Dairy veterinarians are constantly looking for ways to make a better or faster diagnosis to solve their clients’ problems or monitor the health of herds. In the last few years several interesting tools are being used by dairy veterinarians to do just that, including tapping into the human side. Here’s how some dairy veterinarians are using those tools.
BHBA meter for ketosis
Human patients with Type I diabetes mellitus are at risk for diabetic ketoacidosis and often need to monitor their blood β-hydroxybutyrate (BHBA). Monitoring blood BHBA in human patients is superior to monitoring urine acetoacetate using urine test strips. Abbott Laboratories has developed a very small hand-held meter (Precision Xtra) that measures either whole blood BHBA or whole blood glucose. “As far as we know, no other human glucometer can also function as a ketometer (i.e., able to measure blood BHBA),” says Garrett Oetzel, DVM, MS, University of Wisconsin. “The Precision Xtra meter gives excellent results for measuring whole blood BHBA in cows. No additional calibration or adjustment from the human system is needed.”
Oetzel was first contacted about the meter three years ago by Abbott Animal Health. “I had been evaluating the literature about ketosis testing and was aware that the currently available tests were not ideal,” he says. “I was excited about the possibilities for using a cowside test that was both rapid and accurate. I’ve also been concerned that ketosis appears to be more prevalent than it used to be in the dairy industry.”
Oetzel adds that this the best tool we have for identifying ketosis in dairy cattle. “It is almost as good as sending a sample to a laboratory, which would be impractical because it takes at least a day to get the results back.” The other cowside tests (milk, urine) are not nearly as accurate as the ketone meter, he says.
Oetzel recommends the ketone meter for both herd-based screening for ketosis (to evaluate transition cow management) and for testing individual sick cows (to decide whether the cow should be treated for ketosis or not). To assess ketosis on a herd basis, the protocol involves testing 12 or more cows in early lactation. If more than 10 percent of the cows tested have blood BHBA ≥ 14.4 mg/dL (1.4 mmol/L), then the group is considered to have a ketosis problem.
Mark Thomas, DVM, Dipl. ABVP, Countryside Veterinary Clinic, LLP, Lowville, N.Y., also uses the BHBA strips as a tool for herd-based testing when he suspects a possible issue with ketosis. “I generally select 12 healthy fresh cows from 5–20 days in milk for sampling,” he says (see sampling practice tip on page 24). Thomas likes to sample cows about 4–5 hours after feeding.
“If there are more than 10 percent (two or three out of 12 cows) above the cutoff of 1.4 mmol/L, then I am concerned about a herd problem of ketosis,” Thomas notes. “It has been shown that these cows are at a greater risk for displaced abomasum, and increased BHBA negatively affects future reproductive performance. It is useful to have results quickly available so that we can have a discussion about potential changes to address the ketosis as opposed to waiting days to a week for results from the lab.”
Oetzel adds that some researchers and clinicians use a lower threshold for ketosis of 1.2 mmol/L, then increase the acceptable number of cows above this threshold from 10 percent to 20 percent.
Thomas says the meter can also be used to test individual suspect ketotic cows where it is difficult to obtain urine. “I have also used the meter to allow herdspersons to become more comfortable in not treating every cow that changes the urine dipstick positive for ketosis,” Thomas says. “The meter can be used in conjunction with the urine test strip to show the level of blood BHBA. Given the cow’s attitude, appetite and milk production level, we can re-train the treatment crew to be more selective in cases to treat.”
How it works
The Precision Xtra ketone monitoring system is a simple and direct electrochemical test (which may explain why it works well for both human and bovine blood). The ketone test strip contains the enzyme β-hydroxybutyrate dehydrogenase, which oxidizes BHBA to acetoacetate. This reduces NAD+ to NADH. The NADH is then reoxidized to NAD+ by an electron transfer mediator molecule. The electrical current generated by this conversion is measured by the meter and is directly proportional to the BHBA concentration.
For cowside use, Oetzel uses a small syringe (1 to 3 ml) and small needle (20 or 22 gauge, 1-inch long) to collect a small amount of blood from the tail vein. Because the amount needed is very small, it is easy to train someone to be able to collect blood this way. Thomas says he doesn’t even use a syringe to get the sample and instead pricks the tail vein with a 20x1 inch needle to get the drop of blood. ”It’s less waste of plastic, so it’s a ‘greener’ procedure,” Thomas says.
After collecting the blood you can insert the ketone test strip in the meter, then apply a small drop to the end of the test strip. The meter displays the blood BHBA concentration in 10 seconds. “We are using it exactly as labeled for humans,” Oetzel says.
Oetzel says the Abbott Precision Xtra meter is available from most veterinary distributors for about $50, and the blood ketone test strips (which measure BHBA) are about $40 for a box of 10 strips, or $4.00 per test. Thomas notes that you can shop around and that recently saw the meters for around $15 at Walmart. Oetzel cautions against buying cheap strips from eBay or other web vendors as they may be very short-dated or even out of date. “Out-of-date strips cannot be used — the meter will give an error message and will not display a correct ketone reading
Oetzel offers these suggestions for getting the most out of the meter:
During cold weather the meter and strips should be kept warm before using. Store them inside in a warm place, then put them in an inside pocket before heading out to the pens to do the ketone testing. Don’t leave the meter or the strips out in the cold.
Don’t let the strips get wet before use. They are individually wrapped in foil packets; just be careful to keep them dry after unwrapping them.
Thomas likes to use the Lactocorder as a tool for parlor performance reviews. The Lactocorder is an extremely accurate milk flow meter. The device can graphically show inadequate stimulation of milk letdown, poor timing of parlor procedures, overmilking and more. “It provides a visual assessment of the prep procedure,” Thomas says. “It is very useful in that we can make certain changes in prep lag time or procedure and observe the effects of these changes with the milkers. It is a useful accompaniment to milker training sessions where I can share the graphs from the dairy.” Thomas also uses the Lactocorder to evaluate automatic take-off settings.
One tool Greg Goodell, DVM, The Dairy Authority, Greeley, Colo., doesn’t like to be without for milk quality work is the somatic cell counter by DeLaval. The DCC herd management tool can measure and monitor the cow, quarter or bulk tank somatic cell count in under a minute, on the farm. “On individual cows it gives a quick and accurate count of SCC,” Goodell says. The meter is a small (about 12 inches x 16 inches x 12 inches) machine that uses cassettes to sample SCC of individual cows. Goodell says the cost is around $3,000. It works well in a mastitis lab but can run on batteries so is easily taken by veterinarians to different farms for different programs.
Goodell has been using the meter for about two years and says it’s holding up well, but should be calibrated annually. “We use it to take clients to the next level of milk quality,” he explains. “It’s probably not right for all clients, but it’s nice to have for those clients where a high level of milk quality is desired, such as those in special incentive programs, organic dairies, cheese programs, etc. If the veterinarian does any milk quality work, then he or she would likely find a use for this machine.”
Needle-free injection systems have been and are being developed for livestock use. Some of the players include Acushot Inc. and Pulse Needle-Free Systems. According to Pulse NeedleFree Systems, the advantages of needle-free injections include:
Biosecurity Animal health is improved by eliminating needles that transfer disease.
Enhanced efficacy Vaccine efficacy is improved by needle-free injection that exposes the vaccine to the dermal layer, rather than bypassing this important tissue with a needle.
Food safety Meat is safer because there is no potential for broken needle fragments in consumer products.
Productivity Carcass yield is increased because of less tissue damage.
Speed Labor costs are reduced in large-scale injection programs.
Worker safety Worker injuries from needle sticks and repetitive motion injuries are greatly reduced.
Environmentally friendly No medical waste disposal costs.
Dose accuracy Human error is reduced when the “automatic” injection process delivers the drug dose instantaneously into the tissue.
A.I. gun warmers
Goodell also favors the use of an artificial insemination gun warmer for reproductive work. “Instead of the breeding technician shoving the AI gun down his shirt to keep it warm as he walks to the cow, it is inserted into a gun warmer for a more consistent environment.” An Internet search reveals A.I. gun warmers that have 12-V adapters and battery chargers, temperature indicators and shoulder straps for easy carrying.
“It seems there is always something new coming out,” says Goodell. “The trick, however, is to get it validated. Many time a new gadget or special mix for ketosis is released without validation and of course this gives credence to the fly-by-night sort of outfits.”
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