Objective, Longitudinal Computed Tomographic Evaluation of the Metacarpal Condyles in Non-Lame Thoroughbred Racehorses^†

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Objective, longitudinal computed tomographic evaluation of the metacarpal condyles in non-lame Thoroughbred racehorses

The study reviewed effectively demonstrate how cone beam CT is effective in the detection of increased bone density in response to flat racing training in young thoroughbreds. By recruiting 40 horses at the start of the study, they compared Hounsfield units (HU) of CT sagittal sections of sagittal metacarpal grooves and middle of both condyles. It also compares the dorsal and the palmar aspect of the condyles. They conclude that training has the most adaptive bone response happens in the first 6 months, and that the medial condyle and the dorsal part are the areas with higher HU. Increasing number of racings starts and higher body weight:height ratio were also associated with higher HU.

The introduction is concise but presents the research background and importance of a standing easy advance imaging tool that can detect variations in bone density in normal and pathological conditions. The study protocol is well designed, and number of animals is adequate to produce significant data despite attrition of horses ending with only 8 horses at the final point scans. Statistical methodology seems to be adequate. Results and discussion are presented in a well-organized fashion. Figures are clear and help the reader interpret the results. Conclusions are well extracted from the overall results.

General negative or neutral comments about the study include the decreased novelty of the study due to recently publications with the same objective and with only minor differences in protocol (shorter study period, the use of a fan-beam CT, and selection of the measured area). However, the study presents some interesting new data, validates previous data in those publications, and it reflects a hard effort in making this research happen.

Specific comments:

The only minor error found in the manuscript is in line 211 where a sentence is misplaced.

The study reports that the highest area of HU is in the dorsal medial condyle but did not state which of the points of interest is the one that presents a higher difference in HU before and after training. Maybe this is because it was hypothesized that the whole bone remodels the same amount in all the areas of interest? This could be an easy analysis with time 3 minus time 0 HU in each area. And if no significant difference in between areas, you can state that the bone remodels as a whole organ equally in all areas, which might not be true in pathologic stress remodeling.

Supplemental files including the raw statistical data analyses might not be needed in the final publication.

Author Response

Authors are grateful to the Reviewer for the positive comments and helpful queries.

Comments 1: The study reviewed effectively demonstrate how cone beam CT is effective in the detection of increased bone density in response to flat racing training in young thoroughbreds. By recruiting 40 horses at the start of the study, they compared Hounsfield units (HU) of CT sagittal sections of sagittal metacarpal grooves and middle of both condyles. It also compares the dorsal and the palmar aspect of the condyles. They conclude that training has the most adaptive bone response happens in the first 6 months, and that the medial condyle and the dorsal part are the areas with higher HU. Increasing number of racings starts and higher body weight:height ratio were also associated with higher HU.

The introduction is concise but presents the research background and importance of a standing easy advance imaging tool that can detect variations in bone density in normal and pathological conditions. The study protocol is well designed, and number of animals is adequate to produce significant data despite attrition of horses ending with only 8 horses at the final point scans. Statistical methodology seems to be adequate. Results and discussion are presented in a well-organized fashion. Figures are clear and help the reader interpret the results. Conclusions are well extracted from the overall results.

General negative or neutral comments about the study include the decreased novelty of the study due to recently publications with the same objective and with only minor differences in protocol (shorter study period, the use of a fan-beam CT, and selection of the measured area). However, the study presents some interesting new data, validates previous data in those publications, and it reflects a hard effort in making this research happen.

Response 1: Thank you for your comments.  

 

Comment 2: The only minor error found in the manuscript is in line 211 where a sentence is misplaced.

Response 2: We apologise but we are not certain which sentence the reviewer is referring to.

 

Comments 3: The study reports that the highest area of HU is in the dorsal medial condyle but did not state which of the points of interest is the one that presents a higher difference in HU before and after training. Maybe this is because it was hypothesized that the whole bone remodels the same amount in all the areas of interest? This could be an easy analysis with time 3 minus time 0 HU in each area. And if no significant difference in between areas, you can state that the bone remodels as a whole organ equally in all areas, which might not be true in pathologic stress remodeling.

Response 3: We very much agree with the Reviewer that this is a very interesting point. We did consider analysing each region separately, however, this would have markedly reduced the power of statistical analysis. Subjective comparison can be made from the data presented in Table 2. We do not believe that the number of horses allows us to perform more meaningful detailed analysis.

 

Comments 4: Supplemental files including the raw statistical data analyses might not be needed in the final publication.

Response 4: We are happy either way, we will leave it to the Editor to decide.

Reviewer 2 Report

Comments and Suggestions for Authors

Overall, your study is well structured and clearly written. The topic is relevant and methods are nicely prescribed. It might be useful to expand the discussion regarding the substantial loss of horses by the end of study period and consider what kind of impact this may have had to results.

It would be interesting to read more details about variability in training programs and workloads between the horses during the study period. Some of this is in discussion, but including more information already in the method section could improve the clarity.

Overall, focusing on non-lame horses is a strong aspect of the study. The objective measurements are appropriate, and long-term follow up is a strength of this study. The combination of biomechanics and clinical interpretation is valuable.  

Author Response

Authors are grateful to the Reviewer for the positive comments and helpful queries.

 

Comments 1: Overall, your study is well structured and clearly written. The topic is relevant and methods are nicely prescribed. It might be useful to expand the discussion regarding the substantial loss of horses by the end of study period and consider what kind of impact this may have had to results.

Response 1: The limitation section has been expanded: ‘Some horses were lost to follow-up, which may have introduced selection bias; however, to our knowledge no horses left the study due to condylar pathology. Furthermore, the loss of horses reduced statistical power at later time points.’

 

Comments 2: It would be interesting to read more details about variability in training programs and workloads between the horses during the study period. Some of this is in discussion, but including more information already in the method section could improve the clarity.

Response 2: Detailed information was only available at the first examination, this has been added to 93-95. ‘When enrolled, 27 horses had been engaged in some form of training (for 3–16 weeks, mean 7.4, median 4); 26 were exercised in trot and one also in canter (no fast work).’

 

Comments 3: Overall, focusing on non-lame horses is a strong aspect of the study. The objective measurements are appropriate, and long-term follow up is a strength of this study. The combination of biomechanics and clinical interpretation is valuable.  

Response 3: Thank you for your comments.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I am Reviewing the paper entitled “ Objective, longitudinal CT evaluation of the metacarpal condyles in non-lame TB racehorses”.

General comment

I would like to congratulate the authors on a very well-conducted study. The manuscript is clearly written and the methodological approach is solid and carefully designed. In particular, the adoption of a well-defined and rigorous protocol for the acquisition of advanced diagnostic imaging data is commendable. Achieving such a level of methodological consistency is not always straightforward, especially when working with racehorses, and this represents a clear strength of the study.

Overall, I have very few concerns. Most of my comments are minor and mainly intended as suggestions that the authors may consider if they feel they could further improve the clarity or completeness of the manuscript. In general, however, the work is well executed and provides valuable information to the field.

 

Simple summary

No additional comments

Abstract

No additional comments

Introduction

Nice introduction. Clear aims and hypothesis. Could be nice to report also the use of PET scan in evaluation of fetlock joint in racehorses in this section to complete the use of CT.

M&M

Line 88: hyppometers? Or some other device? Clarify.

Line 88-89: clarify what type of equine weighting scale.

Line 104: could authors specify if in standing position the fetlock joint was in a neutral weightbearing position or if some degree of flexion were present during the acquisition of the images?

Statistical analysis

Line 169: look at the results section it seems that categorical variables are reported as frequencies (and proporzions [%] in table 1. I suggest to change the sentence in using frequencies and proportions (%). For vascular channels, lines 301 -307 only frequencies are reported, whereas the Statistical Analysis section indicates that these variables are presented as proportions. Including the corresponding percentages might improve consistency.

Line 199: include the value of the coefficient (Spearman’s rho) considered representing highly correlated variables.

The statistical analysis is thorough and well performed.

Results

Line 206: I suppose ….training and/or discontinuation…..

Discussion

Regarding the discussion section, the different aspects of the study are addressed appropriately. The discussion is well written, the limitations of the study are clearly acknowledged, and the results are interpreted and discussed in a thorough and balanced manner. Overall, the authors provide a comprehensive interpretation of their findings within the context of the existing literature.

Tables

Regarding the tables, I would suggest removing decimal places when they are not informative (e.g., values such as 120.0 or 50.0% could simply be reported as 120 and 50%).

However, I noticed that Supplementary Tables 1 and 2 appear to be directly exported from the statistical software, as suggested by the font and general formatting. In their current format the tables are somewhat difficult to follow, as the columns are not clearly separated and the overall layout is not particularly reader-friendly, especially for readers who may not be very familiar with statistical outputs. It might therefore be useful to reformat Supplementary Tables 1 and 2 into a clearer and more structured layout, similar to the presentation used in Supplementary Table 3, which is much more elegant and easier to read. Just a suggestion.

 

Figures

Nice images.

References

No comment

Author Response

Authors are grateful to the Reviewer for the positive comments and helpful queries.

 

Comments 1: General comment

I would like to congratulate the authors on a very well-conducted study. The manuscript is clearly written and the methodological approach is solid and carefully designed. In particular, the adoption of a well-defined and rigorous protocol for the acquisition of advanced diagnostic imaging data is commendable. Achieving such a level of methodological consistency is not always straightforward, especially when working with racehorses, and this represents a clear strength of the study.

Overall, I have very few concerns. Most of my comments are minor and mainly intended as suggestions that the authors may consider if they feel they could further improve the clarity or completeness of the manuscript. In general, however, the work is well executed and provides valuable information to the field.

Response 1: Thank you for your comments.

 

Comments 2: Introduction

Nice introduction. Clear aims and hypothesis. Could be nice to report also the use of PET scan in evaluation of fetlock joint in racehorses in this section to complete the use of CT.

Response 2: Thank you for this suggestion. We feel that discussing other diagnostic imaging modalities is beyond the scope of this manuscript. If we mentioned PET, we would then need to discuss MRI and scintigraphy too for completeness and this would not be directly related to the study.

 

Comments 3: M&M Line 88: hyppometers? Or some other device? Clarify.

Response 3: an aluminium measuring stick was used, an own brand of an equestrian shop. Adding this might not be necessary, but we are happy to do so if required.

 

Comments 4: Line 88-89: clarify what type of equine weighting scale.

Response 4: an electronic equine weighing scale was used (Rinstrum). ‘electronic’ has been added to the text. We can add the brand if required; we did not feel it was relevant enough.

 

Comments 5: Line 104: could authors specify if in standing position the fetlock joint was in a neutral weightbearing position or if some degree of flexion were present during the acquisition of the images?

Response 5: Positioning has been added to lines 111-112: ‘The imaged forelimb was placed on the couch in a partially flexed, non- or semi-weightbearing position.’

 

Comments 6: Statistical analysis

Line 169: look at the results section it seems that categorical variables are reported as frequencies (and proporzions [%] in table 1. I suggest to change the sentence in using frequencies and proportions (%).

Response 6: ‘frequencies’ has been added to the sentence.

 

Comments 7: For vascular channels, lines 301 -307 only frequencies are reported, whereas the Statistical Analysis section indicates that these variables are presented as proportions. Including the corresponding percentages might improve consistency.

Response 7: Percentages have been added to vascular channels (lines 340-347)

 

Comment 8: Line 199: include the value of the coefficient (Spearman’s rho) considered representing highly correlated variables.

Response 8: Spearman’s rho indicating high correlation has been added to the text.

 

Comment 9: The statistical analysis is thorough and well performed.

Response 9: Thank you.

 

Comments 10: Results

Line 206: I suppose ….training and/or discontinuation…..

Response 10: Thank you for spotting this mistake, the text has been amended.

 

Comments 11: Discussion

Regarding the discussion section, the different aspects of the study are addressed appropriately. The discussion is well written, the limitations of the study are clearly acknowledged, and the results are interpreted and discussed in a thorough and balanced manner. Overall, the authors provide a comprehensive interpretation of their findings within the context of the existing literature.

Response 11: Thank you for your comments.

 

Comments 12: Tables

Regarding the tables, I would suggest removing decimal places when they are not informative (e.g., values such as 120.0 or 50.0% could simply be reported as 120 and 50%).

Response 12: We would be happy to do so but as far as we are aware, consistency is preferred and therefore we would like to leave the table as it is.

 

Comments 13:

However, I noticed that Supplementary Tables 1 and 2 appear to be directly exported from the statistical software, as suggested by the font and general formatting. In their current format the tables are somewhat difficult to follow, as the columns are not clearly separated and the overall layout is not particularly reader-friendly, especially for readers who may not be very familiar with statistical outputs. It might therefore be useful to reformat Supplementary Tables 1 and 2 into a clearer and more structured layout, similar to the presentation used in Supplementary Table 3, which is much more elegant and easier to read. Just a suggestion.

Response 13: The Supplementary Tables have been reformatted.

 

Comments 14: Figures

Nice images.

Response 14: Thank you.