A new look at lung ultrasound

by Gabe Middleton, DVM

What can you do in the future to ensure your heifers have maximum production? There are many factors involved. A very simplified approach would involve the genetic makeup of the calf and the environment which they are provided. The genetics of an animal do not change; however, expressions of genes can. Maternal cells in colostrum can turn on expression of good genes to set the stage for better health and productivity. Colostrum is critically important. Any literature on calf husbandry states this fact.

The environment of the calf and the level in which it is affected by diseases has a tremendous impact on future productivity. A calf with excellent genetics that endures significant disease is affected often long into the future. In other words, despite great genetics, this animal will not perform up to its potential. This article examines a rapidly growing technology, calf lung ultrasound, and how it fits into management of dairy heifers and ensures improved future productivity.

In the past, calf lungs were ausculted with a stethoscope by a veterinarian to diagnose bovine respiratory disease. This is not a very sensitive technique to determine the severity of pathology. Lung ultrasound is an excellent and easy way to see underlying lung disease. The basic idea behind lung ultrasound is that ultrasound waves bounce off air, forming an artifact on the ultrasound image that represents normal, air-filled lung tissue. When there is fluid such as pus or other inflammatory fluids present, that is easily visualized on the ultrasound screen as abnormal lung pathology.

Many dairy producers point the finger at group-housed weaned heifer barns as the source of pneumonia. While this is certainly a risky time in the heifer’s life, lung ultrasound has allowed vets to determine that a significant amount of lung disease is present in the pre-weaning phase. Some of this lung disease is subclinical, not manifesting itself until a stress occurs. Typically this stress is weaning and grouping with other heifers. I’ve heard some producers say, “Calves don’t get pneumonia in hutches or individual pens.” Nothing could be further from the truth.

Why does it matter? The obvious answer is that it costs money to treat calves for pneumonia. Respiratory disease also leads to culling and death. While those statements are certainly true, there is research that proves that lung consolidation (not necessarily even clinical pneumonia) leads to a reduction in first lactation milk production. In fact, it has been documented that calves without lung consolidation produce over 1,000 pounds more milk in the first lactation than those who have lesions. Finding calves with lung lesions early and treating with proper antibiotics is the best way to find that extra 1,000 pounds of milk.

Another benefit of lung ultrasound is being able to determine the extent of lung lesions and pinpoint when they are occurring. This will allow for a discussion on what management changes need to occur for prevention of lung pathology. This is perhaps the even greater benefit. The calves will perform up to their potential if these lesions never have to be addressed in the first place. The factors that are typically discussed in regards to lung lesion prevention are colostrum, nutrition, vaccination, sanitation, bedding and grouping. These are all excellent topics for discussion to improve calf health in general.

Keep record of lung scores based on a system that your veterinarian is comfortable with. There is more than one right way to make lung ultrasound scoring work for your farm. My clients typically have me scan calves around four- to six-weeks-old for the first time. They receive a second scan prior to weaning. If both scans are clean, the calf needs no follow up. If lesions are present and the calf needs treatment, follow-up scans to ensure lesions are cured are necessary. This is a very simplified approach, but it can work well for busy vets. Also work with your veterinarian on the proper drug(s) to treat calves with lung lesions.

Invest in the future and preserve your genetic progress by preventing and properly treating bovine respiratory disease in pre-weaned heifers. The procedure is incredibly quick and has become a staple of management on many progressive dairies. The dairies who have adopted the technology recognize that those heifers are the future, and future productivity must be maximized to remain a financially viable business.

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