Testosterone!

[SnowWa]

Do we have any endocrinologists in the group?

I found this interesting and do have a friend who is an endocrinologist (MD) and am going to ask her about this.

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I read an article that said - I am paraphrasing:

When an unneutered male pup reaches puberty and his "testosterone" kicks in --it is a hormone that signals maturity and slows growth.

If we neuter our little males prior to their "testosterone kicking in" -- they will not receive this hormone (which slows down their growth), and they will continue to grow for a longer period of time -- and will become larger.

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We are talking about only a moderate difference in size --

But isn't this interesting????

Carol Jean

[mustangbee]

Yes, very

[livingdustmops]

I posted this on another thread but you might want to review this information.

Here are two sources for more up to date information (2000-2002). The first one you might have to register but it is free and you might enjoy the website.

http://www.ivis.org/signin.asp?url=h...s.org/home.asp

In: Recent Advances in Small Animal Reproduction, Concannon P.W., England G., Verstegen III J. and Linde-Forsberg C. (Eds.)
International Veterinary Information Service, Ithaca NY (www.ivis.org), 2000; A1201.0400
Prepuberal Gonadectomy - Early-Age Neutering of Dogs and Cats (Last Updated: 25-Apr-2000)
L. M. Howe1 and P. N. Olson2
1College of Veterinaty Medicine, Texas A&M University, College Station, Texas, USA.
1Guide Dogs for the Blind, Inc., San Rafael California, USA.
Growth
Many veterinarians once held the belief that puppies and kittens neutered at early ages might be stunted in growth. Several research studies have now refuted these once-held beliefs. In a 15-month study conducted at the University of Florida, the effects of prepubertal gonadectomy on skeletal growth, weight gain, food intake, body fat, and secondary sex characteristics were investigated in 32 mixed-breed dogs [4]. Growth rates were unaffected (P>0.05) by gonadectomy, but the growth period in final radial/ulnar length was extended in all neutered male dogs (neutered at 7 weeks or 7 months) and in bitches neutered at 7 weeks of age. Thus, animals were not stunted in growth but were actually slightly (as determined by radiographs) taller. In a similar study at the same university [5], thirty-one cats were neutered at 7 weeks or 7 months or left intact. No differences (P>0.05) were detected between neutered cats, regardless of when they were neutered, for mature radius length or time of distal radial physeal closure. Distal radial physeal closure was delayed (P<0.05) in neutered cats when compared to intact cats. Similar findings in cats were reported by work from the University of Minnesota [6]. In males and females, distal radial physeal closure was delayed (P<0.01) in both groups of neutered cats (neutered at 7 weeks or 7 months of age) compared to intact animals. In female cats, proximal radial physeal closure was also significantly delayed (P=0.02) in cats neutered at 7 weeks of age.

http://www.angelswish.org/documents/SpayNeuterPaper.pdf

A 15-month study on the effects of prepubertal gonadectomy on skeletal growth, weight gain, food intake, body fat, secondary sex characteristics, and behavioral development in 32 mixed breed dogs. The study divided dogs into 3 groups: group 1 was neutered at 7 weeks of age, group two at 7 months of age, and group three unaltered.
 Skeletal growth: Greater in those neutered at 7 weeks than at 7 months; greater in 7 week old females than the males
 Body weight: Unaffected
 Food intake: Unaffected
 Secondary sex characteristics: Did not “grossly appear to reflect differences” Group of 7 week old had mean of 17.8mm; 7 months had mean of 16.8mm; and unaltered were a mean of 19.8mm
 “Concluded that neutering pups at 7 weeks affected skeletal, physical, and behavioral development much the same as did neutering pups at 7 months.”

[SnowWa]

Livingdustmops - That was an interesting article - wish I had kept the source for the article I read...

I understand "physeal closure" very well. I have seen hundreds of x-rays and have typed hundreds of reports - taken for bone-age purposes - and am familiar with the age-gradings in relation to "epiphyseal (physeal) closure."

The article I read was directed more toward the endocrinological aspect of growth...and the effect of testosterone on growth.

Interestingly, bone-age determination studies (epiphyseal closure analysis) are done on females as well as males. And - these studies, of course, are done on people with no regard whatsoever to their being neutered or spayed. These studies are often done to assess the growth pattern of children - in an effort to determine whether their growth is behind, normal, or ahead of their chronological age. And, the results of these studies often help an endocrinologist know whether or not growth hormones are indicated or might be beneficial. And, they are often done only to assess what the adult size might be for an unusually small child.

These articles are all very interesting... Thank you again for your article.

Carol Jean