Your new vet is following current evidence. Your old vet is following 1990s standard-of-care. This is one area where veterinary recommendations have meaningfully shifted in the past 10-15 years.

The data: Hart et al. at UC Davis published a series of studies (2014, 2020, and a 35-breed analysis 2023) tracking joint disease, cancer rates, and behavioral outcomes by spay/neuter age. The findings for large and giant breeds — particularly Goldens, Labradors, GSDs, Rottweilers, and Vizslas — are robust:

• Neutering male Goldens before 12 months increased odds of one or more joint disorders (hip dysplasia, CCL rupture, elbow dysplasia) by 4-5x compared to intact controls.
• Cancer risk (specifically lymphoma, mast cell tumor, hemangiosarcoma) was elevated in early-neutered Goldens, particularly females spayed before 1 year.
• Effect sizes were breed-specific — smaller breeds showed minimal or no joint impact from early neuter, while large breeds showed substantial effects.

Current consensus for large/giant breeds: wait until growth plates close (typically 12-18 months for large breeds, 18-24 for giants) before neutering, unless there’s a specific behavioral or medical indication to do earlier. For females, the trade-off includes mammary cancer risk reduction (greater with earlier spay) versus joint and cancer risks of early spay — for most large breeds, the joint/cancer side outweighs the mammary side now that we have better treatment for mammary tumors when they occur.

For your Golden specifically: wait. 18-24 months is well-supported by the breed-specific Davis data. If behavioral issues emerge (intermale aggression, marking that can’t be managed), the conversation changes. But absent those, the wait is the better default.

References:

• Hart BL, Hart LA, Thigpen AP, Willits NH. Long-term health effects of neutering dogs. PLoS One 2014; 9(7): e102241.
• Hart BL et al. Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs. Frontiers Vet Sci 2020.