HIGH ALTITUDE PULMONARY HYPERTENSION (BRISKET DISEASE, MOUNTAIN SICKNESS)

High altitude pulmonary hypertension, also known as brisket disease, is a significant cardiopulmonary disorder affecting cattle raised at elevations above 1500 meters.The condition develops primarily due to alveolar hypoxia, which induces pulmonary vasoconstriction and leads to a progressive increase in pulmonary arterial pressure.Cattle, particularly Bos taurus, exhibit one of the strongest vascular responses to hypoxia among domestic species, predisposing them to right ventricular hypertrophy, cor pulmonale,and congestive heart failure
Recent studies have identified a gain-of-function mutation in the EPAS1 gene, which stabilizes hypoxia-inducible factor 2α (HIF-2α).This genetic alteration enhances the hypoxic response and significantly increases the risk of pulmonary hypertension, especially in Angus cattle.The presence of both EPAS1 variants confers an even greater risk, emphasizing the interaction between genetic predisposition and environmental hypoxia.Interestingly, cattle harboring this mutation at low altitudes show no abnormal pulmonary pressures, confirming that disease development is contingent upon the gene–environment interaction
Epidemiologically, brisket disease occurs sporadically in mountainous regions of North and South America, as well as in the highlands of Ethiopia and India. Calves, yearlings, and late-pregnant cows are the most susceptible groups, particularly when newly introduced to high altitudes.Mortality rates are high unless animals are promptly relocated to lower elevations.Contributing factors such as myocardial dystrophy, anemia, pulmonary disease,and hypoproteinemia can exacerbate the condition.Ingestion of locoweed (Oxytropis sericea) has also been shown to potentiate cardiac failure at altitude, though the mechanism remains unclear
Clinically, affected cattle present with jugular distention, brisket and ventral edema, dyspnea, weakness, and cyanotic mucous membranes 

Necropsy typically reveals right ventricular dilation, hepatic congestion, and pulmonary emphysema

The only effective treatment is immediate movement to lower altitudes, as medical management is rarely economical for commercial herds
Control strategies include selection of animals with low pulmonary arterial pressures, avoidance of toxic plants such as locoweed, and genetic screening for EPAS1 mutations. However, genetic resistance to the disease is paradoxically associated with lower growth performance at low altitudes, complicating breeding programs.This condition remains a classic example of how genetic susceptibility and environmental stressors jointly determine disease expression in livestock

 : Reference
Veterinary Medicine, 11th Edition, Elsevier, 2017
Authors: Peter D. Constable, Kenneth W. Hinchcliff, Stanley H. Done, Walter Grünberg