集约化生产中的动物会因长期慢性应激而导致心理疾病或精神异常，是福利水平下降的标志。以往检测家畜心理状况的方法都是间接的，鉴于人类瞳孔反射异常与抑郁症等心理疾病相关的临床有效性启示，有必要开展哺乳类家畜瞳孔反射的基础研究，探索直接检测其心理状态的有效方法。前期研究发现限位饲养母猪存在瞳孔光反射延迟现象，且该现象与异常行为和神经递质、激素水平存在一定联系。如能证实其内在的必然联系，就可以开发一种通过瞳孔检测来评价母猪福利的新方法，为畜禽个体福利状态的临床检测提供新途径，但前提是要明晰母猪瞳孔光反射的基本生理特征。本研究结合母猪品种、年龄、心理适应性、生理与免疫水平、饲养环境等因素，开展母猪瞳孔光反射生理特征的研究，旨在了解遗传、生理、环境对猪瞳孔光反射的影响及修饰，系统的探索母猪瞳孔光反射特征及其影响因素，为确定瞳孔反射能否作为检验动物心理异常或慢性应激提供理论依据及可行的基础技术参数。

Animals suffering chronic stress should give rise to psychological and mental problems which leads to decline in animal welfare. Existed methods detecting psychological condition of domestic animals are usually indirect, thus it is necessary to explore possible direct method measuring welfare condition. In referring to human's cases that abnormal pupillary light reflex is related to depression. Previous studies showed that sows in farrowing crates performed attenuated PLR characteristic, and also found that its attenuated PLR characteristic was related to psychological stress and physiological condition. If we can can prove the inherent relations. It would be allowed us to establish a new way to evaluate animal welfare, and provide a new way for clinical detection of welfare for domestic animal individual. The purpose of the study is to consider the sows' breed, age, psychological adaptation, physiological and immunological condition and housing environment as the possible influence factors and observe their effects on characteristics of sows' PLR; this can help us theoretically understand the functions of heredity, physiology, environmental conditions on sows' PLR and its modification, and also help us explore the sows' PLR characteristics and the factors leading to psychological problems. It could provide a theoretical basis and technical parameters for establishing a new non-invasive method of detecting chronic psychological stress to evaluate the welfare of sows.