16/04/2026
Soundness and healing are not the same thing.
This is the mistake that re-injures more horses than any other.
The horse feels better. Moving well. You can see it. So the workload increases.
And weeks later, the tendon is worse than at initial injury.
Here's what's actually happening:
After one to two weeks, a reduction or absence of lameness will be seen alongside resolution of the signs of inflammation - but the tendon will remain palpably enlarged and soft.
Pain resolves because acute inflammation settles. Nerve fibres calm down. The horse stops protecting the limb.
But the lesion is still there.
During the proliferative phase, the tendon creates a "provisional matrix" using Type III collagen, which is stiffer than Type I. While this provides a useful scaffold for reconstruction, it lacks the sophistication of the original tendon composition.
In plain terms: the repair tissue is immature, disorganised, and mechanically inferior to what it replaced. It cannot tolerate the load you're asking it to carry.
Abnormal high levels of Type III collagen and an absence of any rectilinear assembly may be present up to fourteen months after injury.
Fourteen months.
Healing takes place through three overlapping phases - initial inflammation, subsequent fibroplasia, and then a long and incomplete process of remodelling of the scar tissue. The remodelling phase is where most horses are destroyed by good intentions.
Soundness doesn't necessarily correlate with a healthy tendon - that's a direct quote from the research, not an opinion.
The only way to know when tissue is ready is imaging. Serial ultrasound - monitoring cross-sectional area, echogenicity, and fibre alignment - at every exercise transition, every three months.
Not feel. Not movement assessment.
Not "he seems fine."
Imaging.
"Feels better" is not a timeline.
It's a trap.
Sources:
Smith RKW, Equine Veterinary Education 2024;
O'Brien et al. via The Horse 2023; Stem cell & collagen III research via PetHelpful/Vettimes
