May 7, 2020
Maureen Hanson
Despite significant advancements in ventilation, vaccines and antibiotics, we’re still weaning too many dairy calves with diseased lungs, according to Theresa Ollivett, Assistant Professor of Food Animal Production Medicine at the University of Wisconsin-Madison School of Veterinary Medicine.
Ollivett has pioneered the use of lung ultrasonography to evaluate lungs in calves and older dairy animals, shaping a management philosophy of #WeanCleanTM. Its mission: Use lung ultrasound to promote calf health management that maximizes every calf’s potential to begin and transition through the weaning process with clean, healthy lungs.
“Lung lesions can precede clinical signs by a week or more,” Ollivett told the audience of the recent Dairy Calf and Heifer Association Annual Conference. “On many farms, about 60 to 80 percent of lung infections are subclinical before calves exhibit symptoms.”
The researcher has developed a scoring system based on the number and size of lesions detected in each animal. She said lung lesions as small as 1 cm can affect calf growth, and lesions 3 cm or larger can impair first-lactation milk production by at least 1,200 pounds. “Many herds display 60 to 80 percent of calves with 3-cm lesions at weaning, with most of those cases largely undetected,” Ollivett noted. “That shows how significant and widespread the problem is.”
Cases that are not diagnosed early become more stubborn to treat, and some go unchecked with no detection or treatment. Clinical pneumonia often does not become apparent until calves endure the stress of weaning, when they break with full-blown illness that may have been smoldering for many weeks.
The #WeanCleanTM approach employs lung ultrasound scans at four strategic points:
Start of weaning – Goal: less than 15% with detectable pneumonia on ultrasound.
Start of treatment – Goal: less than 15% with moderate to severe pneumonia (lesion scores greater than “3”) at their first treatment.
7-10 days after treatment – Goal: less than 15% with lesion score greater than “2” after their first course of treatment.
12X7 scans – Starting at 7 days of age, scan 12 calves at 7-day intervals to identify high-risk age groups in the herd.
While regularly ultrasounding lungs is a significant management change, Ollivett said the scans take less than 1 minute per calf, and about 25 to 30 calves can be processed per hour. Proper training and veterinary oversight are important in interpreting and acting upon the ultrasound results.
“I think it is entirely realistic for dairies and contract growers to incorporate lung ultrasounds as a part of their routine management program,” noted Ollivett. “Weaning calves with clean lungs – and putting the monitoring and management in place to ensure that happens – is a huge piece of raising healthy and productive replacements that we have the ability to dramatically improve.”
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