On-the-farm incidence and nature of equine dystocias

Abstract

The characteristics of parturition and dystocia were recorded on standardized forms by foaling attendants on 8 farms for 517 spontaneous parturitions. Dystocias were classified from examination of the forms into those with malposition (involving the fetal body), malposture (involving fetal extremities), and normal position and posture in which traction was considered essential. Dystocias occurred in 58 of 517 (11.2%) parturitions and involved normal fetal position and posture (31.0%), malposition of body (22.6%), and malposture of extremities (41.4%). Other recorded frequencies were for emergence of an intact chorioallantois at the labia (2.0%), hiplock (1.2%), posterior presentation (0%), uterine torsion (0%), deformed fetal limbs *8.4%), stillbirth (1.2%), death of foal within 24 hours (1.2%), life-threatening injury to the mare (1.5%), and retained placenta (13.5%). The frequencies of a prolonged or excessive Stage 1 culminates in rupture of chorioallantois, (11.5%), deformed foal limbs (24.0%), relatively large foal (26.8%), and retained placenta (22.0%) were greater (P<0.05) for mares with dystocia than for mares without dystocia (2.6, 6.7, 7.9 and 10.5%, respectively). Ten of 14 (72%) dystocias with normal position and posture were attributable to a relatively large foal or weak maternal contractions. All of 16 malpositions of the body involved a tendency toward the dorso-pubic position (upside-down) and 31% were accompanied by malpostures of the extremities. Observations suggested that alternate standing and lying by the mare played a role in preventing and aiding in the self-correction of malpositions. Most (55%) of 24 malpostures involved retention of a front foot. The primary indicators of a problem were the absence of any fetal parts or membranes at the labia for a prolonged time after rupture of the chorioallantois (28% of dystocias) or the emergence of only one foot (34%). The interval from foal delivery to placental discharge was shorter (P<0.01) for Miniature Horses (17±3 min; n=17) than for the larger breeds (54±2 min; n=395). In 3 of 19 (16%) miniatures, the placenta and foal were delivered simultaneously. It was judged necessary to rupture manually an intact amnion in 2 of 5 miniatures on one farm.