High altitude disease (Brisket Disease), which causes cattlemen at high altitudes serious problems through cattle losses, has been thoroughly studied.
Pulmonary arterial pressure (PAP) measures have been shown to be a very good indicator of susceptibility to brisket disease, and differences in PAP values have been shown to be highly heritable.
Cattlemen at high altitudes can use bulls with low PAP values to eliminate this problem from their herd. All bulls sold at the SJBRC are measured for PAP values.
BRISKET DISEASE - PULMONARY HYPERTENSION FACT SHEET
Brisket Disease, also known as High Mountain Disease or Pulmonary Hypertension, is one of the Rocky Mountain region's most costly diseases. The disease is the result of elevated pulmonary arterial pressures or pulmonary hypertension and generally affects animals less than one year of age residing at an elevation above 5000 feet.
Brisket Disease is caused primarily by an oxygen shortage; oxygen availability is 17% less at 5,000 feet than it is at sea level; 20% less at 6,000 feet, 26% less at 8,000 feet, and 31% less at 10,000 feet. The oxygen shortage at high elevations causes increased resistance to blood flow in small arteries in the lungs. The heart compensates for higher resistance by stretching and building up a higher pressure. The pressure can continue to build up until fluids leak out of the blood stream and collect in the chest cavity, the brisket, and other places. Eventually, the heart wears out and stops beating.
The losses from the disease can vary depending on the origin of the cattle. In cattle born and raised at high elevations, the losses tend to run from .5% to 5%. In imported or lowland cattle the losses can range from 30% to 40%.
Cattle differ in how they respond to oxygen shortage. Some cattle are able to tolerate high pressures for a longer period of time, while others die quickly. Brisket disease is not limited to one sex or breed. It affects both sexes and has been found across all breeds including crossbreds.
Research has shown that the heritability of Brisket Disease can be quite high, ranging from 42% to 77%. This indicates that cattlemen can successfully select against the disease by curing cattle with high pulmonary arterial pressures.
Pulmonary arterial pressures (PAP) are obtained by a procedure called "right heart catherization". In this procedure, a fine plastic tube is passed through a needle in the jugular vein, with blood flow into the upper right side of the heart (atrium), through a valve, into the lower right side (ventricle), through a valve, and into the pulmonary artery just short of the branches to the lungs. Pressure waves are observed on a heart monitor and the monitor gives a direct readout of the true average pressure.
The PAP test is the best indicator (tool) available to date for identifying animals predisposed to Brisket Disease. The test is not 100% and should not be used as such. Generally, cattle with PAP values greater than 50 are considered to be of higher risk and cattlemen should be cautious of using them at high elevations.
In efforts to cut losses to Brisket Disease, cattlemen should identify those animals, specifically bulls, with high pulmonary arterial pressures and cull them from the herd or if possible, move them to lower elevations. Many times cattle with high PAP measurements or even beginning to contract Brisket disease can be successfully relocated at lower elevations.