This is what happens to your pet’s hormones after sterilisation, beyond reproduction

Understanding these hormonal changes is essential for responsible pet care. With the right adjustments in diet, activity, and routine, many of the unintended effects of sterilisation can be managed or even prevented. 

So which key hormones are affected after sterilisation?

Dr Deepraj Prajapati, senior veterinarian at RD Pet Hospital Ambeddkar Nagar, tells indianexpress.com, “After sterilisation, the most significant hormonal change is the reduction of sex hormones such as oestrogen in females and testosterone in males. These hormones do much more than regulate reproduction. They also influence metabolic rate, muscle mass, fat distribution, and appetite control.” 

When their levels drop, he says, many pets experience a natural slowdown in metabolism, which means they burn fewer calories than before. If food intake remains unchanged, this can gradually lead to weight gain. Over time, excess weight can increase the risk of joint issues, diabetes, and cardiovascular disease. On the positive side, the reduction in these hormones also lowers the risk of hormone-driven conditions such as mammary tumours, uterine infections, testicular cancer, and prostate enlargement, contributing to longer-term health benefits.

How post-sterilisation hormonal shifts impact behaviour

Sex hormones strongly influence behaviour, Dr Prajapati confirms, particularly mating and territorial instincts. After sterilisation, reduced testosterone in male dogs and cats often leads to decreased roaming, urine marking, and hormone-driven aggression. Females may show fewer mood fluctuations linked to heat cycles, which can reduce restlessness and vocalisation. 

Dr Prajapati states, “In many pets, this hormonal stabilisation results in calmer and more predictable behaviour. However, it is important to note that sterilisation does not erase learned behaviours or personality traits. Anxiety or fear-based aggression, for instance, is usually shaped by genetics, early experiences, and environment, and may still require behavioural training or enrichment alongside hormonal changes.”

Lifestyle changes pet parents should consider to support their pet’s hormonal balance

After sterilisation, Dr Prajapati notes that pet parents should focus on proactive lifestyle adjustments rather than waiting for weight or behaviour issues to appear. “Diet is the first area to review,” he says, adding that portion sizes often need to be reduced, or pets can be transitioned to nutritionally balanced, sterilisation-specific formulas that support a slower metabolism. 

“Regular, age-appropriate exercise becomes essential to maintain muscle mass and prevent fat accumulation. Mental stimulation through play, training, and enrichment is equally important, as calmer hormone levels do not eliminate a pet’s need for activity and engagement. Routine weight checks and veterinary follow-ups help detect subtle changes early, allowing timely adjustments that keep the pet healthy and active in the long run,” concludes the expert.