Thoracic ultrasound is a diagnostic tool which can be easily utilized on farm to gain additional information about pulmonary pathology in dairy calves

Thoracic Ultrasound Article

Thoracic ultrasound is a diagnostic tool which can be easily utilized on farm to gain additional information about pulmonary pathology in dairy calves. The purpose of my investigation was to combine Dr Sheila McGuirk's calf respiratory scoring chart, thoracic auscultation, and thoracic ultrasound to evaluate 15 dairy heifer calves.

Calf Respiratory Scoring Chart

The calf respiratory scoring chart was utilized as it is on farm by trained personal – assigning a score for 5 different categories: rectal temperature, cough, nasal discharge, eye scores, and nose score – and adding the numbers to end with a Total Respiratory Score for each calf.  Score values of 4 are considered an animal which needs careful observation while scores of 5 or higher requires treatment based off existing farm protocols.

 

Thoracic Auscultation

Thoracic auscultation has been shown in multiple studies to lack specificity and sensitivity in diagnosing pulmonary pathology but is widely used in dairy calf evaluation. To systematically evaluate the thorax through auscultation, the chest can be divided into 4 quadrants based off those used by Buczinski and her 2014 research “Comparison of Thoracic Auscultation, Clinical Score, and Ultrasonography as Indicators of Bovine Respiratory Disease in Preweaned Dairy Calves.” For my purposes the thoracic was divided as shown below and each quadrant (A, B, C, D) on both the right and left were evaluated for presence of any abnormalities including crackles, wheezes, pleural fiction rub, absence of respiratory noise, or normal.

Thoracic Ultrasound

Ultrasound has been shown to improve specificity and sensitivity in evaluation of pulmonary pathology. Each calf in my investigation was scanned with the BCF ultrasound using a rectal probe and alcohol to flatten the hair. The thoracic images were evaluated for abnormalities including:

  1. Presence of comet-tail artifacts
  2. Number of sites with comet tail artifacts
  3. Pleural fluid accumulation
  4. Pleural irregularity (pleural lines separated) + depth of consolidation
  5. Normal

One image was obtained from both the right and left as a representative image for each side of the thorax.

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4609

4-8-17

0

1

0

102.0

3

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

  • Right Side – normal pleural surface                
  •   Left Side – normal pleural surface

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4610

4-9-17

0

2

0

102.0

4

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – normal pleural surface  

 

Left Side- normal pleural surface

                    

 Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4611

4-9-17

0

0

0

102.1

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – normal pleural surface  

Left Side – normal pleural surface

 

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4612

4-10-17

0

0

0

102.0

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

  • Right Side – normal pleural surface 

  • Left Side – normal pleural surface

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4613

4-10-17

0

0

2

102.1

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – normal pleural surface

 

Left Side – normal pleural surface  

                      

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4614

4-11-17

0

0

0

102.1

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

  • Right Side – comet tails              

   

  • Left Side – comet tails

 

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4616

4-12-17

0

0

0

101.5

1

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

  • Right Side – normal pleural surface   

  • Left Side – normal pleural surface

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4617

4-13-16

0

0

0

102.4

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

  • Right Side – comet tail              

    

  • Left Side – normal pleural surface

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4618

4-13-17

0

0

0

102.3

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – normal pleural surface      

                        

Left Side – normal pleural surface

 

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4619

4-14-17

0

1

2

102.1

5

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – comet tail and pleural thickening                  

Left Side – normal pleural surface

      

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4620

4-14-17

0

0

0

102.4

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – normal pleural surface

Left Side – normal pleural surface

                   

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4621

4-14-17

0

1

0

103.1

4

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – comet tail      

Left Side – normal pleural surface       

 

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4622

4-14-17

0

0

0

102.7

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – comet tail and pleural thickening

 

Left Side – comet tails

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4623

4-14-17

0

0

0

102.3

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – comet tail    

Left Side – comet tail

 

Respiratory Score

Animal ID

Birth Date

Nasal Discharge

Eye or Ear (highest number)

Cough – spontaneous or induced

Temperature

Total Respiratory Score

4624

4-15-17

0

0

0

102.0

2

Thoracic Auscultation

  • Normal

Thoracic Ultrasound

Right Side – comet tail    

Left Side – comet tail

Conclusions:

In my evaluation of this set of heifer calves, clinically they all appeared normal (except for several elevated temperatures, attributed to the extremely hot day). Similar to other studies I found thoracic auscultation to lack a lot of sensitivity and specificity. All the calves auscultated the same despite varying degrees of differences including comet tails and pleural irregularities as my most common findings. This indicates to me the differences in the pulmonary pathology of these calves which is not detectable through auscultation but recognized only with ultrasound imaging.

 

Through this project, I also found an appreciation for the technique required to image the thorax. Although images are easily obtained, forming quality images for interpretation, as well as understanding clinical relevance requires a little more work. In my experience, liberal amounts of alcohol as well as slightly older calves (larger rib spaces) enabled me to learn the best technique for scanning both sides of the chest efficiently and to produce quality images. As far as clinical relevance, I believe this area requires more investigation. All of these calves clinically appear normal, but still show differences with the ultrasound, in my opinion only time will tell if there are truly production differences in these heifers. Additionally, external factors will affect these heifers throughout their life which may or may not limit their production.

 

Overall, I find the ultrasound is an efficient way to evaluate the chest and obtain information beyond auscultation and physical appearance. However, long term production outcomes comparing calves with varying pulmonary pathology are still necessary before I’d be willing to make any decisions on the potential consequences of pathology seen in these calves.

 

 

 

 

 

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