Effects of intratesticular administration of zinc gluconate and dimethyl sulfoxide on clinical, endocrinological, and reproductive parameters in dogs

Male animal sterilization: history, current practices, and potential methods for replacing castration

Sterilization and castration have been synonyms for thousands of years. Making an animal sterile meant to render them incapable of producing offspring. Castration or the physical removal of the testes was discovered to be the most simple but reliable method for managing reproduction and sexual behavior in the male. Today, there continues to be global utilization of castration in domestic animals. More than six hundred million pigs are castrated every year, and surgical removal of testes in dogs and cats is a routine practice in veterinary medicine. However, modern biological research has extended the meaning of sterilization to include methods that spare testis removal and involve a variety of options, from chemical castration and immunocastration to various methods of vasectomy. This review begins with the history of sterilization, showing a direct link between its practice in man and animals. Then, it traces the evolution of concepts for inducing sterility, where research has overlapped with basic studies of reproductive hormones and the discovery of testicular toxicants, some of which serve as sterilizing agents in rodent pests. Finally, the most recent efforts to use the immune system and gene editing to block hormonal stimulation of testis function are discussed. As we respond to the crisis of animal overpopulation and strive for better animal welfare, these novel methods provide optimism for replacing surgical castration in some species.

Ageing changes testes and epididymis blood flow without altering biometry and echodensity in dogs

Senescence leads to deleterious effects in testicular function, sperm quality and fertility in dogs. There, however, are no consistent results of vascular changes in the testes and epididymis during natural ageing in dogs. The aim of this study, therefore, was to compare testes and epididymis blood flow, biometry and echodensity between young and senile dogs. Ten young dogs (1-4 years) and eight senile dogs (over 7 years) were selected and assigned to two experimental groups: Young Group and Senile Group. Dogs were evaluated using testicular and epididymis B-mode (dimensions and echodensity) and Doppler ultrasonography (tissue perfusion parameters and blood flow velocity of the testicular artery). There were no differences between experimental groups for the echographic evaluation of testicular and epididymis parenchyma and biometric variables. The dogs in the Young Group had greater (P = 0.02) testes vascularization score and greater (P = 0.06) testicular artery blood flow velocity than those in the Senile Group. Furthermore, the older dogs had a greater (P = 0.06) pulsatility index of the testicular artery than those in the Young Group. Ageing, therefore, seems to cause natural hemodynamical changes to the testicular artery, resulting in reduced blood flow (ischemia) and tissue damage. Testes and epididymis vascular characteristics, therefore, may represent the causal factors for changes in spermatogenesis and, as a consequence, negatively affect the sperm quality of older dogs. In conclusion, senescence alters testicular artery blood flow and vascularization of the testes, without changing testicular and epididymis ultrasonographic dimensions and echodensity in dogs.

Reproductive and endocrinological effects of Benign Prostatic Hyperplasia and finasteride therapy in dogs

Benign prostatic hyperplasia (BPH) is one of the most important reproductive disorders in aging dogs. Therapeutic measures include orchiectomy and pharmacological treatment, leading to reduction of prostate volume and clinical signs. One of the most common drugs used in BPH treatment is finasteride, but data regarding its possible side effects are scarce. Thus, the aim of this study was to evaluate the effects of BPH and short-term (2 months) finasteride therapy on clinical, endocrinological, and reproductive parameters in dogs. Dogs were allocated into four experimental groups: Non-affected (n = 5), BPH (n = 5), Non-Affected-Finasteride (n = 5) and BPH-Finasteride (n = 5) groups. Dogs were evaluated monthly during 2 months by a complete breeding soundness examination, B-mode ultrasound and Doppler ultrasonography of the testicular artery, hormonal profile (testosterone, estrogen and dihydrotestosterone) and oxidative profile of the prostatic fluid. After 2 months, dogs were gonadectomized and testicles were subjected to histologic analysis. Finasteride treatment reduced dihydrotestosterone concentrations, without negative influence on semen quality and also reverted testicular hemodynamics changes of BPH. On the other hand, BPH was accompanied by significant changes in testosterone and estrogen concentrations and semen quality, mainly related to sperm kinetics alterations. In conclusion, BPH dogs have important hormonal and sperm alterations, however, short-term finasteride treatment (2 months) was able to reduce overall effects of BPH, thus representing a method of therapy for BPH treatment.

Acute reproductive toxicology after intratesticular injection of silver nanoparticles (AgNPs) in Wistar rats

This study aimed to evaluate the effects of an intratesticular injection of silver nanoparticles (AgNPs) on reproductive parameters and health of rats, and to evaluate the AgNPs biodistribution in order to develop a nanotechnological contraceptive agent for male animals. Treated animals received 220 μL of AgNPs solution (0.46 µg-Ag/ml) in each testicle and were euthanized: seven, 14, 28, and 56 days after injection. A significant decrease (p < 0.05) in the percentage of motile sperm in D7 (8.8%) was observed, comparing to the control (73.3%), D14 (86.0%), D28 (68.2%), and D56 (90.0%) groups. D7 group also presented a decrease (p < 0.05) in the percentage of normal spermatozoa. Additionally, D7 group showed an increase (p < 0.05) in abnormal midpiece and sperm head morphology compared to the Control group. Seminiferous tubules presented all germline cell types and spermatozoa for all groups. However, D7 group did not present spermatozoa in the epididymis, whereas some spermatozoa and cellular debris were visible in D14 and D28 groups. All animals presented hematological parameters, creatinine, and alanine aminotransferase values within the normal limits for Wistar rats. The percentage of silver found in the liver was always higher than in the other organs analyzed. A pioneering mathematical model is proposed, from which the half-life time of silver in the liver (17 days), spleen (23 days), lungs (30 days), and kidneys (35 days) was extracted. In conclusion, some acute and severe toxic effects were observed in sperm cells following intratesticular injection of AgNPs, although these effects were reversible. No adverse effects to general animal health were observed.

Chemical sterilization with intratesticular administration of zinc gluconate in adult dogs: a preliminary report

BACKGROUND

Chemical sterilization with zinc gluconate is being developed due to its permanent contraceptive effect in prepubertal dogs. In this study, five healthy adult dogs were selected randomly. Semen samples were collected and analyzed before the study to confirm normal testicular function. Under general anesthesia, pH neutralized zinc gluconate was injected directly into their testes. Testes diameter, ultrasonographic appearance, changes in the percentage of white blood cells, and testosterone concentration were monitored twice a week before and 1 month after the injection. At the end of the study, the dogs were castrated and their testes were removed for histopathological evaluation.

RESULTS

The general health of all dogs was normal after the injection. The appearance of testicular swelling was limited within 2 days of treatment. The average diameter of left and right testes was 2.48 and 2.03 cm before the injection and reached to diameter 2.12 and 2.15 cm, respectively, at the end of the study. Serum testosterone concentration was 4.2 ng/ml at the start and 4 ng/ml at the end of the study. The percentage of white blood cells at the start and end of the study were within normal ranges reported for dogs. Histopathological analyses indicate a degeneration of germ cells in seminiferous tubules, but Leydig cells retained their structure.

CONCLUSIONS

Therefore, It is inferred that the injection of pH neutralized zinc gluconate into the adult dogs' testes resulted in the loss of sperm-producing tissue without affecting the production of testosterone and the general health of adult dogs.

Effects of chemical castration using 20% CaCl2 with 0.5% DMSO in tomcats: Evaluation of inflammatory reaction by infrared thermography and effectiveness of treatment

This study used infrared thermography to monitor the immediate inflammatory reaction to an intratesticular injection of 20% (calcium chloride) CaCl₂ with 0.5% dimethyl sulfoxide (DMSO) for chemical castration and to provide evidence of the treatment's clinical viability. Six animals received a 0.25 mL intratesticular injection of 20% CaCl₂ with 0.5% DMSO in each testis. Thermographic imaging, testicular measurement, penile spine evaluation, electroejaculation, and sperm analysis were performed before the injection. Eighty days post-injection, the cats were evaluated again, then received an orchiectomy followed by histological analysis. Infrared thermography of the testicular area was performed before (M0) and after anesthesia (M0A); after electroejaculation (M0E); 10 min (M1), 1 h, (M2) and 6 h (M3) after the injection for seven consecutive days (M4-10); after 15 (M11) and 30 days (M12); and after 80 days, before and after anesthesia and after electroejaculation (M13, M13A and M13E). No cats had a significant increase in testicular temperature or behavioral changes. All animals were azoospermic and had a 50% reduction in total testicular volume after 80 days. Histologically, the testes showed different degrees of degeneration, necrosis, calcification and replaced connective tissue, as well as Leydig cell hyperplasia in 7/12 of the testes. Infrared thermography efficiently diagnosed and monitored scrotal inflammation caused by intratesticular injection of 20% CaCl₂ solution with 0.5% DMSO, and it is suggested that a single injection of this compound can cause azoospermia after 80 days. We concluded by infrared thermography with a clinical exam, that the adverse reactions were minimal and did not interfere with animal welfare.