# Reproductive Control in Dogs with Emphasis on Anti-GnRH Immunocastration and Its Behavioral Effects

## TL;DR

Immunocastration, a vaccine targeting GnRH, offers a humane and scalable alternative to surgical castration for controlling dog overpopulation and reducing unwanted behaviors.

## Contribution

This review evaluates the behavioral and physiological effects of anti-GnRH immunocastration in dogs and its potential for large-scale population control.

## Key findings

- Immunocastration reduces reproductive hormones and unwanted behaviors like roaming and aggression in dogs.
- The method shows fewer negative emotional side effects compared to surgical sterilization.
- It is a cost-effective and reversible option suitable for mass implementation in resource-limited areas.

## Abstract

Dog overpopulation is a global issue affecting public health, the environment, and animal welfare. Many free-roaming dogs live in cities, contributing to the spread of diseases, traffic accidents, and environmental contamination. Traditional control methods, like surgical castration or euthanasia, can be costly, invasive, or socially unacceptable. Immunocastration—a type of vaccination that prevents reproduction by targeting reproductive hormones—offers a promising, more humane alternative. This approach avoids surgery, reduces unwanted behaviors like aggression or roaming, and can be applied on a large scale. This review explores how immunocastration works, its effects on dogs’ behavior and health, and how it compares to traditional sterilization. It also reviews evidence from other species, including pigs, cattle, and horses, where immunocastration has been used successfully. The findings show that this method can help reduce dog overpopulation more ethically and sustainably, especially in areas with limited veterinary resources. By better understanding the benefits and limitations of immunocastration, veterinarians and policymakers can make more informed decisions to promote animal and public health.

Dog overpopulation poses serious challenges to public health, animal welfare, and environmental sustainability. While surgical castration remains the most commonly used method for controlling reproduction in dogs, it carries risks and limitations, including surgical complications and long-term behavioral or physiological side effects. This review examines the potential of immunocastration—vaccination targeting gonadotropin-releasing hormone (GnRH)—as an alternative approach. Immunocastration has been shown to suppress reproductive hormones, reduce gonadal function, and decrease behaviors such as roaming, aggression, and sexual mounting in dogs. The review also includes evidence from other species (e.g., pigs, cattle, and horses) to contextualize effectiveness and welfare implications. While behavioral effects are more variable and less frequently studied than physiological outcomes, recent findings suggest immunocastration may have fewer negative emotional side effects (e.g., anxiety and stress-related behaviors) than surgical sterilization. The review highlights the mechanisms, applications, and behavioral outcomes of immunocastration, including its reversibility, cost-effectiveness, and suitability for mass implementation. Overall, immunocastration offers a promising addition to dog population management strategies, particularly in regions with limited surgical infrastructure. Future research should focus on standardizing vaccine protocols and assessing long-term behavioral and welfare outcomes in diverse dog populations.