By Lindsay King
The heart is a muscle and when it has to work harder, the organ will eventually remodel itself. This is the case in cattle suffering from high altitude sickness (HAS), sometimes known as brisket disease or bovine high-mountain disease (BHMD).
This topic was covered in the second innovation workshop sponsored by Neogen at the fifth-annual Angus Convention hosted in Columbus, Ohio, Nov. 3-5, 2018. Hannah Garrett, Neogen territory manager based out of Wyoming, explained the finer details of HAS and how it is possibly trickling down to lower elevation feedlots.
“From a physiological standpoint, this disease is a result of a progressive increase in arterial vasoconstriction due to vascular smooth muscle hypertrophy and a somewhat fixed obstruction of the pulmonary arteries,” Garrett added.
The heart works harder and builds muscle obstructing blood flow, making the vein smaller to push the blood through.
No one breed is more susceptible than any other. Risk factors include age, environment the animal was raised in and previous health issues. Animals with a high incidence of bovine respiratory disease (BRD) historically showed increased risk for the disease when tested in a high-altitude environment.
“[Pulmonary Arterial Pressure] PAP testing is an indicator of resistance to blood flow through the lungs and when measured at a high altitude is a reliable predictor of susceptibility of an animal for brisket disease,” Garrett said.
Making strides for helping for high-altitude producers is Colorado State University’s (CSU) Tim Holt, associate professor of clinical sciences in the College of Veterinary Medicine and Biomedical Sciences. His research revealed the heritability of a PAP score is 0.34.
“The best way to manage risk is to use proven bloodlines, purchase PAP-tested bulls, PAP-tested females and immediately haul at-risk animals to lower elevations,” Garrett said. “Producers send animals up to the mountains to graze and some of them never come back. They figure this into their death loss every year.”
The procedure for obtaining a PAP score seemed simple during the live demonstration by Dillon, Mont., veterinarian Ben Abbey. The small number of veterinarians performing PAP tests around the country either have ties to or were trained by Holt, including Abbey.
“I always tell the cowboys they need to have the chute as tight as your cinch, with enough room to slide your hand in by their neck and on their side,” Abbey said as he tied the heifers head around to the left side of the chute.
It’s important for PAP testing to occur at the elevation closest to the altitude where the animals will be expected to survive and thrive. Since a needle is inserted directly into the heart, sanitation during this process is of the utmost importance.
“We use a 3-inch, 12-gauge needle so our catheter can flow into it,” Abbey explained of the process he took less than five minutes to perform. “This is about the same as a cardiac catherization in people.”
Abbey inserts the needle into the jugular vein, feeding the catheter back through the right atrium and right ventricle to get into the pulmonary artery. The catheter is connected to a pressure transducer to measure PAP. The PAP score is derived from the mean of the systolic and diastolic pressure.
“The test has about a 75-95% repeatability when done at the proper elevation,” Abbey said. “Though you do have to take the age of the animal into consideration. I usually tell producers to test at or after sexual maturity.”
The average cost of a PAP test is under $30 per animal, plus the farm call charge. With cooperative cattle and an expert hand like Abbey’s, a PAP test is a quick way to save cattlemen a lot of trouble.