These veterinarians developed a probe for determining pregnancy that is not only accurate but saves the wear and tear on the arm
While preg checking has traditionally be done by arm-in rectal palpation, technology is making it possible to use trans-rectal ultrasound probes to do the job with just as much or more accuracy and it’s a lot easier on the technician as well.
Andrew Bronson came to Alberta after graduating from Ontario Veterinary College in 1982. “Most ranchers have their cows pregnancy-checked in the fall,” says Bronson, who is based in Lethbridge, Alta. “I was proud of my palpating skills, because this is what makes or breaks you, as a beef cattle veterinarian.”
By age 45, however, the wear and tear on his arm and shoulder — multiple strain injuries after palpating cows all day — was taking a toll. He bought an aluminum extension-arm ultrasound unit, called a mechanical sector scanner. After using it several years, he saw the benefits of extension-arm ultrasound. Due to mechanical problems, however (and the long distance and turnaround time on repairs), Bronson and a partner, Bruce Hill, developed their own extension-arm ultrasound, called ReproScan.
Easy to use
This type of ultrasound equipment is much easier to learn to use than palpating, as well as being easier on the body. Also, there are certain stages of gestation in which ultrasound is much more accurate in determining the age of the fetus. “Then as the cow gets farther along in pregnancy, ultrasound is not quite as accurate as palpation for someone who’s done hundreds of thousands of palpations,” says Bronson. “But ultrasound is probably more accurate for the inexperienced person because it’s easier.”
While Bronson’s ReproScan was first used as a linear probe, he later changed to an ReproScan extension-arm unit working with a 4.0 MHz convex rectal probe. “This produces a pie-shaped image,” he says. “Depending on how it’s set, it can be as large as the size of your hand — versus a credit-card size picture with the linear probe (which is what most arm-in ultrasound units provide).”
Bronson says this is like the difference between hunting birds with a rifle instead of a shotgun. “It’s easier to hit a small target with a shotgun.” Bronson and Hill bought the convex probe technology from a company and designed their ReproScan probe as a portable unit.
“When we started out we thought the biggest market, initially, would be feedlot heifers,” says Bronson. “My partner and I were involved with live cattle exports when the border closed because of BSE. When it did reopen in 2005 all heifers had to be preg-checked because no pregnant cattle were allowed to be exported. So we did 150,000 heifers by ultrasound in 2-1/2 years. We would not have been able to do this number without extension-arm ultrasound.”
Veterinarians who spend a lot of time palpating or doing arm-in ultrasound find it physically demanding, and ultimately wear out. And with more women in the industry, the average height of veterinarians is dropping which makes it even more difficult for them to palpate cows all day. “Today the pressure is on veterinarians to go through a lot of cows quickly,” says Bronson. “Fewer veterinarians are interested in taking the time to learn to palpate.”
Ultrasound can do a good job of aging the fetus. “Under 120 days, ultrasound in general can be quite accurate — more accurate than anybody palpating cows, and there are some really good palpaters,” Bronson says. All forms of checking (palpation or ultrasound) become less accurate on fetal aging in advanced pregnancy. It becomes more difficult after 120 days’ gestation because the uterus drops below the rim of the pelvis and there are also variations in the size of the fetus and cotyledons.
“Other things start affecting the size of the fetus as well, including genetics and nutrition,” says Bronson.
There are many stories about sale-barn preg-checking errors.
“Even vets who have done hundreds of thousands of cows err now and then,” Bronson says. “Sometimes they have to put those cows into a one- or two-month window. If a cow comes in at what they think is a six-month pregnancy and it’s an eight-month fetus — and she calves earlier than expected and the calf freezes to the ground — the buyer is angry. But it’s easy to make that mistake, especially on a big old cow where you can’t reach the uterus.
“If you put our extension arm in there, however, and see large cotyledons and maybe a hoof, you can say it’s at least six months. When palpating, if you are good at this, you can get a feel for the weight of the uterus, size of uterine arteries, and all these things can give you information. Once you have done 100,000 or so, you can quickly say you think she’s more than six months — maybe seven or eight,” he says.
“My argument is that it’s not worth it. This is too hard on your body and you are still going to be off, now and then, by one or two months. This can be misleading to the person trying to put together a package of April calvers,” Bronson says.
Most of the old vets who were really good at palpating are gone or retiring. “Palpation is a difficult skill to learn and it’s hard for young veterinarians to gain experience quickly enough. It’s easier to learn to do ultrasound,” he explains.
The ReproScan equipment costs about $10,000, which is feasible for a veterinary practice, a big feedlot, or large cattle operation. “We now have a portable unit for veterinarians who want to save their arm. We have two groups who like our technology — the older vets who want things easier on their bodies, and the young vets who like the new technology,” he says. Bronson’s company provides demo equipment and training courses for veterinarians and producers. “Here in Western Canada we’ve been running mostly full-day classes on a regular basis.”
For more information on ReproScan email [email protected], or call 1-877-890-2411, or visit www.repro-scan.com. †