Checking cattle for pregnancy: Rectal palpation versus ultrasound

Beef 911: Both methods have advantages, but the key 
is having reproductive exams at least once a year

Both rectal palpation and ultrasounding for pregnancy have advantages depending on their intended application, and both require a skilled veterinarian performing the pregnancy exam to get accurate results.

I will outline the pros and cons of each method so you can see how to best fit them into your farming operation, and dispel some myths and fallacies surrounding pregnancy examination. In this dry year, pregnancy checking the herd earlier is a way to remove culls and ship open cows in order to both preserve grass and sell when the market for cows is typically highest.

Related Articles

cow and newborn calf

Rectal examination has been performed by veterinarians for eons and very 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 estimates.

There are several reasons for this. First, 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 minutes of each other, it is not uncommon to have the recipients calving up to one month apart. Depending on breed and sex of calf, gestations also vary greatly. The veterinarian may palpate the non-pregnant horn of the uterus giving a false underestimation of pregnancy status. The most important things are whether the cow is open or is late.

With a good setup with a skilled veterinarian, up to 100 head can be checked in an hour. I still frequently hear that pregnancy examinations can cause abortions, but there is only a very slight risk in the real early stages of pregnancy (around 30 days) and skilled palpators are seldom in the rectum for more than a few seconds, which minimizes any risk. Nor, as some believe, do we manipulate the fetus during the examination. Rough handling and banging through the chute are more likely to cause abortions than any rectal palpations ever have — but with today’s setups that is very rare indeed.

One must keep in mind abortions still normally occur in two to three per cent of cattle yearly. This has numerous causes, including genetic defects, infectious causes, twinning and trauma.

A good setup preferably has a palpation cage, OB sleeves and lube. Veterinarians always need to find a positive sign of pregnancy. This involves balloting the uterus or feeling for the presence of cotyledons. In confirming a cow open, the whole reproductive tract is explored. The only cows that are difficult to do are extremely fat ones. Their internal fat pushes the uterus down making it difficult to reach and retract to confirm an open uterus.

Ultrasounding requires a large capital outlay for the veterinarian and the diagnostic intent may be different.

Reproductive problems can be explored since you can differentiate fluid from pus and make a more definitive diagnosis. If interested in fetal sexing this (although more difficult and time consuming) can be accomplished when cows are 55 to 75 days pregnant. The ultrasound is very accurate in the 30- to 75-day range, but less so in the later stages of pregnancy.

Newer ultrasounds have probes that get much deeper so allow more accuracy later in pregnancy. Others have introducers whereby the veterinarian’s arm does not even enter the rectum. We need to watch these as occasionally the rectum can be perforated and a massive peritonitis is the result. Vets use lots of lube if using the probe introducer.

Fine feel and gentleness are virtues when it comes to rectal palpation. In inexperienced hands, full bladders may be misdiagnosed as pregnancies and other pregnancies can be missed. Veterinarians have gladly embraced this ultrasound concept since rectal palpation is really hard on shoulders and elbows. You will find most mixed practices use ultrasounds and the newer-graduate veterinarians are well trained in their usage. In any pregnancy examination we must strive to be 99 per cent-plus accurate in the pregnant versus non-pregnant department. Opens are diagnosed with the ultrasound and often double-checked by palpation by the attending veterinarian just to be sure.

With a good internal probe (quality of ultrasounds also varies considerably) besides fetal sexing, twins can be picked up and this may help the producer manage these cases differently. The fetal sexing is impossible doing manually and twins will rarely be picked up. Again though, cows must be ultrasounded early in pregnancy for this to be accomplished. Very early embryonic deaths can be diagnosed where you have a fetus but no fetal heartbeat indicating a dead fetus. Cysts on the ovaries can also be detected and easily differentiated between luteal and follicular. These cysts require a slightly different treatment regime, which your veterinarians can explain.

As you can see, both forms of pregnancy examination have merit. Rectal palpation being fast and safe is commonly done in most beef herds and is an important management tool. Ultrasounds generally are also used in problem breeders or when specialized procedures such as fetal sexing are required. Cows being sold with sexed embryos are often reconfirmed in calf by rectal palpation later in the year. Pregnancy checking, whether manual or with ultrasound, is done by upwards of 70 to 80 per cent-plus of cattlemen across Western Canada, but it should be much higher when we think of the feed costs this saves or being able to identify problem breeders earlier. It is even more critical as far as purebred cattle are concerned with more dollars tied up in that unborn calf.

If there has been a reproductive disease go through the herd, it can be caught earlier and dealt with. Much better to find you have open cows at weaning than at calving time when you finally notice cows aren’t bagging up. At the same time as pregnancy examination, reproductive problems can be explored and cows can be condition scored; vaccinations given; lice and worming treatments implemented or discussed with your veterinarian.

Lots can be done at the pregnancy examination visit to help with the year-round health of your herd so let’s utilize this opportunity to the fullest for both the purebred and commercial herds.

There are advantages to both techniques, but at the end of the day the most important thing is to have reproductive exams performed on your beef cattle at least once a year. If handling setups are available at pastures, pregnancy checking can be done early to remove opens.

Keep in mind other management procedures can be done in the summer at the same time such as vaccinating, deworming and fly control.

About the author

Contributor

Roy Lewis practised large-animal veterinary medicine for more than 30 years and now works part time as a technical services veterinarian for Merck Animal Health.

Comments

explore

Stories from our other publications