[Clinical signs in late pregnant mares]

During the peripartal period, interpretation of basic clinical signs may be challenging. In the present study, heart rate (HR), respiratory rate (RR) and body temperature (BT) were evaluated in healthy mares of different breed types and compared to reference values for adult horses from the literature.

During daily physical exams of periparturient mares, the HR, RR and BT were evaluated. Differences according to the horse's size were investigated and in large breeds, the influence of dystocia or retained placenta was analysed.

During the last weeks before parturition (a. p.), the HR significantly increased and was clearly lower after parturition (p. p.; p < 0.05). In larger horses, the RR increased a. p. and decreased p. p. (p < 0.05). The BT underwent changes in all groups during the periparturient period and was higher p. p. (p < 0.05). In general, values for HR, RR and BT were highest in ponies (p < 0.05) while the lowest RR was measured in large horses (p < 0.05). There was no difference in the HR between mares with eutocia or with dystocia (p > 0.05). By contrast, the RR was significantly higher in mares with dystocia on day 1 p. p. (p < 0.05). Differences in the BT a. p. and p. p. occurred only in mares with eutocia (p < 0.05) and remained within the normal values. Mares with retained placenta did not exhibit significant changes in the HR (p > 0.05), but the BT was higher on day 1 p. p. (p < 0.05).

Increased HR, RR and BT in mares during late pregnancy suggest a distinct physical performance for a prolonged period of time. Interpretation of these parameters in relation to the mare's reproductive state is essential to diagnose potential disorders and to determine whether therapy is required.