WHAT is PAP and Why Does it Matter.


Specifically speaking PAP stands for Pulmonary Arterial Pressures and it is a test that evaluates a cow or bull’s likeliness to contract high-mountain or brisket disease. University research has demonstrated that the physical characteristics that lead brisket disease, are highly inheritable.

Brisket disease has been historically tied to raising cattle above 5200 feet (although it does appear at lower altitudes) and is one of the most costly aliments plaguing high altitude cattle producers. Brisket disease has caused 30% death loss in multiple herds and is associated with abortions, still born calves, dead calves and smaller than average weanling calves. Brisket disease’s is most distinguishing characteristic is retained fluid in the chest area, leading to death.

Brisket disease is not truly a disease that can be passed from one animal in a herd to another, instead it is a terminal illness caused by highly inheritable traits in animals. If one cow is moderately prone to brisket disease and mates with a bull who is also moderately prone to brisket disease her offspring will be more than likely to be highly susceptible to brisket disease. Although none of the other calves may be prone to brisket disease her calf will be; and stands a high chance of not making it to weaning age.

Other symptoms of live cattle with Brisket disease are, lethargy, weakness, inability to rise, decreased appetite, collapse, diarrhea, bulging eyes, distension and pulsation of the jugular vein and swelling in the brisket.

Oxygen levels decrease as altitude increases, thus the higher that altitude we live at the harder our bodies have to work to insure they get enough oxygen to sustain the body. All animals including humans are affected by high altitude decreases in oxygen. In all animals the pulmonary artery to constricts, becoming narrower, making it harder for the heart to pump the same amount of blood through the lungs. This why human athletes benefit from training at high altitude, because their heart, lungs and pulmonary artery become more efficient at gathering oxygen from the air. However cattle, unlike humans, do not benefit from living at higher altitudes for three reasons. Cattles pulmonary artery constriction is more exaggerated than humans and other animals. Cattle have a small lung size to body weight ratio and the lungs do not allow free passage of air in between neighboring regions.

Over time the constricting of the cows blood vessels causes the walls of the pulmonary artery to thicken, thus requiring the heart to pump harder. If the vessels in the lungs become too thick the heart will pump hard enough to push fluid through the pulmonary artery walls. This fluid is what ends up in the chest cavity and causes the swelling in the brisket area. The heart eventually wears out from pumping through such a restricted flow area and the animal dies of heart failure.

Since brisket disease is caused by highly inheritable traits it can be controlled and eventually eliminated from any herd by appropriate genetic management. Historically we have relied on natural selection to either kill off animals with a high propensity for brisket disease, or prevent their offspring from populating the herd due to poor growth, abortion, or calf mortality. In today’s economic environment, natural selection is not economically viable. Thus we have Pulmonary Arterial Pressures testing in which a catheter is inserted into the pulmonary artery and an average pressure is taken in millimeters of mercury (mmHG). Thus the lower the PAP score the less prone the animal is to brisket disease. In order for the PAP test to be accurate the Pulmonary Arterial Pressures procedure needs to be conducted at 6500 feet on animals that have spent at least 21 days at that altitude, although PAP testing has demonstrated 75% accuracy on animals living between 5000 and 6500 feet.

Ranchers can use strict culling protocol on their cows and use properly PAP tested bulls, with appropriate PAP score to virtual eliminate any risk of Brisket disease. Bulls that are tested at above 6500 feet, when they are 18 months of age, should have a PAP score of 35 to 41mmHG. Animals that are tested at 12 months of age will score 1 to 2mmHG, lower than when retested at 18 months of age.

The industry average for Ranches above 7000 feet is for bulls to have a PAP score of 44mmHG or lower. Scores higher than 45mmHG increase your herds’ risk of brisket disease. It goes without saying that if your herd lives at higher altitudes than 7000 feet you will want to have bulls with even lower PAP scores. Any cows or bulls with a PAP score of 49mmHG or higher, have a high risk of developing Brisket Disease and should

At Lawson Angus LLC we PAP test all of our brood animals in order to insure that we are not perpetuating Brisket Disease characteristics. Our calves are born above 6500 feet and spend their entire life above 6500 before they are PAP tested by Dr. Jeremy ley at 12 months of age. The end result is accurate PAP test scores and animals that are designed to live at high altitude.

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