Page 42

Working Ranch April/May 2016

for PAP testing, many veterinarians and high elevation ranchers feel strongly about the importance of the test. The goal of PAP testing is to identify bulls that may be at risk of developing Brisket Disease before they have a chance to pass the condition down to progeny. Brisket Disease, which also goes by the names High Mountain Disease and Dropsy, causes the heart, specifi cally the right ventricle, of animals at high elevations to fail. As oxygen becomes less available at higher elevations the heart is forced to work harder to provide blood to the body. In some animals this extra effort causes the muscles of the heart to wear down and blood fl ow to back up. In some cases the increased pressure can cause the valves to blow out. Outwards, the animal will appear to have swelling in the neck or brisket area and occasionally in the jaw. However, often times the disease progresses so quickly that these symptoms are not noticed until the animal is found dead and examined by the owner. Traditionally, Brisket Disease was only considered a risk for animals living at high elevations of 6,000 ft. or higher; however, the last decade has seen a surprising increase of incidence in feedlot animals at elevations as low as 3,000 ft. Many experts believe that this is due to the high rate of gain achieved by the effi cient feeders, which puts extra strain on the heart. One such expert is Dr. Tim Holt, DVM, who is often considered the foremost expert on Brisket Disease and the ultimate authority on PAP testing. “Cattle have changed a lot in the last few decades, growing so much faster. Genetics may be outgrowing cardiac capacity,” suggests Holt. The process of PAP testing is not an easy one, and not all veterinarians are trained to do it. According to Holt, in order for the test readings to be accurate, cattle must be tested at a minimum elevation of 6,500 ft. The test, which measures the amount of force required to push the blood from the heart to the lungs, produces a raw number score. A score of less than 41 is considered acceptable for most ranchers. To obtain this score a small hole is made in the neck of the animal. A catheter is then inserted into the jugular vein and threaded into the right ventricle of the heart and the main pulmonary artery, between the heart and lungs. Holt says the process is fairly painless for the bull and they really feel “just a needle stick.” Because of the elevation needed for testing Holt does not foresee a time in which every bull is tested, despite the growing number of Brisket Disease cases. He does, however, see a future where genetic testing also plays a role in the fi ght against Brisket Disease. Holt says there are studies underway to fi nd a genetic marker for the disease. While the ability to determine which animals are genetically prone to the disease would help eliminate genetic cases it would not eradicate cases with environmental causes. Because this DNA testing, once developed, would not identify all potentially impacted animals, Holt believes that PAP testing will continue to be vital for all ranchers whose animals will spend time in high elevations. According to Holt, Brisket Disease at high elevations can cause a death loss of 15-20% of a calf crop. The last decade in the livestock industry has been witness to unparalleled technological advances with even greater achievements on the horizon. As the industry moves forward there is potential for improved testing and detection for high impact diseases such as trich and Brisket Disease. Coupled with the possibility of more unifi ed trich testing regulations, the future of herd health and disease prevention looks encouraging with fewer calves lost, a benefi t to ranchers and consumers alike. Traditionally, PAP was only considered a risk for critters ranging in elevations of 6,000 ft. or higher; however, the last decade has seen an increase of the problem in feedlot animals at elevations as low as 3,000 ft. 42 I WORKING RANCH I APRIL / MAY 2016


Working Ranch April/May 2016
To see the actual publication please follow the link above