Nervousness and hysteria of mature female chickens

A type of abnormal nervousness and hysteria, e.g., adding nests and perches to community cages and and hysteria affecting White Leghorn female chickens 35 or more weeks of age was investigated in nine experiments. Experimental flocks in which the malady consistently occurred were housed in large group (community) cages. Limited information was obtained on three cases in commercial flocks housed on the floor. Social pressure resulting from high population density appeared to be primary causative factor, with pain apparently contributing to the final break to hysteria. Claw removal at one day of age prevented hysteria but not nervousness in one experiment. Colored light, feeding added niacin or a mild tranquilizer were not successful preventives. Short term feeding of a high level of niacin, claw trimming and forced molting afforded relief in some cases while a heavy sedative was ineffective as a curative. Modification of the environment to reduce social pressure was successful in preventing nervousness and hysteria, e.g., adding nests and perches to community cages and moving flocks to less crowded housing. Strain differences in tendency to develop hysteria were demonstrated. There were positive indications of physiological changes associated with hysteria.