Postmortem characterization of cranial nuchal bursa and ligament in healthy horses reveals subclinical gross and histopathologic abnormalities.

Subclinical cranial nuchal bursitis with histopathologic changes is detectable in clinically normal horses, warranting further investigation.

This prospective descriptive cadaver study investigated the prevalence and histopathologic characteristics of subclinical cranial nuchal bursitis in 15 clinically normal horses from a Borrelia burgdorferi-endemic region. Horses with no history or clinical signs of cranial nuchal bursitis underwent postmortem evaluation of the cranial nuchal bursa, synovial fluid, and nuchal ligament. Gross abnormalities were identified in 4 of 15 horses (26.7%), including mineralization, bursal thickening, synovial effusion, amorphous material deposits, and adhesions. Histopathologic abnormalities were detected in 5 horses (33.3%), with findings including inflammation, edema, necrosis, fibrosis, and mineralization; overall histopathology scores ranged from 1 to 8 out of a possible maximum. Five horses demonstrated positive Lyme multiplex assay antibody titers; however, B. burgdorferi PCR on bursal tissue, nuchal ligament, and synovial fluid was uniformly negative, and 16S rRNA gene sequencing was performed on 3 samples. No statistically significant associations were identified between histopathology scores and age or Lyme multiplex titers. The study demonstrates that mild to moderate cranial nuchal bursa and ligament pathology can exist subclinically in apparently healthy horses, suggesting that clinical examination alone may underestimate the true prevalence of nuchal bursal disease. These findings highlight the need for further investigation into predisposing factors, etiopathogenesis, and the long-term clinical implications of subclinical nuchal bursitis in horses.

This summary was distilled by AI and may occasionally misinterpret data. Confirm critical details with the primary literature before clinical application.