Background: Data on equine thoracic pathology hardly exist in other breeds than Thoroughbreds. Objectives: To describe pathological changes of the osseous thoracic vertebral column in Warmblood horses, Shetland ponies and Konik horses, and to compare prevalence and severity. Study design: Descriptive post-mortem study. Methods: Computed tomography examined the thoracic vertebral column of 34 Warmblood horses, 28 Shetland ponies, and 18 Konik horses. Osteoarthritis (OA), periarticular osteolysis (PO), cyst-like lesions (CLL) and fragments of articular processes (APJs), costovertebral (CVJs) and costotransverse (CTJs) joints, soft tissue (ST) mineralisation surrounding these joints, intervertebral disc (IVD) mineralisation, impingement of spinous processes (SPs) and spondylosis were scored. Results: APJ aplasia (98%; 58/ 59) occurred in 14 Shetland ponies. OA predominated in Warmblood horses across all joints (45% vs. 29 and 32%, p<0.001). OA and PO were particularly found in CTJs (p<0.001) across all breeds. Warmblood and Konik horses showed more and severe ST mineralisation than Shetland ponies (2.3%, score 1.5 and 3.2%, score 1.3, respectively, vs. 0.3%, score 0.9, p<0.01). Mid location was most often affected with highest severity score (4.2%, 1.5, p=0.001). Konik horses displayed the highest IVD mineralisation (20%, p<0.001), which notably increased with age (p<0.001) compared to Warmblood horses (4.5%) and Shetland ponies (1.1%). SPs impingement was absent in Shetland ponies, and most prevalent in Warmblood horses (11.2%, p=0.0004) compared to Konik horses (2.2%). CLL, fragments and spondylosis were minimal in all breeds, nearly absent in Shetland ponies. Main limitations: Clinical histories were unavailable. Conclusions: Distinct breed differences exist in prevalence and severity of thoracic vertebral column osseous pathologies. CTJ pathology prevails over APJ in all breeds. Warmblood horses are prone to OA, spondylosis and SPs impingement; Konik horses exhibit significant IVD mineralisation, and Shetland ponies demonstrate high APJ aplasia . PO, CLL, fragments and ST mineralisation are notably low in Shetland ponies.