top of page
  • Hollow Top Angus

Importance of PAP Testing

Updated: Sep 21, 2023

This blog describes the importance of PAP and our protocol for PAP testing our herd. More information on the bulls is available on our website and will be available in our sale catalog to be released around October 20th for our upcoming Production Sale being held at Montana Livestock Auction in Ramsay, MT (online at Cattle USA and Northern Livestock) on November 19th.

High Altitude Mountain Disease (HMD) or “Brisket” disease is a disease of the bovine heart that ultimately can lead to death. Pulmonary Arterial Pressure Testing (PAP) is a test that is used to assess the likelihood that a bovine is susceptible to the disease if placed at high altitudes.

Early on, Hollow Top Angus (HTA) had cows that died from the disease, and from that point forward we have focused resources and our attention to provide PAP-tested bulls and heifers for our customers.

Why are we concerned about HMD? HMD is a disease that primarily impacts cattle raised above 5,000 ft of elevation or are transferred to high elevation from significantly lower elevations. Since HTA believes its primary market area is defined as SW Montana, northern and western portions of Wyoming, and Idaho, much of which is above 5500 feet in elevation, HMD is or should be a major concern of our customers.

AAA has developed an EPD (expected progeny difference) factor as an “indicator for animals with lower risk of developing high altitude disease” (

AAA claims that the PAP tests should be used “to select animals to avoid pulmonary hypertension”. In other words, they believe that the PAP EPD is an indicator of the likelihood that a given bull will be susceptible to the disease.

HTA places far less credence in the PAP EPD as it stands today and instead uses PAP tests to define the likelihood that a specific animal will be susceptible to the disease. A PAP test is a procedure whereby a catheter is passed through the jugular vein to the right ventricle of the heart, through a valve, and into the pulmonary artery. Once in the artery, average blood pressure is measured in millimeters of mercury (mmHg). There are a couple of conditions that must be present for the test to be relatively accurate: First, the animals should live at elevations over 5000 feet for at least 21 days before the test. Second, the age of the animals is important as well. PAP test accuracy improves as the bulls mature. Accordingly, tests on a 2-year-old bull are more reliable than tests taken on yearling bulls.

At HTA we closely monitor PAP. Our herd bulls with very few exceptions have either been tested and have good actual PAP readings or have very good (better than a 5th percentile) AAA PAP EPDs if they have not been tested. As I mentioned before we also PAP-test all of our bull calves at about 17 months of age along with possible replacement heifers. At the time of testing our bull calves have lived in our Development Center at 5,500 ft in a very large pen with a steep incline. Our heifers come directly off grazing at from 6,000 to 7,800 ft on the ranch, to be papped. Approximately 75% of the 2021 bull calves and 85% of our 2021 heifer calves papped lower than 44 mmHg. Actual PAP scores are included in the catalog and sale video descriptions of sale animals.

Papping heifers has a secondary benefit for us. This is the third year in which we have papped heifers. We are beginning to develop longitudinal data on the PAP performance of our cows and our sires. We are currently transitioning our cow herd to give it a younger average age, which means that we will have much more actual PAP data on our herd dams, which we will gladly share with our interested customers. You can learn more about our PAP program from the 2022 Sale Catalog, which can be requested at

26 views0 comments


bottom of page