Examination of the use of intraovarian administration of CaCl2 and zinc gluconate as potential chemosterilants in Bos indicus heifers

Calcium chloride diluted in ethanol 95% as female sterilizing agent: effect of transcutaneous delivery in rats

Background

Different fertility control methods are investigated as a tool for population control of free-roaming animals. Chemical castration using calcium chloride has been widely studied over the years in males, but there are few studies related to its use in females. Therefore, we aimed to evaluate the local effects, as a potential chemosterilant, of two concentrations of calcium chloride diluted in 95% ethanol when administered by transcutaneous ultrasound-guided intraovarian injection in rats. In this study, 30 female Wistar rats were randomly divided into three treatment groups, which consisted of transcutaneous ultrasound-guided intraovarian injection of: 0.9% sodium chloride solution (GC); 10% calcium chloride diluted in 95% ethanol (G10); 20% calcium chloride diluted in 95% ethanol (G20). The animals were subdivided into two evaluation times, 15 days (n = 5 of each group) and 30 days (n = 5 of each group) after the intraovarian injection. The ovarian diameter was measured using ultrasound image prior and immediately after the injection and after the treatment period. Furthermore, animals’ clinical evaluation, estrous cycles assessment, macroscopic examination of the abdominal cavity and histological evaluation of the ovaries were performed.

Results

Ovarian ultrasound measurement revealed changes (p < 0.05) between ovarian diameters before and immediately after the injection in all treatments. Three animals in G20 had a small focal skin lesion at the injection site that evolved to total healing. Extended and abnormal estrous cycles were observed in G10 and G20. At gross examination, adhesions and ovarian cysts were noticed in both groups, G10 and G20. Also, the histopathology analysis revealed changes in ovarian architecture and vessel congestion in G10 and G20, but ovarian tissue damage was greater in the ovaries treated with the highest concentration (G20).

Conclusions

The results indicate that 20% calcium chloride diluted in 95% ethanol may be a potential agent for inducing sterilization in females and was possible to be minimally invasively delivered.

Transcutaneous Ultrasound Guided Intraovarian Injection in Rats (Rattus norvegicus)

The goal of this study was to develop a method for ultrasound-guided percutaneous intraovarian injection in Wistar rats.Intraovarian administration of chemicals or needle aspiration of the ovary has been undertaken in some species, includinghumans, equines, and bovines. In rodents, which are widely used in scientific research, a technique for intraovarian injectionwithout surgical exposure of the organ has not been described. The current study standardized the procedure of ovarianpercutaneous injection of 0.9% sodium chloride guided by ultrasound in rats. The ovaries were measured by ultrasoundimaging before and immediately after injection and showed a significant increase in ovarian length but not width. No clinical abnormalities were detected within 15 d after injection. These findings indicate that the steps of ultrasound localization of the organ, digital restraint, and correct needle insertion achieved successful intraovarian administration of saline without invasive surgery. These results document the feasibility of ultrasound-guided intraovarian percutaneous injection in rats and may be useful for future research on female reproduction and chemical sterilization.