Internet-based survey on diagnosis and treatment recommendations for medial shoulder syndrome and instability in dogs

Abstract

Objective

The aim of this study was to document perceived frequency of medial shoulder syndrome and instability (MSS/MSI) among dogs, and preferred diagnostic and treatment options related to the condition, among American or European Colleges of Veterinary Surgeons (ACVS/ECVS) diplomates, American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR) diplomates, and dual diplomates of ACVS/ECVS and ACVSMR (double-Boarded diplomates).

Procedure

An invitation to complete an online survey was sent to diplomates via email listservs.

Results

The known response rate for the survey was 15.8% (160 of 1014 email addresses). There was a difference (P = 0.006) among groups in number of cases of MSS/MSI seen, with ACVS/ECVS diplomates and double-Boarded diplomates seeing 0 to 5 cases per year (80.7 and 72.7%, respectively) and ACVSMR diplomates (32% of total respondents) seeing 11 to 26+ cases annually. The majority of all respondents (56.4%) felt the likely cause of MSS/MSI to be chronic/repetitive strain. Diagnostically, most respondents (78%) relied on shoulder abduction angles; however, most felt it was a questionable or somewhat accurate diagnostic test. The ACVSMR diplomates (88%) relied on musculoskeletal ultrasound as their preferred diagnostic modality, compared to only 35% of ACVS/ECVS diplomates and 45% of double-Boarded diplomates. Preferred treatment was rehabilitation with surgery for unresponsive cases, as reported by 86.9% of all respondents. Preferred surgical treatment was prosthetic ligament reconstruction (62.7%).

Conclusion

Despite the low known response rate of this survey, there were significant differences among specialties regarding frequency of MSS/MSI cases seen per year and preferred diagnostic modalities. However, there were no differences among specialties regarding the suspected underlying causes of MSS/MSI and initial treatment strategies.

INTRODUCTION

Shoulder injury in dogs was first described by Bardet nearly 25 y ago (1). Since then, there has been a paucity of publications regarding shoulder injuries as compared to other common orthopedic conditions. Most recent studies have stemmed from surveys on injuries in agility dogs. Three published studies identified shoulder injuries as the most common injury sustained by dogs participating in agility (2–4). These surveys would suggest that diagnosis of shoulder pathology is increasing, most notably in agility dogs. However, there are apparently no published studies on the frequency of shoulder instability in canine patients.

In the veterinary literature, various diagnostic tests have been described for shoulder instability (5–15), including orthopedic examination identifying findings of discomfort (12), shoulder abduction angles (7–10,14), radiography (10,13), musculoskeletal ultrasound (MSK US) (8–10), CT (8), MRI (15), and arthroscopic evaluation, including both traditional and needle arthroscopy (8–12,16). Several of these diagnostic tests have questionable sensitivity or specificity and there is no single diagnostic test that has been clearly identified as superior; however, arthroscopy is considered the “gold standard” for visualization of the medial aspect of the shoulder (8–12).

Various treatment options have been described for conditions of the medial shoulder, including rehabilitation therapy (8,9), intra-articular platelet-rich plasma or other orthobiologics (8), radiofrequency-induced thermal capsulorrhaphy (RITC) (6,8,9,17–19), biceps tendon transposition (20), and numerous prosthetic ligament reconstruction techniques (21–30). No one treatment has proven superior to others as a preferred general standard of care. Of the current surgical treatments, prosthetic ligament reconstruction most consistently produces a good outcome, whereas a treatment such as RITC has a success rate similar to that for nonsurgical management (5,26).

Our primary objective for this study was to determine the perceived frequency and preferred diagnostic and treatment options relating to canine medial shoulder syndrome and instability (MSS/MSI) among diplomates of the American or European Colleges of Veterinary Surgeons (ACVS/ECVS), diplomates of the American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR), or dual-diplomates of either College of Veterinary Surgeons and the College of Veterinary Sports Medicine and Rehabilitation, hereafter referred as “double-Boarded diplomates.” We hypothesized that there are differences among groups: i) in the perceived frequency of MSS/MSI, with surgeons perceiving the prevalence to be low and sports medicine and rehabilitation diplomates perceiving the prevalence to be high; ii) with regard to diagnostic preferences; and iii) with regard to treatment preferences.

MATERIALS AND METHODS

A pilot questionnaire was developed by the 4 study authors (Appendix 1, available online from: www.canadianveterinarians.net). The questionnaire was then sent to a panel of individuals with recognized expertise in MSS/MSI, including diplomates from ACVS, ECVS, and ACVSMR. The intention of the questionnaire was to identify Board certification status; diagnostic testing preferences; perceptions regarding clinical usefulness and accuracy of diagnostics; treatment preferences; and perceptions regarding efficacy, safety, and technical difficulty of treatment options. To encourage participation, the survey was designed to be brief and, after feedback from the pilot questionnaire, a maximum of 11 questions were included. This study was reviewed and approved by BluePearl Specialty and Emergency Pet Hospital Institutional Review Board.

The survey was distributed by electronic mail to members of the Veterinary Arthrology Association listserv and the orthopedic listserv administered by Colorado State University, and those in the email database of ACVSMR active members. A cover letter accompanied the survey to explain the goals of the study and the time frame for completion and provide an assurance of anonymity. In addition, each participant was provided a link to the online survey (Survey Monkey; Palo Alta, California, USA: www.surveymonkey.com). The survey was launched on March 1, 2020, and remained open for 21 d. Two reminder emails were sent at 7-day intervals. Respondents were asked to identify Board certification status and asked questions regarding number of cases seen, diagnostic preferences, surgical preferences, and opinions regarding perceived efficacy/value of available techniques. Participants were asked to complete the survey even if they rarely or never see MSS/MSI in their practices. To ensure anonymity, email addresses were not saved with survey responses and respondents did not provide identifying information.

For a response to be included in the data analysis, the respondent had to indicate whether they were a member of ACVS, ECVS, ACVSMR, or either ACVS/ECVS and ACVSMR (double-Boarded diplomate) and the questionnaire had to be completed in its entirety. Any incomplete survey responses were excluded from data analysis.

Statistical analyses used descriptive statistics calculated and stratified by diplomate type. X² tests (Pearson X², likelihood ratio, linear-by-linear association) were done on the majority of data sets. “Likert-like” response sets were analyzed via the Kruskal-Wallis test. Post hoc tests (Mann-Whitney U and Wilcoxon rank-sum) were applied where appropriate based on a significant main effect between groups. For all analyses, P < 0.05 was considered statistically significant.

RESULTS

The survey was distributed to 1014 email addresses and received 160 responses (15.8% known response rate). Of the respondents, 70.6% were Board-certified by ACVS (92/160) or ECVS (22/160), whereas 15.6% were Board-certified by ACVSMR (25/160), and 13.8% were Board-certified by both ACVS/ECVS and ACVSMR (21/160).

Regarding the number of MSS/MSI cases seen per year, ACVSMR diplomates reported seeing more cases compared to ACVS/ECVS diplomates and double-Boarded diplomates (P = 0.006; Figure 1). Furthermore, 80.7% of ACVS/ECVS and 72.7% of double-Boarded diplomates reported seeing 0 to 5 cases of MSS/MSI per year, whereas 40% of ACVSMR diplomates reported seeing 0 to 5 cases per year. Of those seeing 11 to 26+ cases per year, ACVSMR diplomates reported a 32% frequency, versus 7.1% for ACVS/ECVS and 13.6% for double-Boarded diplomates (Figure 1). Of cases seen yearly, 54% of all respondents felt that most were chronic in nature, versus only 9.3% noting the cases seen per year were acute injuries. Furthermore, 56.4% of respondents reported the likely cause of MSS/MSI to be chronic trauma/repetitive strain, whereas only 12.8% reported acute trauma and 30.8% reported a combination of both chronic trauma/repetitive strain and acute trauma as the likely causes.

FIGURE 1.

Approximate numbers of cases of chronic or acute shoulder instability or luxation seen in a year. Green represents 0 to 2 cases per year, dark blue represents 3 to 5 cases per year, yellow represents 6 to 10 cases per year, light blue represents 11 to 25 cases per year, and orange represents 26+ cases per year. Significance of American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR) diplomates compared to both American College of Veterinary Surgeons/European College of Veterinary Surgeons (ACVS/ECVS) diplomates and double-Boarded diplomates in regard to numbers of cases seen per year.

Respondents were asked their preferred diagnostic methods for MSS/MSI and allowed to select all that applied. Diagnostically, 78% of all respondents relied on shoulder abduction angles to assist in diagnosis of MSS/MSI (Table 1). Other examination findings were noted by 51% of respondents and included pain on manipulation of the shoulder, discomfort when assessing abduction angles, radiographs (stressed and standard), and CT. Furthermore, 53% of all respondents relied on arthroscopy, whereas 45% and 28% relied on ultrasound and MRI, respectively (Table 1). There was a fairly even distribution of specialties recommending arthroscopy as the preferred diagnostic modality (ACVS/ECVS: 51%, ACVSMR: 44%) (Table 1). Among specialties, ACVSMR diplomates used ultrasound (88%) more often (P < 0.001) as their preferred diagnostic modality, compared to ACVS/ECVS (35%) and double-Boarded diplomates (45%) (Table 1). For MRI, double-Boarded diplomates (P = 0.04) used this modality 45% of the time, compared to 28% for ACVS/ECVS and 12% for ACVSMR diplomates (Table 1).

TABLE 1.

Preferred diagnostic methods for medial shoulder syndrome and instability in dogs.

	Shoulder abduction angle	Other physical examination findings	Arthroscopy	Ultrasound	MRI	Total
Q1: ACVS (A)	80.2% (73)	48.4% (44)	46.2% (42)	35.2% (32)	33% (30)	137.3% (221)
Q1: ECVS (B)	72.7% (16)	36.36% (8)	72.3% (17)	36.4% (8)	13.6% (3)	32.3% (52)
Q1: ACVSMR (C)	84% (21)	68% (17)	44% (11)	88% (22)	12% (3)	46% (74)
ACVS/ECVS and ACVSMR (D)	68.2% (15)	63.6% (14)	72.7% (16)	50% (11)	45.4% (10)	41% (66)
Total respondents	125	83	86	73	46	161

ACVS — American College of Veterinary Surgeons diplomates; ACVSMR — American College of Veterinary Sports Medicine and Rehabilitation diplomates; ECVS — European College of Veterinary Surgeons diplomates.

When asked about the perceived accuracy of currently available diagnostic testing, most respondents felt that it was questionably accurate and reliable or somewhat accurate and reliable (40.6 and 50%, respectively). Within specialties, AVCS/ECVS (52.6%) and ACVSMR (60%) felt currently available diagnostic testing was somewhat accurate and reliable, compared to only 23% of double-Boarded diplomates. Furthermore, 57% of double-Boarded diplomates felt that the currently available diagnostics were of questionable accuracy and reliability, compared to 41% of ACVS/ECVS and 24% of ACVSMR diplomates.

Regarding preferred treatment strategy, 86.9% of all respondents recommended rehabilitation as the primary treatment and surgery only for unresponsive cases (65.8%), or additional rehabilitation and/or medical therapy (21.1%). Only 1.9% of respondents recommended rest and oral medication alone, whereas 2.5% recommended some form of orthobiologic (platelet product or stem cell therapy) and 8.7% recommended surgical intervention. Sixteen percent of ACVSMR diplomates recommended some form of orthobiologic, compared to 0% of ACVS/ECVS or double-Boarded diplomates (Figure 2).

FIGURE 2.

Preferred treatment strategies for most cases of medial shoulder syndrome/medial shoulder instability (MSS/MSI) as reported by diplomates of American College of Veterinary Surgeons/European College of Veterinary Surgeons (ACVS/ECVS), diplomates of American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR), or double-Boarded diplomates. Green represents no treatment, dark blue represents rest and oral medication alone, yellow represents rehabilitative and/or medical therapy, light blue represents surgical intervention, orange represents rehabilitation and recommend surgery for unresponsive cases, and purple represents use of orthobiologics. Note that most respondents selected rehabilitation and recommended surgery for unresponsive cases.

Regarding preferred surgical treatment, 62.7% of respondents (Figure 3) chose some form of prosthetic ligament reconstruction, with 48.4% choosing open stabilization by prosthetic ligament reconstruction and 14.3% choosing arthroscopic or arthroscopic-assisted prosthetic ligament reconstruction. Open stabilization by tendon transposition was chosen by 9.9% of respondents, open stabilization by primary reattachment was chosen by 2.5%, and RITC was chosen by 8.7%. Among specialties, 24% of ACVSMR diplomates chose RITC, compared to only 6% of ACVS/ECVS and 9.1% of double-Boarded diplomates (P < 0.001) (Figure 3). Regarding stabilization by prosthetic ligament reconstruction, 58.5% of ACVS/ECVS and 50% of double-Boarded veterinarians chose to perform this open, compared to 0% of ACVSMR diplomates.

FIGURE 3.

Preferred surgical treatments for cases of medial shoulder syndrome/medial shoulder instability (MSS/MSI) as reported by diplomates of American College of Veterinary Surgeons/European College of Veterinary Surgeons (ACVS/ECVS), diplomates of American College of Veterinary Sports Medicine and Rehabilitation (ACVSMR), and double-Boarded diplomates. Green represents radiofrequency-induced thermal capsulorrhaphy (RITC), dark blue represents open stabilization by tendon transposition, yellow represents open stabilization by prosthetic ligament reconstruction, light blue represents open stabilization by primary reattachment, orange represents arthroscopic or arthroscopically assisted prosthetic ligament reconstruction, and purple represents other options that respondents could specify. Significance in ACVSMR diplomates preferring RITC compared to ACVS/ECVS and double-Boarded diplomates.

Of the currently available rehabilitation therapies and medical treatment options, 96.3% of respondents reported it was either sometimes safe, efficacious, and reliable (51.9%) or mostly safe, efficacious, and reliable (44.4%). Only 3.8% of respondents reported the currently available rehabilitative and medical treatment options were usually not safe, efficacious, or reliable. Finally, none of the respondents reported the currently available rehabilitative and medical treatment options were not useful at all.

Regarding surgical treatment options, 86% of all respondents reported that these were somewhat safe, efficacious, and reliable (66%) or mostly safe, efficacious, and reliable (20.1%); whereas 13.8% reported surgical treatment was usually not safe, efficacious, and reliable. In addition, 55.4% of respondents deemed the available surgical treatment techniques complex and somewhat difficult to execute, but effective; 25.5% of respondents deemed surgical techniques highly complex and very difficult to execute and indicated they do not feel comfortable or confident with the procedures; and 11.5% deemed surgical techniques straightforward and easy to execute. Only 7.6% of respondents indicated that available techniques are mostly unachievable and they try to avoid surgery. Regarding specialties, 40% of ACVSMR diplomates judged currently available surgical techniques mostly unachievable and indicated they try to avoid surgery, whereas 3.5% of ACVS/ECVS and 0% of double-Boarded diplomates judged surgical techniques mostly unachievable and indicated they try to avoid surgery (P < 0.001).

DISCUSSION

As the diagnosis of shoulder injury appears to be common based on the most recent internet-based surveys in agility dogs (2–4), it is important that veterinarians understand the frequency, diagnostics, and treatment options. In this manuscript, we provide quantitative data based on perceived demographics for MSS/MSI from 3 separate groups representing 2 veterinary specialties. Given that both specialties can be involved in dealing with MSS/MSI, demographic data between specialties is needed. Results from the present survey supported our first hypothesis, that there is a difference in perceived frequency of MSS/MSI between ACVS/ECVS diplomates and ACVSMR diplomates, with ACVSMR diplomates reporting a higher frequency of seeing cases of MSS/MSI. With this hypothesis, double-Boarded diplomates responded similarly to ACVS/ECVS diplomates.

Of veterinarians that reported seeing 11 to 26 MSS/MSI cases per year, ACVSMR diplomates were more than 4× as likely to see this number of cases compared to ACVS/ECVS diplomates or double-Boarded diplomates. Most ACVS/ECVS or double-Boarded diplomates reported seeing < 5 cases annually. This discrepancy may be higher as the total number of ACVSMR respondents was lower than the total number of ACVS/ECVS respondents. The difference in reported frequencies of annual cases could be explained by a difference in caseload selection, due either to clinician preference or confidence seeing forelimb lameness, or to clientele seeking the opinion of an ACVSMR diplomate for nonspecific forelimb lameness or perceived performance issues of a sporting dog. Another explanation could be specific, training-related differences among the 3 groups in evaluation of forelimb lameness localized to the shoulder. However, all 3 groups cited similar orthopedic examination criteria, with changes to shoulder abduction angle as the primary physical examination finding and discomfort during shoulder manipulation as the second most common finding. Historically, shoulder abduction angles were reported to be helpful in the diagnosis of MSS/MSI, with normal shoulder abduction angle reported to be ~30° and shoulder instability in dogs with a shoulder abduction angle > 50° (7). More recently, the accuracy and repeatability of shoulder abduction angles have been called into question (13,14). In a cadaveric study, when compared to fluoroscopy, observer-measured shoulder abduction and repeatability between observers were both poor (14). Furthermore, in a study on ultra-endurance Alaskan sled dogs with normal joints, average shoulder abduction angle ranged from 43.8 to 48.2°, and some dogs had shoulder abduction angles as high as 75° (3,13,31). It is concerning that the currently available literature does not support the use of shoulder abduction angles, yet this was the most common diagnostic modality that respondents relied on, regardless of specialty. Furthermore, although respondents relied on shoulder abduction angle for diagnosis, they questioned its reliability. This implies that more research is needed on the use of shoulder abduction angles, including whether there are breed differences. In the authors’ opinion, research should evaluate various functions of working and sporting dogs and their roles in shoulder abduction, to differentiate “normal wear and tear” of the shoulder from development of a pathological problem.

Diagnostically, ACVSMR diplomates relied more on ultrasonography than did ACVS/ECVS and double-Boarded diplomates, partially supporting our second hypothesis. The use of MSK US has been reported for MSS/MSI (8,9) and, in the authors’ opinion, is gaining popularity within the sports medicine and rehabilitation community. Hence, it was not unexpected that ACVSMR diplomates used MSK US more frequently. Even though the ACVSMR diplomates used MSK US more often, a perceived consensus between groups on preferred diagnostic imaging was not identified. In addition, confidence in an accurate diagnosis with the current imaging options was lower among double-Boarded diplomates compared to ACVS/ECVS or ACVSMR diplomates. This finding is difficult to explain, as double-Boarded diplomates would belong to both ACVS/ECVS and ACVSMR. However, double-Boarded diplomates may have more experience within each specialty in dealing with various diagnostic modalities, allowing an opinion to be formed.

There was a perceived consensus regarding the underlying cause for MSS/MSI and the first line of treatment. The majority of ACVS/ECVS and ACVSMR diplomates felt that MSS/MSI is most likely secondary to repetitive trauma, resulting in a chronic rather than an acute condition. Most ACVS/ECVS and ACVSMR diplomates recognized rehabilitation alone as the first-line treatment for suspected cases of MSS/MSI. Few ACVSMR and no ACVS/ECVS diplomates felt orthobiologics were warranted for treatment of this condition.

Regarding surgical intervention, most respondents recommended some form of prosthetic ligament reconstruction through an open approach, with the majority feeling that current techniques are technically challenging to complete. Prosthetic reconstruction is a broad term, and the survey did not specifically ask what type of reconstruction was being done. The data indicated that ACVSMR respondents would be 4.5× more likely to recommend RITC as a surgical option compared to ligament reconstruction, whereas ACVS/ECVS or double-Boarded diplomates would recommend ligament reconstruction compared to RITC, supporting our third hypothesis. With that treatment preference, ACVSMR diplomates were also more likely to recommend arthroscopic treatment as the primary aspect of surgical intervention versus ACVS/ECVS or double-Boarded diplomates. The finding that ACVS/ECVS diplomates would recommend prosthetic ligament reconstruction was expected. However, that ACVSMR diplomates were more likely to recommend RITC was not expected. It would be interesting to know the origin of this discrepancy between specialties. Franklin et al reported that outcomes of dogs undergoing RITC were not different from outcomes of dogs treated conservatively (4). The finding in this survey could have been due to differences in approach between specialties. Perhaps ACVSMR diplomates focus more on nonsurgical management strategies and perceive RITC as less invasive.

Perceptions of surgical techniques also supported our third hypothesis. ACVSMR diplomates reported available surgical techniques as mostly unachievable and that they tried to avoid surgery (P < 0.001). This was attributed to ACVSMR diplomates not primarily performing surgery and perhaps lacking familiarity with the surgical techniques. The recommendation for RITC over prosthetic ligament reconstruction by ACVSMR diplomates further supported this rationale, as it is a less technically demanding procedure. The ACVS/ECVS diplomates reported surgical techniques as complex and difficult to complete, albeit effective when prosthetic ligament reconstruction has occurred.

This study had limitations. Although the survey was distributed across 2 email listservs and 1 database, only 1 means of contact was inclusive of an entire college (ACVSMR), whereas the Colorado State University orthopedic listserv and the Veterinary Arthrology Association listserv were voluntary. Unfortunately, the database of ACVS/ECVS diplomates was not readily available to the authors, despite 2 of the 4 authors having diplomate status. This discrepancy may have underrepresented diplomates of ACVS/ECVS. In addition, the study was only administered in English, which may have discouraged participation from individuals whose primary language was not English.

As the total number of respondents was limited (15.8% known response rate), results should be interpreted with caution. However, the survey completion rate was comparable to that for a published study in the veterinary literature (32). The survey was designed to reach many veterinarians to provide evidence of the current attitudes and recommendations on the frequency of and diagnostic and treatment options for MSS/MSI. The lower response rate could have been secondary to bias for responses from only those with interest or experience in MSS/MSI. As with any survey-based study, survey results may have been influenced by the questionnaire format. Specifically, there were only 11 questions with 4 or 5 answer options, which may not have fully represented respondents’ opinions on the subject matter. Some questions had an “other” option where participants could type in specific answers, whereas other questions asked for a “preferred method” but allowed respondents to select multiple options. This could have complicated determining which method was truly preferred. However, our goal was not to rank methods but to simply discover which methods are commonly used, as some individuals may have equally preferred methods. A statistician was engaged for the statistical analysis, but no statistician was involved in the planning process. Ideally, a statistician should be consulted in the planning phase to ensure questions are written to obtain data with the greatest clinical relevance. We attempted to ensure questions were designed to obtain relevant data by sending the questionnaire to a select group of diplomates for review and critique before finalizing the questionnaire, but this was a shortcoming of the study design.

The term “known response rate” is used throughout this article. Since we used email listservs rather than an individual list of emails, it was not possible to know the true population sample size. Some emails could have been duplicates; i.e., if a respondent was a member of > 1 email listserv. In addition, it is possible that a single respondent had > 1 email address or that inactive email addresses were included in the overall email list, which would have skewed our overall sample size. In some cases, the survey email may have gone to a junk email folder and the intended recipient never received it. However, these potential errors would likely falsely lower the response rate rather than falsely increase it.

In conclusion, although this study had limitations, the results supported a perceived agreement on the underlying cause of MSS/MSI as well as the initial treatment recommendations. There were differences in the perceived frequency of MSS/MSI across specialties. In addition, there was a lack of perceived consensus on the diagnostic assessment of and surgical treatment recommendations for canine MSS/MSI between diplomates from ACVS/ECVS and ACVSMR. Based on this survey, evidence-based consensus guidelines for evaluation and treatment of MSS/MSI appear warranted. Guidelines are particularly important as training requirements between the 2 colleges are vastly different. Continuing differences between specialties regarding how to diagnose and treat MSS/MSI will create confusion and uncertainty, not only for pet owners, but also for veterinarians who may not see these cases frequently. To further aid in the development of consensus guidelines, multicentered research efforts are necessary, examining in particular diagnostic modalities, various treatment recommendations, and when to recommend conservative therapy versus surgical therapy.