Background: For the last few years, researchers have been interested in developing a method for chemical
sterilization which may be a better alternative to surgical castration. An ideal chemical sterilant would be one that
effectively arrests spermatogenesis and androgenesis as well as libido with absence of toxic or other side effects.
Calcium chloride in various solutions and concentrations has been tested in many animal species, but few studies
have been evaluated it in equines as a chemical sterilant. So, the objective of this study was to evaluate the clinical
efficacy of chemical castration with 20 % calcium chloride dissolved in absolute ethanol in comparison with surgical
castration in donkeys based on the changes in the serum testosterone level and the histopathological changes in
treated testes.
Methods: Twelve clinically healthy adult male donkeys were used in this study. Donkeys were divided randomly
and equally into two groups: a surgical (S) group (n = 6) and a chemical (C) group (n = 6). Animals in the (S) group
were subjected to surgical castration while those in the (C) group received a single bilateral intratesticular injection
of 20 % calcium chloride dissolved in absolute ethanol (20 ml/testis). Animals were kept under clinical observation
for 60 days. Changes in animals' behavior and gross changes in external genitalia were monitored daily. Serum
concentrations of testosterone were measured prior to treatment and at 15, 30, 45 and 60 days post-treatment.
Testicles in the (C) group were examined histopathologically at the end of the experiment.
Results: Chemical castration with intratesticular calcium chloride vs. surgical castration failed to reduce serum
concentrations of testosterone throughout the whole duration of the study; however it induced orchitis that was
evident by focal necrotic areas in seminiferous tubules, cellular infiltration of neutrophils, proliferative intertubular
fibrosis with a compensatory proliferation of Leydig cells. Donkeys tolerated the intratesticular injection of calcium
chloride. There were no detectable changes in the general health status of the animals with the exception of
swelling in external genitalia, scrotal ulcerations and fistulas. Food and water consumption and the gait of animals
remained unaffected.
Conclusion: Intratesticular calcium chloride can’t be considered an effective method for chemical castration in
donkeys.