Sunken flank: What does it mean and why is it important?

By Dr. Dave Renaud
ACER Consulting Ltd.

Research conducted at the University of Guelph has identified several metrics that can be used to identify calves arriving at veal facilities that are high-risk for future mortality and treatment for disease. Specifically, they have identified that calves arriving with an umbilical infection, dehydration, diarrhea, and low body weight are more likely to be treated and die. Another factor that was identified to be important in predicting future disease risk was the presence of a sunken flank.

What is a sunken flank?

Figure 1

A sunken flank is present when a calf has a hollow abdomen or depression in the paralumbar fossa. This is highlighted in Figure 1 where the area behind the rib cage is depressed inwards. A recent research study that evaluated almost 5,000 calves on arrival at a veal facility in Ontario found 20 per cent, or 991, arrived with a sunken flank, suggesting this is quite common in the industry.  

What is the impact?

In the Ontario study highlighted above, researchers found that calves with a sunken flank were more likely to die. Specifically, calves that had a sunken flank had a four times greater risk of dying in the first 21 days after arrival to the facility when compared to calves without a sunken flank. Another study conducted in Europe also highlighted the risk of a calf having a sunken flank at the beginning of the production cycle where calves with a sunken flank were two times more likely to die over the entire production period. Therefore, making sure that calves do not have a sunken flank upon arrival at veal facilities can help to reduce mortality.

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How does a sunken flank occur?

It is not completely clear how sunken flanks occur however it is thought that they develop over time when there is a long period of time between milk meals. As calves with little to no energy input have reduced disease resistance, this is likely the reason for the association between sunken flank and mortality. In addition, the presence of a sunken flank is further compounded by long transport times, where calves will expend additional energy to move and stay warm, leading to less energy to expend on fighting disease.   

Preparing your calves for transport to prevent sunken flank occurrence

It is important to feed calves as close to transportation as possible. A recent study identified that feeding milk immediately prior to transport can help calves to have better energy stores when arriving at a veal facility. This highlights the importance of feeding a high energy diet before transport, which can not only reduce the occurrence of a sunken flank but also lead to higher body weight at arrival thereby reducing the risk of disease.

It is important to prepare calves for their journey through the marketing system to better prevent not only the occurrence of a sunken flank but many other health abnormalities. Once calves leave the source dairy farm, ideally it is best if they are brought to a veal facility within a few hours. However, there are many calves that are marketed through auctions and transported for long periods of time, leading to a depletion of energy stores, exhaustion, and in the winter, chilling. To combat these challenges, when possible, try to establish local connections where calves are only in transit for a few hours prior to arriving at a veal facility. 

Take home messages

Sunken flanks are common in calves that arrive at veal facilities. The presence of a sunken flank in an arriving calf is associated with a much greater risk of mortality. Ensuring that calves receive a milk meal prior to transport is critical in improving disease resistance and preventing a sunken flank from occurring. In addition, identifying ways to reduce the time calves are in transit can also help to reduce the occurrence of sunken flanks.  

This project was funded by the Canadian Agricultural Partnership, a five-year federal-provincial-territorial initiative.