Thermographic Pregnancy Diagnosis in Bears
Giant panda Bai Yun gave birth to Mei Sheng on August 19, 2003.
Pregnancy diagnosis in bears is confounded by long, variable periods of delayed implantation during which time preimplantation embryos or placental membranes cannot be visualized by ultrasound. Thermography is the generation and analysis of images created by measuring skin temperatures, which are reflective of underlying temperature variations. Thermography is a well-recognized diagnostic tool in human medicine and can be readily applied to exotic animals because of its non-invasiveness.
Serial thermographic imaging of the San Diego Zoo’s adult female giant pandas was performed by Dr. Barbara Durrant of the Reproductive Physiology Division of the San Diego Zoo's CRES following natural breeding in the spring of 2003. Uniform heat signatures over the reproductive tract were indicative of an overall perfusion of blood to both uterine horns by Day 48. This perfusion may represent the increase in blood flow to the uterus prior to implantation. By Day 97 two distinct heat signatures, one in each uterine horn, appeared to represent two growing placentas as their sizes greatly exceeded the estimated size of giant panda fetuses. On Day 134 ultrasound scans revealed two live fetuses in the exact location of the two heat signatures visualized simultaneously, thus confirming the veracity of thermal imaging to diagnose pregnancy in the giant panda.
On Day 150 a single live fetus survived to parturition. Thermographic analysis has the potential to detect pregnancy and fetal loss near the time of or shortly after implantation when ultrasound is not effective. It is of great interest to establish the actual frequency of multiple conceptions and to quantify peri- or post-implantation fetal loss in this species. Pinpointing the time of fetal loss will enhance knowledge of the physiology of gestation in the panda as well as providing the opportunity to intervene, thus increasing the potential for multiple live births.
