Brisket Disease or High Mountain Disease (HMD) in cattle is due to hypoxic-induced pulmonary hypertension with subsequent fight ventricular failure. HMD is most commonly associated with cattle at elevations of greater than 6500 feet (2166 meters) and can result in annual losses of greater than 1-5%. In genetically susceptible herds the losses can greatly exceed this percent. Given the size of the beef cattle industry in Colorado and other mountainous states, these percentages represent a significant economic problem. The vascular changes in the bovine lung resulting in pulmonary hypertension seen in high altitude cattle appear to be genetically regulated by an autosomal dominant gene with possible reduced penetrance. A common denominator in the maladaptation to High Altitude living in cattle will manifest itself as an increase in pulmonary arterial pressure as a result of pulmonary hypertension. Therefore it is possible that genetically susceptible animals have an increased pulmonary artery pressure (PAP) reading. Measuring PAP's in the field has given the rancher a successful tool in selecting cattle genetically more resistant to pulmonary arterial hypertrophy, hypertension and HMD. Careful selection of artificial insemination sires and culling of susceptible cattle (those having an increased PAP measurement) has helped the rancher to dramatically reduce their losses due to HMD.