Equine nuclear medicine: Current state of play

Equine nuclear medicine provides functional information on bone turnover, perfusion, inflammation and tracer biodistribution. Its role has evolved from planar scintigraphy toward SPECT, PET and quantitative imaging. This review synthesised the historical foundations and contemporary state of equine nuclear medicine, with emphasis on racehorse and performance-horse applications.

A PRISMA-aligned systematic narrative review and evidence map were undertaken. MEDLINE via PubMed, Web of Science Core Collection and SciQuest were searched, supplemented by reference-list screening, forward citation searching and snowballing. Eligible records addressed nuclear medicine imaging, radiopharmaceutical use, technical methods, diagnostic or therapeutic applications, dosimetry, radiation safety or facility/workflow considerations in horses. Heterogeneity in populations, indications, modalities and outcomes precluded meta-analysis; records were therefore mapped descriptively and synthesised narratively.

After consolidation and deduplication, 181 records were retained. Historical and foundational approaches accounted for 138 records, spanning non-skeletal applications, technical factors, musculoskeletal interpretation, lameness localisation and stress injury in performance / racehorses. This literature established scintigraphy as a tool for detecting altered skeletal turnover, localising occult or complex lameness and identifying stress remodelling or prodromal injury, while emphasising clinical correlation, normal-pattern recognition and technical standardisation. Contemporary approaches accounted for 43 records and included scintigraphic optimisation, quantitation, AI/radiomics, contemporary scintigraphy, SPECT and PET. These studies demonstrated refinement of planar scintigraphy, emerging standing SPECT for complex axial regions, and growth of standing 18F-NaF and 18F-FDG PET for distal-limb imaging, lesion monitoring and multimodality assessment.

Equine nuclear medicine has progressed from planar localisation toward a complementary functional imaging discipline. Scintigraphy remains useful for broad screening, SPECT is under-developed but promising for pelvis, vertebral column and head applications, and PET is the leading contemporary advance for high-resolution distal-limb imaging, quantitation and performance-horse injury prevention.