08/28/2025
Need more research about why we should not be castrating our working animals prior to age 3? Here’s a start.
Obesity
Being overweight in middle age shortened lifespan in tens of thousands of neutered pet dogs, underscoring the harm when neutering predisposes to weight gain.
�Salt C, et al. Association between life span and body condition in neutered client-owned dogs. J Vet Intern Med. 2019. https://onlinelibrary.wiley.com/doi/10.1111/jvim.15367$1
Gonadectomized dogs were significantly more likely to be diagnosed as overweight than intact dogs, particularly within the first two years after surgery.�Lefebvre SL, et al. Effect of age at gonadectomy on the probability of dogs becoming overweight. J Am Vet Med Assoc. 2013. https://avmajournals.avma.org/view/journals/javma/243/2/javma.243.2.236.xml$1
Early gonadectomy is linked to behavioral changes that can indirectly promote weight gain and obesity.�Palestrini C, et al. Influence of Gonadectomy on Canine Behavior. Animals (Basel). 2021. https://pubmed.ncbi.nlm.nih.gov/33672498/$1
Neutered dogs in France are at higher risk for obesity due to hormonal and metabolic shifts.�Colliard L, et al. Risk factors for obesity in dogs in France. J Nutr. 2006. https://pubmed.ncbi.nlm.nih.gov/16772466/$1
Australian veterinary data show neutered dogs have a significantly higher prevalence of obesity.�McGreevy PD, et al. Prevalence of obesity in dogs examined by Australian veterinary practices and the risk factors involved. Vet Rec. 2005. https://pubmed.ncbi.nlm.nih.gov/15923551/$
Increased food intake following gonadectomy strongly contributes to weight gain in male cats.�Kanchuk ML, et al. Weight gain in gonadectomized normal and lipoprotein lipase-deficient male domestic cats. J Nutr. 2003. https://pubmed.ncbi.nlm.nih.gov/12771331/$1
Leptin dysregulation following neutering promotes body fat accumulation and reduced energy expenditure.�Martin L, et al. Leptin, body fat content and energy expenditure in intact and gonadectomized adult cats. J Anim Physiol Anim Nutr. 2001. https://pubmed.ncbi.nlm.nih.gov/11686788/$1
Dietary fat exacerbates post-neuter weight gain, leading to increased adiposity and reduced lean mass.�Nguyen PG, et al. Effects of dietary fat and energy on body weight and composition after gonadectomy in cats. Am J Vet Res. 2004. https://pubmed.ncbi.nlm.nih.gov/15631038/$1
S*x and reproductive status significantly influence feeding behavior and body weight regulation.�Houpt KA, et al. Effect of s*x and reproductive status on sucrose preference, food intake, and body weight of dogs. J Am Vet Med Assoc. 1979. https://pubmed.ncbi.nlm.nih.gov/571424/$1
Large-scale surveys show neutered pets consistently experience higher obesity rates than intact counterparts.�Lund EM, et al. Prevalence and risk factors for obesity in adult dogs from private US veterinary practices. Int J Appl Res Vet Med. 2006. https://opis-cdn.tinkoffjournal.ru/mercury/expensive-dogs-Lund.pdf$1
In conclusion, this study shows that the risk of cranial cruciate ligament disease in dogs is linked to how long they are exposed to natural s*x hormones, and the relationship isn’t simple or linear. The highest risk was seen when females were spayed before about 1054 days (just under 3 years) and males before about 805 days (a little over 2 years). These results may help define what counts as “early” spay or neuter when it comes to cranial cruciate ligament disease risk.
Veterinary reproduction specialists now recommend hormone-preserving sterilization: preventing unwanted litters & less risk of torn cruciates.
