Abstract: This invention relates generally to animal crate construction such as farrowing crates for a sow and her new born piglets wherein a farrowing crate and a pair of associated side pens in which the piglets are free to move are provided. The farrowing crate includes vertical standards at each corner of the crate having a pair of interchangeable side members slideably received thereover spacing the vertical standards longitudinally and upper and lower bridger flanges carried between the tops and bottoms, respectively, of the standards so as to space the standards and opposed side members laterally. A pair of interchangeable door members are pivotably attached at each upper and lower bridger flange so that the door members can be selectively opened from each side. The interchangeable side members have offset side frame portions so as to vary the width of the crate interior when the side members are carried by the standards in a reverse or interchangeable manner.