Summary
To evaluate a novel tendon biopsy technique for use in the horse and to assess the
effect of different exercise levels on the healing process of minimally damaged superficial
digital flexor tendons (SDFT), 24 Dutch Warmblood foals were randomly divided into
3 equally sized groups one week after birth. One group was box rested, one group got
box rest with additional enforced exercise, and one group got free pasture exercise.
Biopsies from the peripheral region of the SDFT were taken at age 2 months using a
new micro-biopsy technique. At age 5 months the foals were euthanized and samples
from the biopsy site and a control site were harvested. Collagen fibrillar index (CFI,
the total amount of collagen as a percentage of the measured area), mass-average diameter
(MAvD, mean of the diameter versus area distribution) and collagen fibrillar diameter
frequency (the distribution of collagen fibril sizes expressed as a percentage of
the number of collagen fibrils) were calculated. The CFI, MAvD values were significantly
lower in the wound samples. It is concluded that the biopsy technique may be a useful
tool for research applications. The absence of exercise-induced effects on the collagen
fibril population in the wound samples suggests that the first phase of the process
of tendon healing in immature equine SDFT’s sustaining a minor surgically-induced
wound, is not exercise-dependent. However, findings may be different in mature horses
sustaining accidental trauma.
A novel technique to take biopsies from immature equine flexor tendons was developed
and used to evaluate the effect of various levels of exercise on the development of
the collagen fibril diameter distribution in the resulting wounds. The technique appeared
to be minimally invasive, but complication rate was deemed too high for clinical use.
There was no effect of exercise on mass average diameter of collagen fibrils, suggesting
that the repair process, at least in its initial stage, is exercise-independent.
Keywords
Foal - SDFT - collagen fibril population - tendon healing - biopsy
