Prevalence and radiographic features of cyst-like lesions in German Warmblood horses presented for pre-purchase examination.

Overview

• This study examined the prevalence, locations, and radiographic features of cyst-like lesions (CLLs) in sound German Warmblood horses undergoing pre-purchase examinations, aiming to improve understanding of their clinical significance and impact on purchasing decisions.

Introduction

• CLLs are frequently found on radiographs of equine limbs during pre-purchase examinations (PPEs).
• They may represent a risk factor in PPEs due to their potential to cause lameness or other clinical issues.
• Despite clinical concerns, some CLLs may be incidental findings without current clinical significance.
• This study specifically targeted sound German Warmblood horses to quantify the prevalence and characteristics of these lesions.

Study Design and Methods

• A retrospective cohort study was conducted, reviewing radiographs from 3863 German Warmblood horses presented sound for PPE at a German equine hospital over five years.
• Data collected included presence of CLLs, horse age, gender, and breeding area/studbook origin.
• CLLs identified on radiographs were independently evaluated by two observers using a newly developed comprehensive scoring system.
• The scoring system aimed to standardize evaluation of radiographic features of CLLs with both objective and subjective parameters.

Key Findings

• 176 cyst-like lesions were identified in 164 horses, resulting in a prevalence of 4.25% among the examined population.
• The median age of affected horses was 3.5 years, suggesting these lesions can be seen relatively early in life.
• Male horses comprised 67.68% of those with CLLs, possibly reflecting a selection bias because stallions are commonly presented for licensing exams.
• The majority of affected horses came from studbooks in Northwest Germany.
• CLLs were most commonly located on the proximal phalanx (32.96%) and medial/lateral femoral condyles (16.48%).
• The hindlimbs were more frequently affected (64.77%) compared to forelimbs.

Inter-Observer Agreement and Scoring System

• The novel scoring system showed a high level of inter-observer agreement, with kappa values ranging from moderate (κ = 0.5) to almost perfect (κ > 0.9) for different scoring parameters.
• Objective parameters (e.g., lesion size or location) reached excellent agreement.
• Subjective parameters (e.g., lesion appearance) showed lower agreement, highlighting challenges in consistent interpretation for these attributes.

Associations and Clinical Implications

• CLLs located abaxially in joints were significantly associated with concomitant osteoarthritic changes, suggesting these lesions may contribute to joint disease.
• The overall prevalence found aligns with outcomes reported in other literature, supporting the external validity of findings.
• The higher frequency in males may be influenced by the specific population examined, as stallions often undergo licensing PPEs more often.

Limitations

• The retrospective nature of the study may have caused underdiagnosis of lesions due to inconsistent radiographic protocols.
• Some PPE radiographs lacked caudocranial views of the stifle joint, likely leading to missed CLLs on the medial femoral condyle.
• The lack of clinical follow-up limits conclusions about the long-term significance of CLLs detected incidentally.

Conclusions

• CLLs occur in a small but notable proportion of clinically sound German Warmblood horses presented for PPE, with common locations in the proximal phalanx and femoral condyles.
• The newly introduced scoring system allows standardized and reproducible radiographic evaluation of these lesions.
• Findings emphasize the importance of thorough radiographic assessment using appropriate views to avoid underdiagnosis, particularly in pre-purchase contexts.
• Further research is needed to clarify the clinical relevance of incidental CLL findings and their impact on lameness and joint health over time.