CALF_News_Feb_March_2019

22 CALF News • February | March 2019 • www.calfnews.net CALF ANIMAL HEALTH Chuteside Manner EXPLORING THE FRONTIER OF ANIMAL HEALTH Brisket Disease Is Creeping East By Patti Wilson Contributing Editor A couple previous Chuteside articles have focused on maladies creeping into beef herds from dairy segments of the U.S. cattle population. There’s yet another problem finding its insidious way from the Rocky Mountain area to the Plains. This one is not contagious, nor is it related to milk cows, yet its insistent increase in feedlots reminds us that health problems tend to spread in opportunistic manners, without discrimination. What is it? Pulmonary hypertension (PH) has been recognized and studied for over 100 years. Until recently, it has been confined to the high mountain areas of Colorado, Wyoming, New Mexico and Utah. Elevations over 5,000 feet are considered high risk, with the incidence of PH increasing as elevations increase. To put this as simply as possible, brisket disease is very nearly the equiva- lent of high blood pressure in humans. The thin air in mountainous areas contains less oxygen than lower eleva- tions; consequently, cattle hearts must work harder to supply oxygen to organs. Over time, the heart muscle begins to hypertrophy (thicken) to the point that it becomes inelastic and can no longer adequately contract to pump blood. This is basically a form of congestive heart failure. Blood pressure builds in the now-constricted artery that carries blood from the heart to the lungs, making for a poor prognosis. The particulars A heart that works too hard will spin off many problems. Specifically, the right side of the heart is responsible for pump- ing or pushing blood into the lungs. It is the most vital job within any animal’s body.With PH, a major artery carrying blood directly from the heart to lungs will respond to stress by narrowing, reducing blood flow and increasing blood pressure. The extra effort needed to pump blood through an ever-narrowing artery causes the heart wall to thicken or enlarge until it loses elasticity and effectiveness. It is a chicken-and-egg dilemma. Eventually, blood initially pumped into the constricted artery can flow back into the heart and blow out the valve of the right ventricle. As the disease progresses into the lungs, hypertension causes fluid to leak from blood vessels into the body, causing a swollen bris- ket. The swelling or fluid retention can extend behind the brisket into the belly and up into the neck area. In all cases, this leads to death. Absent of fluid retention, other signs may include difficult breathing, lethargy, bulging eyes, diarrhea and weakness. After listing all these symptoms, one can still find PH cattle lying dead, having had no symptoms at all. Who’s susceptible? Out of all mammals, cattle are the most likely to contract PH. Accord- ing to Dr. David Smith, University of Nebraska-Lincoln (UNL) Extension veterinarian, younger, faster-growing cattle are more at risk than mature or lower-performing stock. Obesity and lack of conditioning to altitude as well as a history of pneumonia or heart disease are detrimental. Cold temperatures (below 32° F) are hard on cattle, and, most surprisingly, feeding ionophores can also increase trouble. What does this have to do with us? Brisket disease is creeping down to lower elevations. Specifically, it is becom- ing more common in Nebraska feedlots, especially in the panhandle, where the elevation is just below 4,000 feet. The Nebraska problem was first documented in 1975. Dr. Smith says a death loss of 2 per- cent from PH alone is likely in a panhan- dle feedyard. This is similar to mortality rates with cattle living in high altitudes. The Merck Veterinary Manual indicates