DAVID BERGELAND/Durango Herald
Even before the snow has melted from the meadows of his sprawling 300-acre ranch near Hay Gulch, Davin Montoya is testing the viability of his cattle to survive until next winter.
The longtime rancher spent this weekend measuring the blood pressure of more than 100 cattle to test for bovine altitude sickness, also called brisket disease. The disease affects cattle genetically unsuited for higher elevations, and in some cases it can be fatal.
The idea is to test every animal and cull those predisposed to the disease before they spread those genes to their offspring.
Tim Holt, an assistant professor and veterinarian from Colorado State University, created the identification test, called a pulmonary-arterial pressure test. He administers the test for ranchers across the mountain West and has performed 350,000 during 33 years.
He spent Sunday at Montoya’s ranch.
Under gray skies that threatened snow, Holt and his assistant Lisa Herrick pierced a small hole in each cow’s neck and guided a catheter through its jugular vein and heart to the pulmonary artery. The tube was attached to an electrical instrument that read the amount of constriction in the artery. The test shows how well the animal has adjusted to the thin, mountain air. If the pressure reading is low, the animal is unlikely to suffer from brisket disease.
In animals that are susceptible to the disease, decreased oxygen at higher elevations causes a restriction in the arteries, including those that supply blood to the lungs. The heart is forced to work harder to pump blood through the body. Over time, pressure builds in the arteries and eventually, the heart wears out and stops beating.
The pulmonary-artery testing is a valuable investment for ranchers. Losses from the disease can range from 30 to 40 percent in cattle that are imported from lower elevations and from 0.5 to 5 percent among those raised at higher elevations.
During Sunday’s testing, Montoya discovered six cows that were susceptible to the disease. The rancher said he will sell those animals for slaughter, but not for breeding.
Montoya said he likes to do the blood pressure testing early in the year.
“That’s just one of our processes to eliminate the undesirable ones,” he said. “The sooner we know, the sooner we can get rid of them.”
Staff photographer David Bergeland contributed to this report.