Effects of Human Chorionic Gonadotrophin (HCG) on Dog Semen Quality

Objectives - It has been reported that single injections of human chorionic gonadotrophin (HCG) can lead to a transient improvement of the quality of canine semen [1,2]. The goal of the present study was to check the effect of repeated injections of the hormone for a longer period.

Materials and methods - Initial studies included 10 dogs (7 Beagles and 3 mixed breed, 3 to 11 years old) belonging to the kennels of the School of Veterinary Sciences. After 6 weeks of sperm controls to establish the baseline seminal quality of each dog, animals were divided into 2 groups of similar age and seminal quality distribution. Group 1 received hormonal treatment during 9 weeks, while group 2 remained untreated and constituted the control group. Sperm analyses were performed on a weekly basis until week 20 from treatment onset. From that time point, group 2 received hormonal treatment during 9 weeks while group 1 remained untreated and served as control. Treatment consisted in subcutaneous injections of 500 IU of HCG once a week. Data recorded from sperm analysis included total sperm count in the ejaculate, % of abnormal forms and % of progressive motility.

Results - The sperm count in the ejaculate was highly variable both within the same individual and between different animals. Notwithstanding, each dog evidenced an improvement in the total sperm count which started at week 4 of hormonal treatment, reached a maximum at week 8 and persisted at this level for at least 9 further weeks (Figure 1). No significant changes were observed in the % of abnormal sperm cells in the ejaculate or in the % of progressive motility, in contrast with previous studies by Kawakami et al. [2]. The same hormonal treatment was later used in 8 clinical cases of dogs with infertility (n = 5) or subfertility (n = 3). Sperm analysis showed oligospermia with high percentage of abnormal forms in 2 cases, and low percentage of progressive motility in 2 dogs. At the time of writing this report, animals have been under hormonal treatment for 12 months. Fertility recovery, which persisted during the whole treatment, was observed in 6 cases. No response was obtained in another dog, and the remaining one exhibited a slight improvement of semen quality but did not recover fertility. The hormonal treatment was also used in 5 azoospermic dogs in which it did not produce any beneficial effect, in agreement with a previous study by Kawakami et al [1].
These results suggest that treatment with serial injections of HCG can improve the quality of canine semen and the fertility of oligospermic dogs.