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Using lung ultrasound to promote calf health management

Theresa L. Ollivett for Progressive Dairy Published on 07 May 2021
lung ultrasound

How do you know if your calf-raising program is producing high-quality, healthy calves that are set up to meet their genetic potential for milk production in the future?

Maybe you look at the percent of preweaning calves that die or that get treated for scours or pneumonia. Perhaps you weigh calves and compare their average daily gain (ADG) between birth and weaning to industry standards. While morbidity, mortality and growth certainly have value as performance indicators, they don’t tell you the whole story, especially when it comes to respiratory disease or, more specifically, pneumonia.

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Pneumonia, a bacterial infection of the lung tissue, is a sneaky disease. Signs of illness are highly variable and range from no signs at all to heavy breathing, coughing, fever and severe depression. It’s also sneaky because little blips in colostrum management, or a bout of severe cold stress, or a milk pasteurizer malfunction not only increase the number of calves with scours, but they usually significantly increase the number of calves with subclinical pneumonia as well. A single case of pneumonia can last several weeks or months, so a couple of bad days on your farm could mean dozens or even hundreds of calves that will have to carry the metabolic burden of infected lungs with them to and through the weaning period. This burden means poor growth, greater risk of death and lower milk production down the road.

Successful calf programs will yield animals that reach weaning age and transition through the weaning process with ultrasonographically clean, healthy lungs. Weaning with clean lungs means these calves will be less likely to get sick and require treatment in the post-weaning period. If calves are weaning with pneumonia, this means we failed to identify them earlier, we failed to treat them properly, or the calves failed to respond to our appropriately administered treatments. This link between early life management and respiratory health serves as the basis for the #WeanClean program.

The #WeanClean program uses a 4-point ultrasound strategy to assess lung health and troubleshoot bottlenecks in management.

1. Start of weaning – How many have pneumonia at the start of weaning? Goal: less than 15%

2. Start of treatment – How many have severe pneumonia at their first treatment? Goal: less than 15%

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3. Seven to 10 days after treatment – How many still have pneumonia after their first treatment? Goal: less than 15%

4. 12 x 7 scans – Starting at 7 days old, scan 12 at seven-day intervals to find high-risk age group

If you determined your calves are not weaning with clean lungs, you have to step back and think about why that is happening. The first part of figuring this out is to assess detection and determine how severe disease is when calves are treated for the first time.

If calves have significant lung disease on ultrasound when they are treated for the very first time, then this suggests detection is poor. Poor detection allows more time for the pneumonia to worsen, making it harder to cure once treatment is administered. Once it’s clear that detection is an issue, you can start to investigate why. This might be because the caregivers are not looking at the right calves or they don’t know what signs to look for. More commonly, calves are affected by subclinical pneumonia and only show signs once disease has progressed in severity.

After assessing detection, the next step is to assess treatment response by reassessing calves seven to 10 days after they were treated for the first time. You can then compare their initial lung score on the day they were treated to their follow-up lung score seven to 10 days later. If lung scores are the same or worse, it indicates these calves are not responding appropriately to treatments. Common reasons for treatment failures include late detection, incorrect dosing of the correct drug, correct dosing of the incorrect drug or generalized poor immunity and failure to respond to appropriate treatment.

The fourth component of the program is called 12 x 7 scanning. 12 x 7 scanning refers to assessing 12 calves at seven-day intervals during one visit. For example, your veterinarian would scan 12 7-day-old calves, 12 14-day-old calves, 12 21-day-old calves, etc., until an obvious peak in lung lesions is observed. For many dairies, subclinical pneumonia develops as early as 14 to 21 days old. Understanding the age of onset for your farm will help you direct detection efforts and interventions intended to prevent pneumonia at the correct animals. Some dairies will then scan these high-risk age groups every week and implement first treatments based off the lung scores.

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#WeanClean can be used as a first step to how well your calves are traversing their first couple months of life. Following that, you can use it to determine if detection or treatment efficacy is contributing to excessive disease at weaning. You can also use it to determine who is most at risk of getting sick and if subclinical pneumonia is a big contributor to getting calves detected and treated as early as possible. end mark

PHOTO: If calves have significant lung disease on ultrasound when they are treated for the very first time, then this suggests detection is poor. Poor detection allows more time for the pneumonia to worsen, making it harder to cure once treatment is administered. Photo provided by Theresa Ollivett.

Theresa L. Ollivett
  • Theresa L. Ollivett

  • Assistant Professor, Food Animal Production Medicine
  • University of Wisconsin – Madison School of Veterinary Medicine
  • Email Theresa L. Ollivett

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