An immunologic approach to population control in dogs.

Area of Science:

• Immunology
• Reproductive Biology
• Endocrinology

Background:

• Luteinizing hormone (LH) plays a critical role in male reproductive functions, including testosterone production and spermatogenesis.
• Investigating the effects of targeted immune responses against endogenous hormones is crucial for understanding reproductive physiology and potential contraceptive strategies.

Purpose of the Study:

• To evaluate the impact of immunization against bovine luteinizing hormone (bLH) on testicular, thyroidal, and adrenal functions in male Beagles.
• To assess the correlation between circulating antibodies against bLH and reproductive dysfunction.
• To determine the cross-reactivity and efficacy of heterologous gonadotropins in immunized dogs.

Main Methods:

• Male Beagles were immunized with bovine luteinizing hormone for 15 or 52 weeks.
• Testicular, thyroidal, and adrenal activities were measured.
• Circulating antibody levels and reproductive parameters were assessed.
• Responses to single doses of human chorionic gonadotropin (hCG) and ovine gonadotropin were evaluated.

Main Results:

• Antibodies against bLH were associated with significant atrophy of the testes, epididymides, and prostate gland.
• Reproductive dysfunction, including inability to ejaculate, persisted for up to a year in 75% of immunized dogs.
• Thyroid and adrenal gland functions were not detectably affected by the immunization.
• hCG antibodies did not cross-react with canine gonadotropins and did not induce reproductive failure.
• Ovine gonadotropin stimulated antibody production linked to impaired ejaculation.

Conclusions:

• Active immunization against luteinizing hormone can lead to testicular atrophy and reproductive failure in male dogs.
• The immune response is specific to LH and does not significantly impact thyroid or adrenal function.
• Heterologous gonadotropins may elicit varied immune responses with differing reproductive consequences.