BVA Journals: Neutering is no longer the hallmark of responsible ownership

She is especially keen for vets to understand the breadth of ways in which research has shown the reproductive system contributes to an animals physiology. Take for instance the role of luteinising hormone (LH), which is responsible for triggering ovulation in females and production of testosterone in males — and is a key research focus for Kutzler and colleagues at her lab.

“When we first started looking at it, we found luteinising hormone had receptors on lymphocytes, so these immune cells that are floating around and involved in everything from fighting off viruses, fighting off bacteria, to making antibodies. When we started to review the literature, ‘we found that other people before us had demonstrated there were these receptors in humans, laboratory animals and even in dogs.’

In itself, that didn’t necessarily mean a great deal. Just because a cell has a receptor for a certain hormone doesn’t mean that it actually does anything. If you think of a receptor asa lock and the hormone as the key, you could unlock the door and theres nothing behind it,” she explains.

Indeed, Kutzler suspects the general assumption had been that there was nothing behind the LH receptor lock on the lymphocyte door. ‘Not that there was any science behind it, but it was just: “Why would there be reproductive hormone receptors on lymphocytes? They must not be functional.”

To test the assumption, Kutzler and colleagues collected lymphocytes from both neutered and intact dogs. ‘We grew those lymphocytes in cultures and added increasing levels of LH to see what happened. Did it unlock the door and there was something behind there? Sure enough, what happens is LH induces neoplastic changes in lymphocytes. Among them are cell proliferation, cell adhesion and cell ‘migration into tissue.”

For Kutzler, this provides an explanation for a finding seen in research studies – that lymphoma, along with certain other cancers, occurs in much higher rates in neutered dogs.

“We know that there are a number of serious neoplastic diseases such as lymphoma, haemangiosarcoma, osteosarcoma that can develop after gonadectomy,” says Stefano Romagnoli, professor of small animal reproduction at the University of Padova; president of the Italian Society for Animal Reproduction; and chair of the World Small Animal Veterinary Association reproduction control committee.

“And we also know that some castrated dogs develop prostatic carcinoma. It’s strange; counterintuitive.

I’ve been recommending (with rare exceptions) against routine neutering of my male puppies for at least 25 years, because we knew it was bullshit.