Rectal palpation and using ultrasound for pregnancy both have advantages, depending on their intended application.
To be accurate, both must be carried out by a skilled veterinarian.
Veterinarians have performed rectal examinations for a long time and little has changed in this science. It is a relatively quick, cost effective and safe procedure in the right hands.
Accuracy is good in the early stages of pregnancy (30 to 90 days). In mid-gestation (four to seven months), it is not uncommon for veterinarians to be out two weeks to a month in their estimate. Several things account for this.
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Gestational length still varies tremendously. I always use the example of a flush of embryos put into recipient cows. Even though genetics are identical and they are implanted within hours of each other, it is not uncommon to have the recipients calving up to a month apart.
A veterinarian may also palpate the non-gravid (pregnant) horn of the uterus, giving a false underestimation of pregnancy status. The most important thing is whether the cow is open or late.
With good setups and in a skilled veterinarian’s hands, rates of up to 100 head per hour can be accomplished.
I still frequently hear the myth that pregnancy examinations cause abortions. There is only a slight risk in the early stages of pregnancy (around 30 days) and skilled palpators are seldom in the rectum for more than a few seconds, which drastically minimizes risk.
Veterinarians do not manipulate the fetus. Rough handling and banging through the chute are more likely to cause abortions than rectal palpations, although that is still rare. Fetuses are well protected in the cow’s abdomen.
Abortions normally occur in two to three percent of cattle. There are numerous causes, including genetic defects, infectious causes, twinning and trauma.
Equipment to palpate should include a palpation cage, obstetric sleeves and lube.
Veterinarians need to find a sign of pregnancy, which involves feeling for the presence of cotyledons or the fetus. The entire reproductive tract is explored to confirm a cow is open.
Cows that are extremely fat are difficult and take extra time to test. Their internal fat pushes the uterus down, making it difficult to reach.
Ultrasound
Using ultrasound requires a large capital outlay for the veterinarian, and the diagnostic intent should be different than for palpation tests.
Reproductive problems can be explored because veterinarians can differentiate fluid from pus and make a more definitive diagnosis.
If producers are interested in fetal sexing, this can be accomplished when cows are 55 to 75 days pregnant, although it is more difficult and time consuming.
Ultrasound is accurate in the 30 to 75 day range and highly inaccurate in the later stages of pregnancy.
Even though external probes have recently been advertised, they are inaccurate because of the mass of tissue to penetrate.
Full bladders are misdiagnosed as pregnancies and other preg-nancies are easily missed with these machines.
Veterinarians would have welcomed these probes because rectal palpation is hard on shoulders and elbows. Unfortunately, they are too inaccurate for pregnancy checking large animals and too slow to be practical.
Pregnancy examinations are inadequate if accuracy of pregnant versus non-pregnant doesn’t reach 99 percent.
A good internal probe can determine fetal sexing and split twins, although the quality of ultrasounds also varies considerably. This is something rarely diagnosed with straight rectal palpation.
However, cows must be tested with ultrasound early in pregnancy for this to be accomplished.
Early embryonic deaths can be diagnosed, in which there is a fetus but no fetal heart beat.
Cysts on the ovaries can also be detected and differentiated between luteal and follicular. These cysts require a different treatment regime.
Veterinarians usually need to set up their ultrasound screens in a shaded area close to the chute.
The electronics, especially the probe ends, are subject to damage from rough handling and are expensive to fix.
New technology has developed ultrasound machines with goggles so setting up screens and monitors has become a thing of the past.
Both forms of pregnancy examination have merit.
Rectal palpation, being fast and safe, is commonly done in most herds. Without all the necessary equipment, it is also considerably less expensive.
Ultrasounds generally are used in problem breeders or when specialized procedures such as fetal sexing are required.
Cows sold with sexed embryos are often reconfirmed in calf by rectal palpation later in their gestation.
Up to 70 percent of western Canadian beef producers ask for rectal palpation for pregnancy. Open cows, even purebred ones, become a liability to feed over winter, especially this year with short and expensive feed supplies.
Reproductive problems can also be explored during a pregnancy check and cows can be condition scored. These are worthwhile procedures in a ranching operation.
