A rare case of diabetes found in a dairy heifer brought to the University of Calgary veterinary medicine school (UCVM), shouldn’t alarm dairy producers that this is wide-scale animal health risk, but it should underscore the importance of following a proper vaccination program, says a senior instructor.
The 19-month-old heifer, which later died and was tested extensively in a post-mortem, developed diabetes as a secondary infection to the Bovine Viral Diarrhea (BVD) virus, says Gordon Atkins, a long-time practising dairy veterinarian who is a senior instructor at UCVM.
“It was a very interesting case, which has some important messages for dairy producers,” says Atkins. “Cases of diabetes are so rare, that really that in itself is of no significance to most dairy farmers. However, it does emphasize the value of following a proper vaccination program on the farm. We also learned some valuable information about monitoring dairy herds for other metabolic disorders.”
The 19-month-old heifer was brought to UCVM after a referring veterinarian had diagnosed diabetes in the animal. Third-year vet med student Emily Ames received an award from the Western Canadian Association of Bovine Practitioners for the case study she conducted on the diabetic animal.
“In a literature review she found only three other cases of documented bovine diabetes and of those there was only one in Canada,” says Atkins. “Emily did an exceptional job in studying this case and made an outstanding presentation, representing UCVM extremely well.”
The diabetes itself is interesting because it is extremely rare, says Atkins, but the real message is the importance of a proper herd vaccination program.
BVD is a widespread and common virus, which affects not only dairy and beef cattle, but can be transmitted to other livestock species such as goats, sheep and bison.
There are effective vaccines, but to be effective, first treatments should begin in calves as early as two months of age. And Atkins emphasizes the importance of insuring all females are properly vaccinated before being bred.
An infected heifer or cow can transmit the BVD virus to the unborn fetus and the fetus, with an undeveloped immune system, will incorporate the disease as a seemingly normal part of its cell structure. The newborn calf becomes a life-long carrier and distributor of the BVD virus to the rest of the herd. Those carriers are known as persistently infected, or P.I., calves. Usually a P.I. calf is a “poor doer,” and most don’t live beyond two years. (See a related column on BVD in beef cattle in the February 7 issue ofGrainews,Page 23).
The animal with diabetes brought to the UCVM was a P.I. calf, but actually was quite a normal looking, healthy dairy heifer, that was in fact 60 days pregnant.
As noted earlier, rarely do animals that contract BVD develop diabetes. Tests showed the UCVM heifer had no pancreatic function whatsoever, although it was not clear whether that was caused by the BVD virus itself, or whether the animal’s autoimmune system shut down the pancreas in response to the virus. Regardless of the specific mechanism, Atkins says with the BVD virus present and no pancreatic function, diabetes developed.
The effect of BVD on cattle is variable. “We had another P.I. animal that we examined shortly after we received the one with diabetes, and the second animal had perfectly normal pancreas function even though it was a BVD carrier,” says Atkins.
As part of their research, UCVM veterinarians did treat the diabetic heifer with 100 units of porcine insulin and discovered that was effective, although very expensive. “It wouldn’t be an economically viable treatment in the average dairy animal, but in an exceptional case where you may have a very expensive cow and you want to treat her on a short-term basis for two or three months until she calved, it may be warranted,” says Atkins. “But otherwise it would be cost prohibitive.”
One other important finding while treating this heifer involved the effectiveness of a human blood glucose monitoring unit. As the affected heifer was treated for diabetes, veterinarians questioned whether there was an effective hand-held monitor that could be used to measure blood glucose. They tried the Abbott Precision Xtra blood glucose and ketone monitoring system, which was developed for human diabetics, and found it very effective in measuring blood glucose and ketone levels in the dairy heifer.
Atkins sees a real value in being able to use this monitor to quickly evaluate the nutritional status in dairy cattle. “The hand-held monitor can measure blood ketone levels,” he says. “So if you had a group of fresh cows, for example, and wanted to evaluate whether your nutritional program is adequate to take them through the transition period, you can take small blood samples from the group and in 10 seconds you have a digital read out of ketone levels.
“This is a tremendously valuable tool in monitoring ketone levels and the management of their dietary requirements and also the management practices that ensure they have adequate dry matter intake and adequate energy concentration in the ration so we minimize metabolic diseases.”
For an effective defense against the BVD virus, Atkins says vaccination programs should begin as early as two months of age, and by the time heifers reach breeding age they should have been vaccinated three times. “The juvenile vaccination program is necessary to establish a solid base of immunity in the animal,” he says. This basic vaccination program, should be followed by routine booster shots as the heifer/ cow matures.
Atkins says in a closed herd, where cattle are under a proper BVD vaccination program, the risk of BVD should be extremely low. The greatest risk to this herd comes from the introduction of any purchased animals where the vaccination protocol is not known.
LeeHartiseditorofCattleman’sCornerbased atCalgary.Contacthimat403-592-1964orby emailat [email protected]