Ph Ysiologic Changes during Pregnancy

19 Anesthesia for the Pregnant Cat and Dog INTRODUCTION Anesthesia of pregnant animals, especially for Cesarian section presents a challenge for the veterinarian because the choice of therapy needs to assure a good outcome for both the fetus and mother. A basic requirement of all anesthetic drugs is their ability to cross the blood brain barrier. This capacity comes with the ability to cross the placenta, and therefore all anesthetic drugs will reach the fetus (though not all at similar concentrations). Pregnancy also results in physiologic changes in the dam, due to hormonal and physical changes e.g. increase in body mass and blood volume, which also influence anesthesia. Therefore when choosing sedatives, analgesics and anesthetics, the veterinarian should take into consideration issues such as physiological changes during pregnancy, teratogenicity of the drugs, perfusion and oxygen delivery to the fetus and cardiorespiratory depression in the neonate. This is complicated by the fact that cases that require anesthesia during pregnancy often present as an emergency, and therefore require prompt decision making. In this review we will discuss briefly the physiological changes during pregnancy, the anesthetic approach to pregnant and Cesarian section patients and finally, neonatal resuscitation.