Quote:
Early spaying is detrimental to a dogs skeletal and endocrine system. A Toy breed is ok to spay/neuter around a year old, however any dog larger than that should be allowed to mature more than a year before spay or neuter.
There is actually no evidence that I know of to support this. There is definitely evidence to support delaying spaying of giant breed dogs, but studies have shown that they really just need to get past puberty. So whether it is one year or two doesn't seem to matter. Spaying prior to the first heat has been shown to greatly reduce the incidence of mammary tumors and that benefit decreases with each cycle. So right around a year gives them as much benefit with the least risk.
I have seen the effects of early spay and neuter myself, and I have also read about the effects of it. I would rather have a mature animal, mentaly and physicaly before spaying or neutering. Being a trainer I often work with Vets in the greater Seattle area and they have told me to my face about the negative effects of early spay and neuter. Many Vets in my area are so on board with what it does to an animal that they are no longer offering spaying or neuter before 12 months. I would rather wait the full 24 months before getting it done but to me the 12 months is really a step in the right direction.
I guess that I am also coming from a working dog owner and trainers corner on this. For training in a working sport its good to be able to see your dog mature fully and physicaly to ensure the dogs potential. However, even with my toy dogs, I have waited till nearly a year before neutering.
here is an interesting article spelling out the physical effects, both positive and negative of spay and neuter. However, the effects go much beyond just the physical traits of the animal. Behavior is greatly effected too, sometimes its good and sometimes its bad.
http://www.naiaonline.org/pdfs/LongTermHealthEffectsOfSpayNeuterInDogs.pdf
http://www.caninesports.com/SpayNeuter.html -- another good article, written by a Vet
