Kaitlin Gisler
Dr. Lisa McCrea has been using ultrasounds during her on-farm herd health since she graduated from veterinary school. She brought the technology with her when she made the move to the West Coast in 2007 and became a partner of Agwest Veterinary Group, a large animal practice in the Fraser Valley. She is an expert in ultrasonography, and the technology has come a long way since she started.
“I began with a non-portable ultrasound strapped to a cart and wheeled behind me,” recalls Dr. McCrea via email, “to the backpack and monocular Easi-Scan that I have today.”
The veterinarian uses ultrasounds on all of her farms, whether she is palpating one cow or the entire herd.
“This enables us to set up more successful breeding programs for our clients.”
The main components to an ultrasound machine are the probe which sends out the ultrasound waves, and a viewing device that can be a stand-alone monitor, wrist display or goggles depicting the image picked up by the probe. The probe is used internally or externally, and contains crystals which create and receive the ultrasound waves. When a wave encounters tissue it is either reflected or refracted back to the probe, or absorbed, which affects the image shown on the monitor. Black objects represent fluid, meaning the waves passed through and did not bounce back; dense areas, such as bone, show up white since it strongly reflects the waves. Varying shades of grey help identify the difference between the body structures. Bovine ultrasound technology is very similar to the ultrasounds used with people and gives more insight than only fetus health and gender.
“Gender affirmation is just a small piece of why we use an ultrasound in our herd health. The ultrasound provides a more accurate and complete picture of what is going on reproductively…you are able to diagnose pregnancies more accurately [and] earlier…you are able to see the viability of the fetus which you cannot do with a rectal palpation…so early embryonic death can be dealt with quicker. Some of my clients like to know if they’re having twins so they can take extra care coming up to calving. Most important of all,” states Dr. McCrea, “the ultrasound gives a more accurate assessment of the ovarian and uterine abnormalities than a rectal palpation.”
BCF Technologies, a worldwide manufacturer and distributor of imaging equipment, lists the numerous benefits of using ultrasounds; from diagnosing if a cow is pregnant or open (non-pregnant) within twenty-seven days after breeding, and determining the gender by fifty-five days. Pregnancy checks can become ten per cent quicker with a skilled technician, putting less stress on the cattle. BCF Technologies estimates that with a herd of a thousand cows or fewer, when the extra cost per open cow is four dollars per day, an ultrasound can be paid back in two years.
For farmers wanting to learn this technology, there are DVDs and books available, as well as 2–3 day courses that provide hands-on training. Farmers who are practiced at breeding their own cows are usually able to learn how to scan the uterus to check for a pregnancy; but Dr. McCrea suggests a farmer’s time can be better spent focusing on other aspects of their operation, while a veterinarian can bring their skill and background knowledge of bovine reproduction to determine pregnancies and much more.
“That is only the tip of the iceberg,” explains McCrea. “I use ultrasound on hundreds of cows each day, looking for ovarian structures, uterine health and assessing the viability of the embryo. It has now become an invaluable extension to my palpating arm that I wouldn’t trade.”
