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Why ultrasonography could help you find what you’re missing

Theresa L. Ollivett Published on 10 October 2013
dairy calf

The University of Guelph has just completed the data collection phase of a large study designed to increase understanding of clinical and subclinical pneumonia and its long-term effects in dairy calves through the use of ultrasonography.

This study comes as a follow-up to a pilot project in which roughly 14 percent of calves with pneumonia showed minimal or no signs of illness.

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Unfortunately, identifying cases of subclinical pneumonia and measuring its effects are impossible without tools that specifically detect consolidated, pneumonic lung – such as ultrasonography.

Dairy producers and practitioners can work together and use the information gained from this study to evaluate both individual and groups of calves for pneumonia.

In the current study, Holstein calves were scanned by ultrasound weekly for the first 10 weeks of life using the same ultrasound as is used for reproductive exams in adult cattle.

This is the first study to assess the entire lung field for pneumonia by scanning the first- or second-to- the-10th rib space on both sides of the chest.

Calves were also evaluated for respiratory score, fecal score, weight and were blood sampled for measures of inflammation. Feed intakes and any treatments were also recorded.

As time goes on, information regarding breeding, calving and lactation will be collected on these animals.

Once fully analyzed, this data set will show the effect of pneumonia, scours or a combination of both problems on feed intakes, average daily gain, future reproduction and lactation performance.

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Additionally, a small group of bull calves were sacrificed and necropsied in order to confirm that the lesions seen on ultrasound were indeed evidence of pneumonia.

Preliminary findings suggest that ultrasound is very sensitive in detecting pneumonia regardless of the health status of the calf.

Many calves have a single large lesion under the first rib space on the right side. Scanning according to current literature excludes this location and will result in misdiagnosis of the individual calf and falsely low levels of disease in the herd.

Veterinarians can check a calf for pneumonia with a quick modified exam that scans both sides of the chest just under and behind the elbow in the first five rib spaces, which are the most common locations for pneumonia.

pneumonia calf lungLung abscesses, fluid around the lungs and broken ribs can also be diagnosed and might change treatment plan and prognosis for recovery.

Abscesses and fluid around the lungs are usually on a veterinarian’s radar but cannot be reliably confirmed without ultrasound.

Broken ribs are probably underdiagnosed by many dairy veterinarians as most do not cause any problems after the first 24 to 48 hours of life.

Occasionally, however, broken ribs can shift, puncturing the lung or heart.

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This can result in an acute death or respiratory distress and a misdiagnosis of pneumonia.

Once comfortable with ultrasonography, a veterinarian can make a reliable diagnosis of pneumonia in less than a minute per calf if the calf is properly restrained in a corner, against a hutch or in a headlock.

At the herd level, ultrasonography can provide a more accurate estimate of the level of disease as compared to treatment records.

Before and after counts of pneumonia can help the producer and veterinarian determine if a management change has actually improved the health of the calves.

Also, veterinarians can screen animals being bought or sold by producers. The producer can then choose to keep animals with normal lungs and no obvious signs of chronic disease.

Lastly, response to antibiotics can be monitored to ensure treatment protocols are functioning properly and resulting in resolution of lung consolidation.

Ultrasound clearly has uses on a dairy farm besides diagnosing pregnancy. The more we learn about the influence of respiratory disease on the success of future lactations, the more pressure there will be for earlier identification and intervention, either through management changes, treatment or culling.

The use of ultrasonography should reduce the inconsistencies in diagnosis, as well as promote general improvement in animal health. In addition, ultrasonography will serve to enhance our understanding of risk factors and the long-term impacts associated with pneumonia.  PD

PHOTOS
TOP: The calf pictured here, #241, appears to be a bright, alert and healthy calf.

MIDDLE: This image of the necropsy of calf #241 shows a different story. The lung area circled is consolidated, indicating pneumonia. Photos courtesy of Theresa Ollivett.

Theresa Ollivett  

 Theresa L. Ollivett
Department of Population Medicine
University of Guelph



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