Ultrasound aspects of fetal and extrafetal structures in pregnant cats

Prenatal feline fetal growth and utero-placental development were ultrasonographically evaluated using an ultrasound scanner with a 10 MHz sector probe. Uterus, placenta, embryo, fetus and fetal membranes in 16 pregnant cats were monitored during the course of pregnancy; 13 subjects underwent an ovariectomy on specific days while three subjects went to term. Various anatomic structures, fixed in Carson-buffered formalin, were sectioned and then compared to ultrasound images. By ultrasound examination it is possible to evaluate every stage of the fetal development; the gestational chamber can be seen on the 10th and the embryo inside the chamber on the 14th day. By the 20th day it is possible to evaluate all the fetal membranes, and later it is possible to appreciate organs and structures such as the stomach, intestine, eyes (crystalline lens), kidneys and the cerebral choroid plexi, on the 30th, 40th, 50th, 39th and 40th day respectively. Based on our observations, it will be simpler to locate anomalies of development or pathologies during ultrasound examination of pregnant queens.