CHRONIC SELENItM POISONING IN DOGS AND ITS PREVENTION BY 2

A number of papers have been published concerning the effect of chronic selenium poisoning on growth, food consumption, reproduction, and pathology of several species of laboratory animals (1, 2, 3). Little is known about the-effects of chronic selenosis on the blood constituents (except hemoglobin), par-tially because of the limited quantity of blood which can be taken from small laboratory animals such as the rat, rabbit, and cat. Therefore it seemed ad-visable to study the effects of chronic selenium poisoning on the blood picture of larger animals. Dogs were selected for this purpose as convenient sources of blood samples sufficiently large to be analyzed for most of the commonly de-termined constituents. Dogs are also large enough to furnish, at autopsy, samples of various organs and tissues large enough to be analyzed for selenium. The second part of this study was undertaken to determine the effect of ar-senic when fed to dogs receiving a ration which contained selenium. It had been found that arsenic would prevent or counteract the effects of selenium in rats (4, 5, 6). Later work has shown that arsenic has the same beneficial effects when fed to pigs receiving a seleniferous ration (7). Recently a report on the effect of acute selenium poisoning in dogs was made from this laboratory (8), but there are no reports in the literature describing-chronic selenosis of dogs. EXPERiMENTAL. Thirty-four dogs have been used in this work. Fourteen dogs were used in the first part of the study between September, 1935, and October, 1936, primarily to determine the effect of a seleniferous ration; and twenty were used in the second phase of the investigation to determine the effect of arsenic in addition to a seleniferous ration