Functional adaptation through changes in regional biochemical characteristics during maturation of equine superficial digital flexor tendons.
OBJECTIVE
To quantify and compare biochemical characteristics of the extracellular matrix (ECM) of specimens harvested from tensional and compressive regions of the superficial digital flexor tendon (SDFT) of horses in age classes that include neonates to mature horses.


METHODS
Tendon specimens were collected on postmortem examination from 40 juvenile horses (0, 5, 12, and 36 months old) without macroscopically visible signs of tendonitis.


METHODS
Central core specimens of the SDFT were obtained with a 4-mm-diameter biopsy punch from 2 loaded sites, the central part of the mid-metacarpal region and the central part of the mid-sesamoid region. Biochemical characteristics of the collagenous ECM content (ie, collagen, hydroxylysylpyridinoline crosslink, and pentosidine crosslink concentrations and percentage of degraded collagen) and noncollagenous ECM content (percentage of water and glycosaminoglycans, DNA, and hyaluronic acid concentrations) were measured.


RESULTS
The biochemical composition of equine SDFT was not homogeneous at birth with respect to DNA, glycosaminoglycans, and pentosidine concentrations. For most biochemical variables, the amounts present at birth were dissimilar to those found in mature horses. Fast and substantial changes in all components of the matrix occurred in the period of growth and development after birth.


CONCLUSIONS
Unlike cartilage, tendon tissue is not biochemically blank (ie, homogeneous) at birth. However, a process of functional adaptation occurs during maturation that changes the composition of equine SDFT from birth to maturity. Understanding of the maturation process of the juvenile equine SDFT may be useful in developing exercise programs that minimize tendon injuries later in life that result from overuse.
Lin
Yi-Lo
YL
Department of Equine Sciences, Faculty of Veterinary Medicine, Yalelaan 12, 3584 CM Utrecht, The Netherlands.
Brama
Pieter A J
PA
Kiers
Geesje H
GH
DeGroot
Jeroen
J
van Weeren
P René
PR
D000222:Adaptation, Physiological; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D003094:Collagen / Q000032:analysis; D005109:Extracellular Matrix / Q000737:chemistry*; D006736:Horses / Q000254:growth & development*; D008663:Metacarpus / Q000254:growth & development*; D013710:Tendons / Q000254:growth & development*
D003094:Collagen