Examining the Pros & Cons.

We hope this information will help dog owners make well-informed decisions in the best interests of the dog, the family and their future goals. 

There have been, and still are a lot of incorrect ideas about neutering. In the past twenty or more years, a number of scientific studies about the effects of spaying and neutering on a variety of different breeds, and some studies of the general dog population (including mixed breeds) have examined such things as:

  • Aggression
  • Cancers and other health issues
  • Joint problems & growth issues
  • Roaming behavior
  • Phobias
  • Other behavior issues

Studies demonstrate that commonly held beliefs that such things are “fixed” by “fixing”, are not correct.  In many cases, even the opposite is true.  Here are some findings:

  • Aggression toward humans:  A study of over 13,000 dogs determined that there was no change in aggressive behavior toward humans with the exception of heightened fear aggression toward strangers noted in some dogs neutered between 7-12 months of age.
  • Cancer:  A large study in Golden Retrievers demonstrated a significant increase in several cancers in neutered dogs.  Other studies have also demonstrated several cancers that appear more often in dogs that have been neutered.
  • Joint problems:  Studies have shown increases in hip dysplasia and cruciate ligament rupture in neutered dogs of both genders.  Early spay/neuter is especially problematic for skeletal and growth issues—the earlier the more problematic.
  • Roaming:  Believed to be decreased by neutering, a study of dogs in Chile determined that this was not the case. Other studies show 60% improvement in roaming behavior.
  • Phobias:  A study in Vizslas demonstrated an increase in fear-related behavior following neutering, including storm-related sound sensitivity.
  • Reactivity:  A German Shepherd Dog study demonstrated a heightened reactivity in bitches spayed between 5-10 months of age.  

Clearly there is more to be learned about behavioral changes related to spay/neuter.

So what are the pros and cons of spaying and neutering?  Here are a few to consider:

Spaying Females


  • No heat cycle to deal with
  • Eliminates hormone-related behavior changes
  • Cannot get pregnant & have puppies
  • Lower incidence of mammary tumors (if spayed before first heat)
  • Eliminates ovarian cancer or pyometra
  • Prevents phantom pregnancies
  • Have greater longevity than intact bitches (1 study)


  • Dangers of surgery & anesthesia
  • May eliminate a good dog for breeding
  • Higher incidence of orthopedic issues
  • Possible urinary incontinence
  • Increased risk of:
    • Hemangeosarcoma
    • Lymphoma
    • Mast cell cancers
  • Tendency for weight gain and obesity
  • Changes in coat texture
  • Potential increase in phobias
  • Potential increase in noise sensitivity

Neutering Males


  • Cannot impregnate bitches
  • Reduced risk of testicular cancer
  • May reduce inclination to roam (if hormonal)
  • May reduce urine marking (if hormonal)
  • May reduce mounting (if hormonal)
  • Reduced risk for non-cancerous prostate conditions
  • Reduced risk for perianal fistulas
  • Reduced dog aggression if hormone-related (not if it is fear-based or learned)


  • Dangers of surgery & anesthesia
  • Greater longevity than neutered dogs (1 study)
  • May eliminate a good dog for breeding
  • Increased risk of:
    • Prostate & bladder cancers
    • Hemangeosarcoma
    • Hypotyroidism
    • Orthopedic disorders
  • Neutered dogs may target intact dogs
  • Tendency for weight gain and obesity

Age for Neutering

Regardless of whether or not you choose to neuter your dog, we recommend postponing until your dog reaches physical maturity as hormones are important for healthy growth and skeletal soundness.  This would be after a bitch’s first heat cycle and at least 18 months of age for a male.  

If you are interested in researching further, Google Scholar is a good source for scientific studies. Ultimately whether or not and when to spay or neuter is a decision for each dog owner to make and discuss with your veterinarian. If you have any question about this, please speak to us.

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