# Clinical, Ovulatory and Histological Effect of a Postnatal Testosterone Treatment in Female Dogs

## TL;DR

This study examines how giving testosterone to newborn female dogs affects their reproductive development and found no major issues with ovulation or ovaries, but some uterine changes.

## Contribution

The study provides new insights into the effects of postnatal testosterone treatment on female canine reproduction.

## Key findings

- Testosterone-treated puppies had normal estrous behavior and ovulated without issues.
- Testosterone caused mild clitoris enlargement and increased uterine gland area and epithelium height.
- Ovarian structure and function remained unaffected by testosterone treatment.

## Abstract

Canine overpopulation is a major problem in many countries. It has been described in some female mammalian species that postnatal androgenization causes reproductive abnormalities. The objective of this study was to describe the reproductive effect of postnatal androgens in female dogs for contraceptive purposes. Ten newborn female puppies were administered testosterone (TE; n = 5) or placebo (PL; n = 5) subcutaneously. The puppies were followed up until puberty when ovulation was tested and then spayed. The genital tracts were grossly and microscopically examined. At puberty, all the females had normal estrous behavior and ovulated without age and body weight differences. All TE puppies presented mild clitoris enlargement. Ovaries did not reveal differences between groups. Conversely, the uterine glands as well as the height of the uterine epithelium were higher in TE. It was concluded that a postnatal dose of testosterone did not affect ovulatory capacity, nor did it cause gonadal alterations, although it caused an increased area of endometrial glands and a higher uterine epithelium.

It has been described in some female mammalian species that postnatal androgenization causes reproductive structural and functional abnormalities. The objective of this study was to describe the clinical, ovulatory and genital effects of postnatal androgens in female dogs. Ten newborn female crossbred puppies were randomly assigned to: testosterone enanthate 18 mg/100 g sc (TE; n = 5) or placebo sc (PL; n = 5). The puppies were physically followed up until puberty when ovulation was tested by serum progesterone. Then, ovariohysterectomies were performed, and genital tracts were grossly and histomorphometrically examined. At puberty, all the females had normal estrous behavior and ovulated without age and body weight differences. All TE puppies presented mild clitoris enlargement. Gross and microscopical ovarian examination did not reveal differences. Conversely, the endometrial area occupied by uterine glands as well as the height of the glandular and luminal epithelium were higher in the TE than in the PL group (<0.01). The height of the endometrium and myometrial thickness did not differ between groups. It was concluded that a supraphysiological postnatal dose of testosterone did not affect ovulatory capacity, nor did it provoke gonadal histological alterations, although it caused an increased area of endometrial glands and a higher uterine epithelium.