Study: Restoring Hormone Levels in Neutered Dogs Improves Health

Study: Restoring Hormone Levels in Neutered Dogs Improves Health

This case study was published in Topics in Companion Animal Medicine. It details the first report of hormone restoration therapy in a dog battling both physical and psychological symptoms as a result of castration.

This resulted in normal levels of testosterone and luteinizing hormone, improved mobility, and a reduction in anxiety.

Spaying and neutering and the disruption of hormones

Pet overpopulation in the United States includes spaying and neutering with other benefits listed including a decrease in diseases related to sex organs such as mammary, ovarian, and testicular cancers, pyometra, and prostate disorders. Research has also shown that this also has a significant mental and physical impact leading to obesity, cognitive and behavioral problems, urinary incontinence, immune-mediated disease, and so forth as a result of unregulated natural hormone feedback mechanisms. The alternative is hormones-sparing sterilization, eg, hysterectomy, and vasectomy. For the already spayed and neutered, hormone treatment may be an option.

Background and health issues

Toby, a mixed breed dog, was castrated at about 7 months of age before joining his new family. When he arrived, he was active and healthy, however, his health rapidly deteriorated. At 12 months, he had reduced mobility, rapid weight gain, reclusion, and a limp in the right hip. Over the course of three years, he was treated with pain medication, joint supplements, thyroxine, antidepressant, and significant diet restrictions. Anxiety worsened and mobility was still poor.


By age four, Toby was reclusive due to extreme anxiety and lack of mobility due to extreme weight gain. A decision was made, working with Dr. Michelle Kutzler, a veterinary theriogenologist at Oregon State University, to try hormone therapy to restore his hormones to a normal level.

When castrated, male dogs have low testosterone and high LH. Toby’s LH was 3 times that. His weekly regimen included testosterone shots coupled with positive reinforcement training. After three months, his muscle mass increased which reduced limping and improved mobility. Fear and anxiety improved. LH remained high, therefore a gonadotropin-releasing hormone (GnRH) agonist was implanted, which worked. His appetite was reduced, as was his fear of people. He was able to go to the park and keep up with other dogs. There have been no known side effects.


Hormone restoration may be effective in improving health in neutered dogs, though the data from one animal cannot be used for all. Controlled randomized clinical trials and further research are needed.

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