For decades, spaying and neutering have been seen as the responsible choice for dog owners. But today, with growing research and changing attitudes, many are rethinking the routine removal of a dog’s reproductive organs, known medically as gonadectomy.
So what’s best for your dog: intact or neutered/spayed? Like most things in dog care, it depends.

What Is Gonadectomy?

Gonadectomy refers to the surgical removal of the gonads, ovaries in females (spaying), and testicles in males (neutering). It eliminates a dog’s ability to reproduce, and drastically alters hormone production.
Historically, the procedure has been promoted for population control and behaviour management. But is it always necessary?

Pros of Spaying/Neutering

. Prevents unwanted litters and reduces stray dog populations;
. Eliminates the risk of certain cancers (testicular, ovarian, uterine);
. Can reduce hormone-driven behaviours like roaming or marking;
. May make multi-dog households easier to manage.

The Other Side: Benefits of Keeping Dogs Intact

New studies now suggest that removing sex hormones too early can impact a dog’s long-term health, especially for large breeds. Hormones like testosterone, oestrogen, and progesterone influence not just reproduction, but bone growth, metabolism, immunity, and even behaviour.

Potential benefits of keeping dogs intact:

. Lower risk of certain joint disorders and cancers in some breeds;
. More stable physical and emotional development;
. Better muscle tone and endurance (especially in working or sporting dogs);
. In some cases, more balanced temperament and confidence.

But keeping a dog intact also requires more responsibility. Owners must manage:

. Heat cycles in females (and the attention they draw);
. Preventing unplanned mating;
. Potential for dominance or reactivity if left untrained.

What Does the Science Say?

Studies from UC Davis and other veterinary schools suggest that breed, size, and sex all influence how gonadectomy affects health outcomes. For example, spaying a Golden Retriever before 1 year of age is associated with a significantly higher risk of joint issues and certain cancers, whereas smaller breeds may be less affected.

Hormonal Changes After Neutering

When a male dog is neutered (orchiectomy), the testes, which produce Testosterone, are removed. This causes a cascade of hormonal changes involving the Luteinising hormone (LH) and other endocrine signals.
Under normal circumstances, testosterone provides negative feedback to the pituitary gland, regulating LH production. Once the testes are removed, this feedback loop disappears, and the pituitary gland may continue to produce persistently elevated levels of LH.

Possible Effects on Scent Profile

Some researchers and clinicians have proposed that the hormonal changes following neutering mayalter a dog’s scent profile. In some cases, neutered males may emit chemical cues that are less clearly “male” to other dogs. As a result:

. They may be investigated more frequently by other dogs;
. They may attract mounting behaviour from both males and females;
. They may experience increased social tension during dog interactions.
This phenomenon is not universally observed, but it is reported by many trainers and behaviour professionals working with intact and neutered dogs in social environments.

Behavioural Consequences

In some cases, this altered chemical signalling may contribute to behavioural issues such as:

. Increased unwanted attention from other dogs;
. Social stress during group interactions;
. Defensive reactivity;
. Escalation of mounting or harassment behaviours in dog groups.
It is important to note that behaviour is influenced by multiple factors, including genetics, learning history, early socialisation, and environment. Hormones are only one component of a complex behavioural system.

My Professional Perspective

Having worked with countless dogs, I’ve seen both sides. Some neutered dogs are calm and balanced, others become anxious or less confident. Some intact males are pushy and hard to manage, while others are excellent companions.
The real key? Training, boundaries, structure, and understanding your individual dog.
If you choose to delay or avoid gonadectomy, make sure you:

. Invest in early training and socialisation;
. Provide mental stimulation and regular exercise;
. Are proactive about managing behaviour and sexual maturity.

Want to Learn More?

I explore this topic in greater depth in my upcoming book, where I discuss the behavioural, emotional, and physical impact of hormones on dogs, and how to make informed choices for your pet.“Dog Training. The Holistic Way” (Available now on Amazon)

My Final Thoughts

Whether you decide to neuter or not, the most important thing is to make a conscious, informed choice not just follow tradition or public pressure. Talk to your vet, read the latest research, and observe your dog. Every dog is different, and what works for one may not work for another.
If you’re unsure or would like to discuss how behaviour training can support your dog, intact or neutered, feel free to reach out.