This week on the Cone…..

One veterinarian says to spay before the first heat cycle. Another says after the first heat cycle. A third says to spay after the second heat cycle.

How did we get to a place where there is so much disagreement? Why are recommendations changing? And most importantly, WHO IS RIGHT?!?

Let’s get into this episode!

female puppy wearing pink bow


  • There is no one single right answer…
    • Literature/research doesn’t agree with itself
    • Other factors to consider: age, breed, timing, the animals individual health factors
    • Neutering is only one factor in determining health outcome for an animal.
  • Before determining when, determine if and why the animal should be neutered first.
    • From a health perspective, what are the overall impacts of neutering?
    • Look at the individual patient as well as general risk factors.
  • Owners take very seriously that which they have control over (i.e. food, neutering) and can feel a pressure to make the “right” decision.
  • “…for male dogs I think we have a hard time really proving that there is a net health benefit to neutering them…for females I think there definitely is a net benefit and I think we can make that case pretty strongly” -Dr. McKenzie
  • Health is not the only factor: population control, unwanted animals, questions about behavior, local laws and regulations.


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COS 068 The Bloody Battle Over Grain-Free Diets


Dr. McKenzie has always pursued a wide range of interests both within and outside of science. After completing a bachelor’s degree with majors in English Literature and Biology at the University ofCalifornia at Santa Cruz, he obtained a Master’s in Physiology and AnimalBehavior and worked for several years in environmental and behavioral enrichment for captive primates.

Dr. McKenzie then attended the School of VeterinaryMedicine at the University of Pennsylvania and began working as a small animal general practice veterinarian. In addition to his clinical work, he has served as President of the Evidence-Based Veterinary Medicine Association, lectured on evidence-based medicine at numerous veterinary conferences, and published journal articles on such topics as overdiagnosis, cognitive bias in veterinary clinical decision-making, and the philosophical underpinnings of evidence-based and alternative medicine. Since 2009, Dr. McKenzie has managed the SkeptVet Blog and associated social media outlets, including a series of science-based pet health videos on YouTube. He has also been an occasional contributor to the popular Science-based Medicine blog.

While working as a practitioner, speaking, handwriting, Dr. McKenzie has continued to pursue post-graduate training, and in2015 he completed his MSc in Epidemiology at the London School of Hygiene and TropicalMedicine in 2015. He also teaches veterinary students in his practice as well as undergraduate biology majors, he writes a monthly column on evidence-based medicine for Veterinary Practice News magazine, and he has published a book forpet owners and veterinary professionals—Placebos for Pets? The Truth aboutAlternative Medicine in Animals.

In his sparse free time, Dr. McKenzie enjoys reading, hiking, playing his mandolin and guitar, travelling with his family, and sitting on the couch with his dogs watching the hummingbirds and woodpeckers outside his living room window.

Editor: Dustin Bays
@Bays4Bays Twitter/Instagram