Immunocastration in donkeys: clinical and physiological aspects

Abstract

The work was aimed to evaluate testicular alterations induced by administration of immunocastration vaccine in Donkeys. A total of 12 adult Donkeys from the Northeast breed of Brazil were randomly distributed into control group (CG; n = 04) and immunocastration group (IG; n = 08). Donkeys from IG received two doses of Bopriva ® administered in an 30-day interval (Days 0 and 30). Blood samples were collected for testosterone dosage in this 30-day interval, when donkeys were weighted and measured for testicular biometry (testicular volume and tone). At the end of the experiment (Day 120), all donkeys were subjected to surgical castration in order to obtain testicular samples for histopathological analysis and from epididymis for evaluation of sperm cells. There was no difference in live weight (P > 0.05) within CG and IG groups during the experiment, however testosterone concentrations in IG donkeys were significantly (P < 0.05) lower after 30 and 60 days after the first vaccine, remaining in such levels until the end of the experiment. The CG did not show variations in testosterone levels during the experiment. No evidence of functional sperm cells was found in testis of IG donkeys, despite normal gametogenesis in CG. Testis from IG donkeys showed alterations in consistency and volume, suggesting a degenerative process, further confirmed by typical histopathological alterations of such pathology. Donkeys from the CG did not display these alterations. In IG donkeys, the ductal lumen of the epididymis ductal was dilated, filled with proteinaceous and eosinophilous content alongside with acidofilous germ cells. Furthermore, azoospermia was found in 75 % of IG donkeys, while remaining animals showed extremely low sperm concentration and no visible motility. Finally, immunocastration is an effective approach for male donkey castration due to its low cost and ease execution with no interference on animal welfare principles.

GnRH Vaccine could Suppress Serum Testosterone in Stallion Mules

“…However, the period of testosterone suppression in that study was more extended (5-6 months) than 16 weeks in this study. In stallion donkeys receiving the different brand of GnRH vaccine at 400 µg twice, serum testosterone decreased at day 60 after the first vaccination, and remained at a low level until the end of the study at day 120 [25], similar to the duration of testosterone suppression of stallion mules in this study. It was unknown whether the serum testosterone of stallion donkeys beyond 120 days would be maintained at a low level or rise in the similar pattern as mules in this study.…”

“…Mares receiving high dose of the GnRH vaccine (Improvac) at 400 µg had no injecting site swelling after primary vaccination but 10.9% developed visible swelling, and 3.6% developed visible swelling accompanied by lameness after the second vaccination [35]. Donkeys did not develop any clinical adverse effects even receiving high dose of the GnRH vaccine at 400 µg twice [25], although the brand of vaccine in that study was different from the one using in our study. Other composition of chemicals and adjuvants within different brands of vaccine might contribute to the occurrence of clinical adverse effects.…”

“…The GnRH vaccine has been evaluated for immunocastration in stallion horses [14,[21][22][23][24] and stallion donkeys [25]. To our knowledge, this study was the first to report information on GnRH vaccination in stallion mules.…”

Histomorphometric changes of testicular tissues by season and age of Algerian local donkeys (Equus asinus)

“…This is probably due to differences in the age and the larger size of the donkeys considered in the present study (140-250 vs. 400-450 kg). On the other hand, the mean value testis volume of donkeys obtained in this study is higher than that reported in the northeast Brazilian breed of donkeys (Rocha et al, 2018). The values of morphometric of the testicular parenchyma vary considerably among breeds, probably reflecting the spermatogenic activity for each breed.…”

Hematological and blood chemistry values of donkeys (Equus africanus asinus) in different management systems

“…The maintenance of donkeys in farms or breeding centers is not common around the world, as the majority of the population regularly rears these equids without much interest (Rocha et al 2018). This situation has made it difficult to characterize various blood biomarkers, which are important for the understanding of health and disease states of these animals.…”