animals revealed a dramatic cobalt response. After cobalt administration. appetite increased in three to five days. Rumination and peristalsis became regular. The cattle recovered their normal appearance in less than two months, but it took about four. months for pica and anemia to disappear. This dramatic response was demonstrated not only to administration of cobalt compounds but also intramuscular injection with vitamin B₁₂. Postmortem and microscopical finings of both natural (N 1) and experimental (E 3 and E 4) cases administered with non-cobalt compounds revealed no fundamental differences. They included marked atrophy of all the organs and tissues examined and lack of body fat. The cut surface of the spleen of cattle E 3 and E 4 fixed in formalin solution was brown in color, but that of the spleen of animal E 2 which had been administered with cobalt chloride per os daily for 291 days was dark gray. No inflammatory changes were noticed on the peritoneal surfaces of the abdominal organs. Histopathologically, marked hemosiderosis of the spleen and fatty degeneration of the liver were also reported in "nakuruitis" in Kenya and similar diseases in other countries. In all the materials examined by the authors, no hemosiderosis of the liver and kidneys could be demonstrated. The red cell count was always low in all the animals examined. The anemia of this disease would appear to be of microcytic nature, and anisocytosis and poikilocytosis were constant features. The same results were reported by FILMER and MARSTON. No macrocytic anemia was observed. This finding was not in agreement with that of IWAMOTO, who stressed that "kuwazu" disease might be a form of macrocytic anemia. SAHASHI and IWAMOTO, IWAMOTO, and SAHASHI stated that "kuwazu" disease seemed to occur from the deficiency of vitamin B₁₂ which Actinomycetes organisms produced. Their opinion was in accord with that of BECHER. Regarding hemosiderosis of the organs, there is a divergence of opinions among authors. MARSTON reported that hemosiderosis of the spleen was found to be much less pronunced than that of the liver and pancreas, and that pigment deposits were rarely observed in the kidneys. On the contrary, FILMER stated that hemosiderosis of the spleen was more conspicuous than that of the liver and kidneys. KITANO did not refer to hemosiderosis of the spleen in a goat affected with "kuwazu" disease. Such divergence of opinions concerning hemosiderosis may be due to the fact that different lesions developed in the different stages of the disease or to the difference in species of animals. Further endocrinological and histological studies are necessary to clarify the mechanism of apraxia of pigment granules in the mucous membrane of the proventriculi. The additional interesting findings observed are as follows. 1) Marked proliferation of germinal epithelial cells and fibrocytes in the lamina propria of the proventriculi. 2) Marked fatty degeneration of the adrenal cortex. [the rest omitted]