A recent conversation at a dog club highlighted a common piece of advice given by veterinarians: neuter male puppies early to prevent aggressive or excitement-based behavior problems. This recommendation, however, is increasingly being questioned by new research. Two large studies have suggested that spaying and neutering might, in fact, lead to an increase in canine aggression. This has left many dog owners puzzled and seeking clearer guidance on what is best for their pets.
The core of this concern lies in a comprehensive study conducted by researchers at the Sydney School of Veterinary Science, University of Sydney. This extensive data collection involved nearly 10,000 dogs, with a specific focus on the behavioral effects of neutering in male dogs. The findings suggest a more nuanced relationship between neutering and behavior than is often presented. The study utilized the C-BARQ (Canine Behavioral Assessment and Research Questionnaire), a validated 100-item survey that gathers owner observations on various canine behaviors. The online accessibility of the C-BARQ since 2006 has allowed for a growing and increasingly precise database for canine behavior research. This wealth of data has enabled researchers to investigate the impact of neutering under various circumstances.
Understanding the Study’s Methodology
For this particular study, data was accepted from dogs that were neutered for reasons such as breeder or shelter requirements, birth control, or the prevention or correction of health problems. Crucially, to avoid skewing the results, the researchers intentionally excluded dogs that were neutered specifically because they already exhibited behavior problems, or if it was recommended by a veterinarian for behavioral reasons. By analyzing data from dogs neutered at various ages, up to 10 years old, the study could effectively compare the effects of early versus late neutering.
The Surprising Behavioral Outcomes
Contrary to the expectation that neutering would lead to improved behavior, the study found that many neutered male dogs exhibited less desirable behaviors. Out of 100 assessed behaviors, 40 showed statistically significant differences between neutered and intact dogs. While neutering did show positive effects in four areas – reduced indoor urine marking, less howling when left alone, increased likelihood of returning when called off-leash, and more reliable fetching – these were significantly outweighed by negative outcomes.
The most concerning results pertained to aggression. Neutered dogs were found to be more likely to display aggression towards delivery workers, strangers passing by their home, joggers, cyclists, rollerbladers, unfamiliar female dogs, unfamiliar people approaching the owner or family members, and when small animals entered their yard. alarmingly, the younger the dog was when neutered, the more pronounced these aggressive tendencies became.
Increased Fear and Anxiety in Neutered Dogs
Beyond aggression, neutered dogs also demonstrated a notable increase in fear-related behaviors. This included heightened responses to loud noises, unfamiliar situations, strange children, other dogs (whether barking, growling, or approaching), unfamiliar objects, windblown items, veterinary examinations, and nail clipping. Again, the negative impact of these fear-based behaviors was amplified in dogs that were neutered at a younger age.
Other undesirable behaviors that appeared more frequently in neutered dogs included eating feces, rolling in smelly substances, stealing food, persistent barking when alarmed or excited, and obsessive licking.
The Societal Paradox of Neutering
The overarching pattern from this research is clear: neutering male dogs appears to increase the likelihood of aggressive and fearful behaviors, as well as over-excitability and other miscellaneous undesirable actions. Early neutering, in particular, seems to exacerbate these negative effects.
The study’s authors highlight a significant societal paradox: while neutering is essential for controlling pet overpopulation and reducing the number of euthanized animals in shelters, it may inadvertently contribute to the very behaviors that lead to dogs being surrendered in the first place. Shelters are often overwhelmed with dogs displaying undesirable behaviors, and paradoxically, castration, which aims to reduce the number of unwanted dogs, might increase the incidence of these problem behaviors, making neutered dogs more vulnerable to abandonment. This underscores the need for a more informed approach to neutering recommendations, considering the potential behavioral impacts. For owners struggling with behavioral issues in their dogs, exploring options like behavior modification techniques for dogs can be a crucial step.
