Brisket disease Cattle producers test for altitude issuesWritten by Sara Gugelmeyer
Ranching in the mountains isn’t all pretty views and deep meadow grass. High altitude definitely presents challenges. This important management factor is the reason why many high elevation cattlemen are using Hereford genetics.
Tim Holt, consultant, veterinarian and associate professor in the College of Veterinary Medicine at Colorado State University, is the widely acclaimed expert on grazing cattle in high altitudes.
After decades of research and testing, he says, while there is some variation within the Hereford breed, “the American horned Hereford tends to be naturally more resistant to altitude problems. Through the years, ranchers at high altitude that were having brisket disease issues have found some relief in the death loss by adding Hereford into their breeding program.”
To flatlanders, brisket is mostly just a really good cut of meat. But to producers at about 5,000 feet and higher, it’s a commonly-used term for a serious problem.
Brisket disease, also called high mountain disease, dropsy or more accurately pulmonary hypertension, occurs when the oxygen shortage at higher elevation causes increased resistance to blood flow in the small arteries of the lungs. The heart must compensate by building up a higher pressure.
Depending on the severity, the increased pressure results in right heart failure, which is seen as fluid buildup in the brisket, chest cavity and elsewhere. Ultimately, the heart fails and stops beating.
Cattle differ in how they respond to the oxygen shortage. Some can tolerate high elevation for long periods of time with no effects at all. That type of cattle is absolutely necessary to graze high-mountain pastures.
Tyler Knott of Knott Land and Livestock, along with his dad, runs 200 pairs near Oak Creek, Colo. Knott’s family has been in business in that area since 1936. Brisket has been at the forefront of nearly every management decision.
“The number one problem is death when we are dealing with brisket disease,” Knott explains in layman’s terms. “The cow cannot adjust her respiratory rate to compensate for the lack of oxygen at higher altitude, so her heart has to work harder to get the same amount of oxygen to the body. As the heart works harder, it increases blood pressure.”
Knott continues, “Then it becomes chronic disease. They start retaining fluids, and their performance is reduced. A lot of times on cows, we start having open cows because they can’t meet their reproductive nutrition demand when they are utilizing so much energy just to stay alive.”
“The acute side is their arteries will rupture or the heart will blow out,” he adds. “Ultimately, death is the end result of all brisket-related issues.”
Because of the risk and detriment of brisket disease, Knott notes that cattlemen in high altitudes have kept Hereford part of their herds.
Knott says, “Our cowherd has been historically Hereford-Angus based. For a while we went predominately black, and now our cowherd is about 70 percent Angus and mostly black-hided. We’ve been going back with Hereford bulls. We like the phenotype and performance of the Herefords. We can buy better Hereford bulls with less risk of altitude problems than we can Angus bulls.”
For high altitude producers, PAP testing is a must. PAP, or pulmonary arterial pressure, testing is the only way to determine a bovine’s susceptibility to brisket disease.
Since 1980, Holt has been traveling to high altitude operations and testing beef cattle. He estimates he’s tested more than 350,000 head to date.
The lower the score, the better, but there are many factors to consider. The test must be performed in high elevation.
Holt says, “Testing below 5,500 feet should always be viewed as a screening test, meaning that a high PAP score is accurate but a low score only means that at this elevation the animal may be a worthy candidate for altitude use but should be retested after arrival in higher elevations.”
“A high PAP score, regardless of elevation, is accurate,” he emphasizes, “but a low score at a low elevation should always be repeated once a higher elevation is reached.”
Other criteria involved include the age and sex of the animal.
One of only about 12 people in the country who performs the test, Holt gives the cattlemen the PAP score, as well as the systolic over diastolic blood pressure of cattle.
“Using those three numbers, it will help producers decide about each animal,” Holt says. “It’s an instantaneous evaluation, but we talk about each animal when it comes through and make a decision. We are making some big decisions right at the chute.”
Typically cattle with a score in the 30s or the low 40s will be fine at high elevations.
Holt cautions, “While the test is about 95 percent accurate when done at higher elevation, it is not the whole answer. A low PAP test does not mean the animal will never get brisket since there are other factors that can initiate the onset of the disease.”
“The PAP test can only tell if an animal has pulmonary hypertension,” he explains. “It cannot determine why. In most cases we think that the elevated pressure may be genetic in origin but we cannot forget all the environmental conditions that can result in brisket disease. Other influences that can be an issue are pneumonia, feed, and parasites, among others. There can also be congenital heart and lung defects.”
Though there are no guarantees, Holt estimates that about 90 percent of high altitude breeders utilize PAP score in some way.
PAP testing isn’t cheap, either.
Holt’s costs are about $22 to $25 per animal.
Each test also takes about three minutes, so there is considerable labor involved.
Without it though, the effects of brisket disease can be devastating.
“For a completely non-tested herd at 8,000 feet, the death losses that I see range anywhere from five to 10 percent of the calf crop with losses sometimes reaching 20 percent or more,” Holt says. “Cattle may exhibit other effects of altitude besides death including poor weight gain efficiency and compromised reproductive status.”
PAP or pulmonary arterial pressure is measured by a procedure called “right heart catheterization.”
Tim Holt, DVM and associate professor in the College of Veterinary Medicine at Colorado State University, has been performing this test since 1980.
To test the pressure, a small plastic tube is passed through a needle into the jugular vein with blood flow to the upper right side of the heart or atrium through a valve, then into the lower right side, or ventricle, through another valve and into the pulmonary artery just before it branches into the lungs.
Pressure waves are observed on a heart monitor and the monitor provides a readout of the average pressure.
The PAP score, combined with diastolic over systolic blood pressure, is used to determine if the animal is likely to be susceptible to brisket disease. The test is about 95 percent effective when done when the animal is acclimated, or has spent at least four weeks at 6,000 feet elevation or higher.
If the animal scores 45 or above, it is considered a moderate risk for high elevation use. An animal measuring above 48 is considered to be a high risk for elevation use. A “good” score, or lower risk measurement, would be 44 or below.
This is part one of a two-part article. In the next installation, producers discuss genetics that function well at high altitudes.