The Thoroughbred racing industry faces a persistent decline in racing populations not solely due to fewer foals being bred, but primarily because a significant portion of horses fail to remain physically viable for racing careers. Approximately 29% of registered foals never start a race, often exiting quietly during training due to soundness issues, physical limitations, or inability to tolerate conditioning. Musculoskeletal injuries, chronic bone remodeling abnormalities, respiratory diseases, and systemic inflammation contribute heavily to early attrition, with many horses developing cumulative microdamage and chronic conditions that reduce durability before catastrophic injuries occur.

Despite advances in diagnostic technology, the industry’s medical approach remains largely reactive, focusing on detecting injuries after they happen rather than preventing them. This reactive model overlooks the complex interactions of environment, respiratory health, and inflammation that erode a horse’s resilience over time. Without a shift toward preventive health strategies emphasizing adaptation and durability, efforts to increase foal crops or adjust racing conditions will fail to reverse declining field sizes. Ultimately, the population crisis hinges on maintaining horses’ biological resilience to sustain longer, healthier racing careers rather than simply increasing breeding numbers.