The tool can help monitor problems such as pneumonia, which can set a calf back on her growth as she battles the disease and lungs heal.
Ever have a non-ag person ask you why a dairy cow is so skinny? My answer is that she is not skinny; she has the body of an Olympic athlete. Then I ask the person to think about the body of a long- distance runner. That is the body of a dairy cow. We require our cows to perform like Olympic athletes.
To perform this well, we need the cow to be in her top condition and this begins when she is a calf. The rate-limiting organ in a calf the first year of life is her lung. This means that if she doesn’t have full use of her lung volume, such as what happens with pneumonia, then she will not grow or perform as well compared to her herd mates with healthy lungs.
Compared to a horse, an adult resting dairy cow has 30 percent of the physical lung volume but uses 250 percent more oxygen. Just ruminating and making milk requires a great deal of energy, and a cow will maximize lung capacity even though she is not running in a race. A cow does not have any reserve lung capacity to spare. If we want her to perform at her peak, then we need to ensure that she has the best feed and water, the necessary rest and the lung volume capacity to do the job.
This is where calf lung ultrasound has become a great tool for veterinarians and producers. With an ultrasound, you are able to visualize the lungs and any damage from pneumonia in real time, on-farm and in a live animal. With the same probe that is used for transrectal pregnancy diagnosis and fetal sexing, the lungs can be visualized.
Diseased lung from current or previous pneumonia can be easily distinguished from healthy lung. The ultrasound eliminates guesswork for veterinarians and producers when they need an accurate snapshot of what the state of respiratory disease is on their farm.
Questions that can potentially be answered are:
• How well is my calf doctor diagnosing pneumonia?
• How well are treatments working?
• How well is my transition program working?
• How well are my vaccines and prevention programs working?
The ultrasound can be applied to an individual animal or a group animal setting. On an individual animal, we want to know if more should be invested in treatment for the animal or if she is suited to stay in the herd. On a group basis, animals can be scanned after a period of stress or transition to monitor respiratory health based on objective ultrasound images, as opposed to treatment records that can be subjective or entirely missing.
For the busy veterinarian, lung ultrasound allows him or her to gain knowledge of the respiratory state of an operation in one visit. With ultrasound, the veterinarian can monitor the prevalence and incidence of calf pneumonia on an operation to make a final diagnosis. Both sides of the thorax are scanned, and the lung, from in front of the heart back to the diaphragm, can be visualized. Free fluid or effusion, fibrin and abscesses also can be seen with the ultrasound. After some practice, an entire exam can be performed in two minutes per calf.
Remember that adult cows are top-notch athletes and we expect them to perform at peak levels for at least 10 months of the year. We expect the same thing in our calves, as we want them to grow, come into puberty and never get sick.
Calfhood pneumonia can set a calf back on her growth as she battles the disease and lungs heal. Worst-case scenario is that the lungs never heal completely and she is later a fresh heifer with pneumonia that never makes it into the milking string. With the added tool of lung ultrasound, veterinarians and producers can work together to determine where the challenges are in an operation and monitor improvements and minimize procedural drift.
By Dr. Liz Adams, Technical Service Veterinarian, Merck Animal Health
Dr. Liz Adams is a graduate of the University of California, Davis, School of Veterinary Medicine. Dr. Adams is known for her work in using ultrasound technology to assess lung damage that heifers may have experience from early bouts of pneumonia, as well as evaluate bovine pregnancies and fetal sexing. She also specializes in the use of microbiology diagnostics to evaluate milk quality. Learn more at www.merck-animal-health.com.
