The present study on sheep as an animal model was primarily conducted to induce
osteoporosis. As a side effect, it was an aim to show an alternative to conventional
ligature of the hilus of an excised ovary that is cheaper, easier and faster than the
The range of available animal models is large. The decision to use sheep as animal
model was because they have a similar hormone profile as compared to the human,
they are docile and easy to handle and the emotional binding between sheep and
humans is less intense than with some other species. Furthermore, ewes can be
housed in groups without suffering stress. In view of the side-effects of osteoporosis,
expected to occur as a result of ovariectomy, sheep models are also appropriate
because of the reasons mentioned before as
well as the size, what enables one to
establish prosthetic implantats, if orthopedic research is being performed.
The sheep were ovariectomized by the laparoscopic approach to reduce post-operative pain and surgical time.
Twenty-four healthy ewes, aged between
6 and 10 years were used. In 12 ewes,
ligation of the ovarian stump was done by
standard triple ligature with PGA (PGA, 2
USP, WDT, 30827 Garbsen). In the remaining 12 ewes, ligation was accomplished
by umbilical cord clamps.
After approximately 24 months, ewes were euthanized and necropsied to examine
the degree of adhesion formation.
Referring to the search for an alternative for standard triple ligature, the results were
quite interesting. Indeed it took less time
to use the umbilical cord clamps, it was
cheaper and easier to handle. In 5 out of 12 sheep, adhesions or loosened clamps were seen, but no signs of
inflammation or insufficient control of hemorrhage.
In conclusion, umbilical cord clamps are a useful and safe alternative to the standard
triple ligature and may thus be recommended.
Moreover, twenty months after the ovariectomy was conducted, measurement of
bone mineral density was performed by qCT. QCT is the most reliable technique to
obtain a reliable result.
Contrary to results of other studies, in the present project, sheep did not show signs
of bone loss as a consequence of the ovariectomy.