Radiographic findings of candidate stallions presented for licensing at all German Warmblood horse-breeding associations in 2018-2020.

Overview

• This study examined radiographic findings in German Warmblood stallions presented for licensing between 2018 and 2020 to assess how frequently abnormalities appear and what environmental factors might influence these findings.
• The research identified common patterns in radiographic results and highlighted variability among evaluators, suggesting the need for follow-up assessments to determine the clinical significance of these findings.

Study Background and Purpose

• Warmblood stallions undergo licensing to ensure suitability for breeding, with health assessments including radiographic examinations to detect bone and joint abnormalities.
• Prior to this study, there was limited information on the health status, particularly radiographic conditions, of young German Warmblood stallions.
• The primary objective was to evaluate the prevalence of radiographic abnormalities noted during licensing and to examine whether external factors like birth season, age, or evaluator influenced these findings.

Methods

• The study was retrospective and observational, analyzing records from 1678 stallions, accounting for 1693 radiographic examinations over a three-year period (2018-2020).
• Data were sourced from all German Warmblood breeding associations and their official veterinarians, ensuring comprehensive coverage.
• Records were stored and managed using the German equine health database for standardized data handling.
• Only the latest radiographic examination per horse was considered in the analysis to maintain data relevance and avoid duplication.
• Statistical analysis involved generalized linear models to test the influence of factors such as:
  • The season of birth
  • Age at licensing
  • Year of licensing
  • Evaluator performing the assessment

  with significance set at p < 0.05.

Key Findings

• High prevalence of radiographic remarks: 71.4% of candidate stallions had noted findings in their radiographs.
• Despite the high percentage with findings, most horses had either one (49.8%) or two (34.4%) abnormalities, indicating multiple severe issues were less common.
• Main anatomical regions with findings:
  • Proximal phalanx including the metacarpo-/metatarsophalangeal joint (25.3%)
  • Third metacarpal/metatarsal bone (20.3%)
  • Navicular bone (17.2%)
  • Tarsus (ankle joint) (17.2%)
• Types of radiographic abnormalities included:
  • Osseous fragments in the metacarpo-/metatarsophalangeal joint
  • Contour changes in the proximal phalanx and third metacarpal/metatarsal bones
  • Changes in navicular synovial invaginations
• Environmental and temporal factors such as season of birth, age at licensing, and year of licensing showed no significant effect on most radiographic findings, indicating these factors likely do not influence bone/joint abnormalities detected at licensing.
• However, the evaluator (the veterinarian assessing the radiographs) significantly influenced the distribution of findings, suggesting possible subjective variation or differences in diagnostic criteria among evaluators.

Conclusions and Implications

• Many German Warmblood stallions presented for licensing exhibited radiographic abnormalities, though many had few such findings.
• The clinical relevance (i.e., impact on health, performance, or breeding suitability) of numerous radiographic abnormalities in these apparently healthy stallions remains unclear.
• Significant evaluator variability highlights the need for standardized evaluation protocols or training to improve consistency.
• The study recommends follow-up assessments and longitudinal studies using the collected data to better understand the risk these radiographic findings pose and to possibly develop improved health assessments for breeding stallions.