Over the past decade, bovine congestive heart failure (BCHF) has emerged as one of the biggest threats to the health and productivity of cattle on feed.

Kirk Ramsey

Professional Services Veterinarian / Neogen

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As this syndrome continues to grow, it has forced researchers and industry partners to dig deeper to uncover the vast complexities of heart health in cattle populations. Furthermore, the feeding industry has seen mortality rates as high as 7% in severely affected cattle pens, which can translate to over $250,000 in annual losses for a single feeding operation. These losses are only represented by cattle that have failed to reach the production plants and do not account for production losses associated with subclinical animals suffering from heart disease that drastically limits their ability to grow and produce. However, the most common and grievous losses are individuals who die of BCHF in the late stages of their feeding program. As a result, a significant amount of time, money and effort are lost as these cattle fail to reach their final destination.

It is key that, as an industry, we work together to take proactive steps to mitigate and correct the risk of BCHF. While we do not have full control and understanding of BCHF because of the complexities of the cardiac and pulmonary systems, we do know that the syndrome is being propagated by something selected for genetically – and that is something we can help control.

Understanding BCHF

First, we must understand that BCHF is a syndrome that boils down to the heart’s inability to pump enough blood to meet maintenance requirements. Sure, the cardiac system is overwhelmingly complex, but the basic premise is simple. The heart is a pump that has two priorities: 1) pump deoxygenated blood to the lungs and 2) then pump oxygenated blood from the lungs to the rest of the body. This system is a closed loop and, under normal conditions, works flawlessly. However, any change in the system that requires the pump (heart) to work harder – such as congestion in the arteries, shrinking of pulmonary vessels, lung pathology, etc. – will result in physical adaptations of the heart. Once the heart begins to adapt to these changes, a snowball effect can occur. The muscle fibers of the heart begin to grow, helping to pump blood through the congestion but decreasing how much blood the heart can hold in its ventricles. Over time, the blood cannot enter the heart like before and begins to slow the system down, adding further challenge to the heart. After a while, the added pressure from the blood in the ventricles of the heart begins to stretch the once-strong muscle fibers. This creates a ballooning effect on the ventricles of the heart and reduces the overall capacity for blood to flow, thus resulting in heart failure.

Symptoms of BCHF are broad and often go unobserved. However, when the disease has progressed long enough, the most apparent symptoms are associated with heart failure itself, which is manifested by these conditions:

• Edema in the brisket
• Excessive lethargy
• Extended neck and labored breathing
• Edema around the neck and a prominent jugular pulse

Genetic predisposition for BCHF

As research has progressed, there are still many gaps to be uncovered in fully understanding heart failure in cattle. We have much to learn about why fed cattle might be responding this way, although recent work has uncovered vital details regarding the genetic predisposition some cattle have for BCHF and its heritability among cattle populations. This implies that there are real opportunities to make strides by selecting against BCHF as a trait.

The level of variability for BCHF risk in a feedlot setting was recently observed in a case study by using our genomic selection tool, which assesses an animal’s genetic predisposition for BCHF and scores animals on a 1-to-10 scale, ranging from 1 (lowest risk of disease development) to 10 (highest risk). The data revealed up to a 17.7% difference in the likelihood of different animals experiencing BCHF. By genetically testing cattle, we can locate breeding stock at a high risk of bovine congestive heart failure. Then, we can make informed decisions to not breed those bulls to cows that might have the same type of risk. This gives us a way to work backward by breeding away from BCHF and not predisposing more cattle to the condition.

Managing BCHF risk

For cattle genetically predisposed to BCHF, tailoring feeding strategies to the higher-risk animal and following low-stress handling practices can help reduce their risk for heart failure. By genetically testing groups of cattle to determine their genetic risk, producers can more efficiently group animals for ease of management, and work with their nutritionist to develop rations and feeding strategies based on individual pen levels. The goal here is to keep cattle sound while also getting cattle with a higher BCHF risk to the packing plant earlier.

Additionally, it is important to reduce stress as much as possible and follow low-stress handling techniques to significantly help mitigate heart failure risk. Last, but certainly not least, ensure that people are properly trained to recognize early signs of BCHF to implement changes early in the syndrome progression.