Recombinant equine growth hormone does not affect the in vitro biomechanical properties of equine superficial digital flexor tendon.

OBJECTIVE

To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of normal adult equine superficial digital flexor tendon (SDFT).

STUDY DESIGN

Completely randomized design.

SAMPLE POPULATION

Nine Standardbred horses, 6 to 9 years of age with ultrasonographically normal forelimb SDFT.

METHODS

Six horses were administered intramuscular (IM) rEGH at 10 microg/kg/day for 1 week, and then 20 microg/kg/day for another 5 weeks; 3 horses (control subjects) were administered an equivalent daily volume of sterile water IM. Horses were killed at the end of the 6-week treatment period, and both forelimb SDFT were harvested and stored at -70 degrees C. In vitro biomechanical testing was performed under uniaxial tension. Results were analyzed using a general linear model of analysis of variance; significance was set at P <.05.

RESULTS

There were no differences in cross-sectional area, maximal load at failure, yield load, ultimate and yield tensile strain, ultimate and yield tensile stress, or stiffness between tendons from control and treated horses.

CONCLUSIONS

Administration of rEGH to adult Standardbred horses for 6 weeks had no detectable effect on the in vitro biomechanical properties of normal SDFT.

CLINICAL RELEVANCE

Administration of rEGH does not modulate the in vitro biomechanical properties of SDFT from adult Standardbred horses.