Pulmonary Hypertension in Ox: High-Mountain Disease and Brisket Disease

Pulmonary hypertension in oxen means blood pressure is abnormally high inside the arteries of the lungs. In cattle raised or worked at elevation, this problem is commonly called high-mountain disease or brisket disease. The condition develops when low oxygen in the lungs triggers narrowing of pulmonary blood vessels, making it harder for blood to move through the lungs.

Over time, that extra resistance forces the right side of the heart to pump against higher pressure. The right ventricle first thickens, then may enlarge and weaken. When that happens, fluid can leak into tissues, especially under the chest and brisket, and the animal can develop right-sided congestive heart failure.

Cattle are unusually susceptible compared with many other species. Their lung structure, relatively small lung capacity for body size, and inherited differences in pulmonary vascular response all appear to play a role. In practical terms, this means some oxen tolerate altitude well, while others become sick under the same conditions.

For pet parents and livestock caretakers, this is an emergency-leaning condition. Early recognition matters because once severe edema, collapse, or advanced heart failure develops, treatment options become limited.

The main trigger is low oxygen exposure, especially at higher elevations. In susceptible cattle, hypoxia causes pulmonary arteries to constrict. If that low-oxygen exposure continues for weeks, the vessel walls remodel and thicken, which further increases resistance and raises pulmonary arterial pressure.

Altitude is the classic risk factor, and disease risk rises in many herds above about 5,000 feet. However, altitude is not the whole story. Genetics strongly influence susceptibility, which is why some bloodlines develop problems more often than others. PAP score selection has become an important herd-management tool in high-country beef systems.

Other conditions that reduce oxygen delivery or damage the lungs can worsen or mimic the same process. Chronic pneumonia, heavy parasite burdens, cold stress, poor respiratory health, and other causes of long-term low oxygen can add strain to the pulmonary circulation. In feedlot cattle, similar right-sided heart failure syndromes have also been recognized at more moderate elevations.

Because several diseases can look similar from the outside, your vet will need to sort out whether the swelling and breathing changes are truly due to pulmonary hypertension or another heart or lung disorder.

Diagnosis starts with a careful history and physical exam. Your vet will ask about elevation, recent movement from low to high country, breeding background, respiratory disease history, and how long signs have been present. On exam, they may find brisket edema, jugular pulses, abnormal heart sounds, weakness, or increased breathing effort.

In herd and breeding settings, pulmonary arterial pressure (PAP) testing is the key tool used to identify cattle at higher risk. This test directly measures pressure in the pulmonary artery, usually by passing a catheter through the jugular vein. Higher PAP values suggest greater susceptibility, and cattle with PAP values above about 49 mm Hg are generally considered at particularly high risk in high-altitude systems.

Your vet may also recommend bloodwork, ultrasound, necropsy of herd losses, or additional testing to rule out other causes of edema and heart failure, such as traumatic pericarditis, myocarditis, endocarditis, severe pneumonia, or parasitism. In field conditions, diagnosis is often a combination of history, clinical signs, altitude exposure, and response to management changes.

Because this condition can overlap with other serious diseases, a veterinary diagnosis is important before making breeding, culling, transport, or treatment decisions.

Prevention focuses on matching cattle to environment. In herds that live or work at elevation, one of the most useful tools is selection for lower pulmonary arterial pressure (PAP) and avoiding breeding from animals known to be susceptible. PAP testing has been used for years in high-altitude cattle programs to identify animals that are more likely to tolerate mountain conditions.

Careful movement planning also matters. Cattle brought from low elevation to mountain pasture may be at higher risk, especially if they are large-framed, fast-growing, or from non-adapted bloodlines. Gradual acclimation may help with management, but it does not eliminate inherited susceptibility.

Good respiratory health supports prevention too. Work with your vet on vaccination plans, parasite control, nutrition, and prompt treatment of pneumonia or other lung disease. Anything that reduces chronic low oxygen stress may lower the chance that pulmonary hypertension will worsen.

If your operation has repeated cases, ask your vet about a herd-level strategy. That may include PAP testing, culling decisions, breeding changes, altitude-specific replacement selection, and necropsy of losses so future prevention is based on the most likely cause.