PAP is an indicator for animals with lower risk of developing high altitude disease (HAD), which in most cases results in congestive right heart failure. Researchers and veterinarians at Colorado State University (CSU) have been studying the HAD, more commonly known as brisket disease, and its onset for decades and have developed PAP tests in order to select animals to avoid pulmonary hypertension.

This disease, most commonly found in cattle living at elevations of 5,000 ft. or greater, is a result of cattle living in hypoxic environments challenging heart and lung function. Symptoms of the disease include lethargy, diarrhea, weakness, brisket edema, right heart failure and eventual death. High altitude pulmonary arterial pressure (PAP) predicts the genetic differences in PAP score with lower EPDs being more favorable.

A lower PAP EPD predicts a sire should produce progeny with lower pulmonary arterial pressures, decreasing the risk of contracting HAD, which is desirable. It is also important to remember that a PAP EPD is not a replacement for taking scores on cattle living at elevation. An animal may have good genetics to pass onto the next generation, but due to a life event, BRD for instance, their respiratory system may be damaged, causing them to lack the viability to survive at high altitudes.

Think of PAP in terms of scrotal size. Bulls may have the genetic potential to pass along larger scrotal size genetics, but scrotal (SC) EPDs are not a replacement for breeding soundness exams (BSE). Producers will not send a bull out without conducting a BSE, no matter how good his SC EPD is. The EPD can be valuable to select parents for the next generation with less risk. However, if a sire is to be taken to higher elevations to live, they should be tested themselves before doing so.

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