Assessing Fetal Health: When is the Gestating Cria at Risk?

David E Anderson, D.V.M., MS, Diplomate ACVS
College of Veterinary Medicine
The Ohio State University, Columbus, Ohio

Assessment of fetal well-being is an area of on-going research at The Ohio State University. We have been concerned by the limited ability to determine if a gestating cria is OK. Any veterinarian who has tried to determine fetal viability by rectal palpation or determine the fetal heart rate using an ultrasound machine can tell you that it is not always easy.

The principle means for determining if a gestating fetus is OK is to observe the dam. If the dam is behaving normally, eating normally, and no changes in routine have been observed, then most likely the cria is fine. If more objective knowledge is needed because the cria is overdue, the female is being sold, or for other reasons, rectal palpation, vaginal examination, transabdominal ultrasonography, per rectum ultrasonography, and fetal ECG recording may be attempted. Rectal palpation is often difficult in Alpacas because of their small size, even when the hand can be fit into the rectum. If fetal movement is felt and the uterus has normal tone, we can say that the fetus is alive and all seems well, but is the fetus OK? Vaginal examination will allow assessment of the cervix. If the cervix is closed and no discharge is noted, then we can say that all appears well, but is the fetus OK? Ultrasonography is useful to examine the intrauterine environment and fetus. This is the mainstay of our current state-of-the-art evaluations. If the fetal thorax and heart can be seen, the fetal heart rate can be counted. However, we have seen fetal ultrasounds where there was no apparent heart beat, but the fetus was alive and was normal at birth. Although I am willing to say that a fetus is alive if I see a heart beating, I will not say that a fetus is dead or non-viable based on an ultrasound exam. Fetal ECG's are seldom successful because of the size of the abdomen, position of the fetus, and the overwhelming ECG of the dam. Therefore, what can we do?

Recently, we have been investigating the use of fetal Doppler ultrasound for assessment of fetal well-being. This technology provides us not only with fetal heart rate, but also fetal heart rate variability.