Accurate pregnancy detection in beef cattle is an important way to direct management decisions such as culling.
Rectal palpation and ultrasound are used in most situations.
New blood tests are being developed for pregnancy detection in cattle, but they remain expensive and face a delay between sample collection and the results.
A major advantage of rectal palpation for pregnancy detection is that it is fast and the results are immediately available.
Rapid, accurate pregnancy detection with minimal risk is ideal, no matter what technique is used.
Heard Systems from Australia is developing a handheld device to detect pregnancy in cattle.
It is placed on the skin of the cow’s flank and uses sensors to detect fetal heart sounds and electrical signals. This data is then analyzed using computer software to filter out the background noise.
The technology is touted as being non-invasive, user friendly and less stressful, but it is still in the development stages.
Of course, when products such as this one become commercially available, they will open the floor for debate on which procedures are considered to fall under the scope of practicing veterinary medicine.
A major drawback of rectal palpation for pregnancy detection is the physical risk to veterinarians and livestock handlers.
The technique requires specialized skills, physical stamina, practice and appropriate handling facilities.
In fact, an Australian study found that 37 percent of major injuries sustained by cattle veterinarians occurred during pregnancy detection or other obstetrical procedures.
Rectal palpation is commonly used in early pregnancy to detect the amniotic sac, which is the fluid that bathes the fetus in the uterus. Palpation of the amniotic sac must be done carefully to avoid rupturing the sac or directly damaging the embryo, which are both possible with inexperienced practitioners or repeated palpations.
Previous studies have found in-creased risk of atresia coli in fetuses that were palpated.
This is a fatal congenital anomaly in which the colon fails to form properly.
There have been conflicting results on how rectal palpation for pregnancy detection affects fetal loss.
In a University of Minnesota study, dairy cows were inseminated and checked for pregnancy 29 days later using ultrasound. Cows were then randomly assigned to one of two groups.
The control group of cows was not rectally palpated for pregnancy detection, while a single veterinarian palpated the other group between 34 and 43 days of gestation. All cows were then given ultrasounds at days 45, 60 and 90 to determine if there was pregnancy loss.
Researchers found that there was no difference in pregnancy loss between the cows that were palpated and those that were not.
They concluded that a single rectal palpation by an experienced veterinarian did not result in pregnancy loss.
A real strength of this study was the use of a control group, which was not palpated during the same time period.
The bottom line is that cows and heifers that are palpated in the fall but fail to deliver calves come spring might be losing their fetuses for other reasons: genetic abnormalities, environmental factors such as nutritional deficiencies or toxins, and infectious causes such as bovine viral diarrhea. Given the surge of interest in alternative techniques, pregnancy detection by palpation may quickly become a thing of the past.
Dr. Jamie Rothenburger is a veterinary pathology resident at the Western College of Veterinary Medicine, University of Saskatchewan.