[ SHOWGSD-L ] Early Spay-Neuter Considerations
- From: MORGAN LEWIS <shadowland22000@xxxxxxxxx>
- To: gsd showlist <showgsd-l@xxxxxxxxxxxxx>
- Date: Sun, 23 May 2010 07:47:28 -0700 (PDT)
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Early Spay-Neuter Considerations for the Canine Athlete
One Veterinarianâ??s Opinion
© 2005 Chris Zink DVM, PhD, DACVP
www.caninesports. com
Those of us with responsibility for the health of canine athletes need to
continually read and evaluate new
scientific studies to ensure that we are taking the most appropriate care of
our performance dogs. This article
provides evidence through a number of recent studies to suggest that
veterinarians and owners working with
canine athletes should revisit the standard protocol in which all dogs that are
not intended for breeding are
spayed and neutered at or before 6 months of age.
Orthopedic Considerations
A study by Salmeri et al in 1991 found that bitches spayed at 7 weeks grew
significantly taller than those spayed
at 7 months, who were taller than those not spayed (or presumably spayed after
the growth plates had closed).(1)
A study of 1444 Golden Retrievers performed in 1998 and 1999 also found bitches
and dogs spayed and
neutered at less than a year of age were significantly taller than those spayed
or neutered at more than a year of
age.(2) The sex hormones, by communicating with a number of other
growth-related hormones, promote the
closure of the growth plates at pubjerty (3), so the bones of dogs or bitches
neutered or spayed before puberty
continue to grow. Dogs that have been spayed or neutered well before puberty
can frequently be identified by
their longer limbs, lighter bone structure, narrow chests and narrow skulls.
This abnormal growth frequently
results in significant alterations in body proportions and particularly the
lengths (and therefore weights) of certain
bones relative to others. For example, if the femur has achieved its
genetically determined normal length at 8
months when a dog gets spayed or neutered, but the tibia, which normally stops
growing at 12 to 14 months of
age continues to grow, then an abnormal angle may develop at the stifle. In
addition, with the extra growth, the
lower leg below the stifle likely becomes heavier (because it is longer), and
may cause increased stresses on the
cranial cruciate ligament. In addition, sex hormones are critical for achieving
peak bone density.(4) These
structural and physiological alterations may be the reason why at least one
recent study showed that spayed and
neutered dogs had a higher incidence of CCL rupture.(5) Another recent study
showed that dogs spayed or
neutered before 5 1/2 months had a significantly higher incidence of hip
dysplasia than those spayed or neutered
after 5 1/2 months of age, although it should be noted that in this study there
were no standard criteria for the
diagnosis of hip dysplasia.(6) Nonetheless, breeders of purebred dogs should be
cognizant of these studies and
should consider whether or not pups they bred were spayed or neutered when
considering breeding decisions.
Cancer Considerations
A retrospective study of cardiac tumors in dogs showed that there was a 5 times
greater risk of
hemangiosarcoma, one of the three most common cancers in dogs, in spayed
bitches than intact bitches and a
2.4 times greater risk of hemangiosarcoma in neutered dogs as compared to
intact males.(7) A study of 3218
dogs demonstrated that dogs that were neutered before a year of age had a
significantly increased chance of
developing bone cancer.(8) A separate study showed that neutered dogs had a
two-fold higher risk of developing
bone cancer.(9) Despite the common belief that neutering dogs helps prevent
prostate cancer, at least one study
suggests that neutering provides no benefit.(10) There certainly is evidence of
a slightly increased risk of
mammary cancer in female dogs after one heat cycle, and for increased risk with
each subsequent heat. While
about 30 % of mammary cancers are malignant, as in humans, when caught and
surgically removed early the
prognosis is very good.(12) Luckily, canine athletes are handled frequently and
generally receive prompt
veterinary care.
Behavioral Considerations
The study that identified a higher incidence of cranial cruciate ligament
rupture in spayed or neutered dogs also
identified an increased incidence of sexual behaviors in males and females that
were neutered early.(5) Further,
the study that identified a higher incidence of hip dysplasia in dogs neutered
or spayed before 5 1/2 months also
showed that early age gonadectomy was associated with an increased incidence of
noise phobias and
undesirable sexual behaviors.(6) A recent report of the American Kennel Club
Canine Health Foundation reported
significantly more behavioral problems in spayed and neutered bitches and dogs.
The most commonly observed
behavioral problem in spayed females was fearful behavior and the most common
problem in males was
aggression.(12)
Other Health Considerations
A number of studies have shown that there is an increase in the incidence of
female urinary incontinence in dogs
spayed early (13), although this finding has not been universal. Certainly
there is evidence that ovarian hormones
are critical for maintenance of genital tissue structure and contractility.
(14, 15) Neutering also has been
associated with an increased likelihood of urethral sphincter incontinence in
males.(16) This problem is an
inconvenience, and not usually life-threatening, but nonetheless one that
requires the dog to be medicated for life.
A health survey of several thousand Golden Retrievers showed that spayed or
neutered dogs were more likely to
develop hypothyroidism.(2) This study is consistent with the results of another
study in which neutering and
spaying was determined to be the most significant gender-associated risk factor
for development of
hypothyroidism. (17) Infectious diseases were more common in dogs that were
spayed or neutered at 24 weeks or
less as opposed to those undergoing gonadectomy at more than 24 weeks.(18)
Finally, the AKC-CHF report
demonstrated a higher incidence of adverse reactions to vaccines in neutered
dogs as compared to intact.(12)
I have gathered these studies to show that our practice of routinely spaying or
neutering every dog at or before
the age of 6 months is not a black-and-white issue. Clearly more studies need
to be done to evaluate the effects
of prepubertal spaying and neutering, particularly in canine athletes.
Currently, I have significant concerns with spaying or neutering canine
athletes before puberty. But of course,
there is the pet overpopulation problem. How can we prevent the production of
unwanted dogs while still leaving
the gonads to produce the hormones that are so important to canine growth and
development? One answer
would be to perform vasectomies in males and tubal ligation in females, to be
followed after maturity by
ovariohysterectomy in females to prevent mammary cancer and pyometra. One
possible disadvantage is that
vasectomy does not prevent some unwanted behaviors associated with males such
as marking and humping. On
the other hand, females and neutered males frequently participate in these
behaviors too. Really, training is the
best solution for these issues. Another possible disadvantage is finding a
veterinarian who is experienced in
performing these procedures. Nonetheless, some do, and if the procedures were
in greater demand, more
veterinarians would learn them.
I believe it is important that we assess each situation individually. For
canine athletes, I currently recommend that
dogs and bitches be spayed or neutered after 14 months of age.
References:
1. Salmeri KR, Bloomberg MS, Scruggs SL, Shille V.. Gonadectomy in immature
dogs: effects on skeletal,
physical, and behavioral development. JAVMA 1991;198:1193- 1203
2. http://www.grca. org/healthsurvey .pdf
3. Grumbach MM. Estrogen, bone, growth and sex: a sea change in conventional
wisdom. J Pediatr Endocrinol
Metab. 2000;13 Suppl 6:1439-55.
4. Gilsanz V, Roe TF, Gibbens DT, Schulz EE, Carlson ME, Gonzalez O, Boechat
MI. Effect of sex steroids on
peak bone density of growing rabbits. Am J Physiol. 1988 Oct;255(4 Pt
1):E416-21.
5. Slauterbeck JR, Pankratz K, Xu KT, Bozeman SC, Hardy DM. Canine
ovariohysterectomy and orchiectomy
increases the prevalence of ACL injury. Clin Orthop Relat Res. 2004
Dec;(429):301- 5.
6. Spain CV, Scarlett JM, Houpt KA. Long-term risks and benefits of early-age
gonadectomy in dogs. JAVMA
2004;224:380- 387.
7. Ware WA, Hopper DL. Cardiac tumors in dogs: 1982-1995. J Vet Intern Med 1999
Mar-Apr;13(2) :95-103
8. Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters D,
Cancer Epidemiol Biomarkers
Prev. 2002 Nov;11(11):1434- 40
9. Ru G, Terracini B, Glickman LT. Host related risk factors for canine
osteosarcoma. Vet J. 1998 Jul;156(1):31-
9.
10. Obradovich J, Walshaw R, Goullaud E. The influence of castration on the
development of prostatic carcinoma
in the dog. 43 cases (1978-1985). J Vet Intern Med 1987 Oct-Dec;1(4) :183-7
11. http://www.akcchf. org/pdfs/ whitepapers/ Biennial_ National_ Parent_Club_
Canine_Health_ Conference. pdf
12. Meuten DJ. Tumors in Domestic Animals. 4th Edn. Iowa State Press, Blackwell
Publishing Company, Ames,
Iowa, p. 575
13. Stocklin-Gautschi NM, Hassig M, Reichler IM, Hubler M, Arnold S. The
relationship of urinary incontinence to
early spaying in bitches. J. Reprod. Fertil. Suppl. 57:233-6, 2001
14. Pessina MA, Hoyt RF Jr, Goldstein I, Traish AM. Differential effects of
estradiol, progesterone, and
testosterone on vaginal structural integrity. Endocrinology. 2006
Jan;147(1):61- 9.
15. Kim NN, Min K, Pessina MA, Munarriz R, Goldstein I, Traish AM. Effects of
ovariectomy and steroid
hormones on vaginal smooth muscle contractility. Int J Impot Res. 2004
Feb;16(1):43- 50.
16. Aaron A, Eggleton K, Power C, Holt PE. Urethral sphincter mechanism
incompetence in male dogs: a
retrospective analysis of 54 cases. Vet Rec. 139:542-6, 1996
17. Panciera DL. Hypothyroidism in dogs: 66 cases (1987-1992). J. Am. Vet. Med.
Assoc., 204:761-7 1994
18. Howe LM, Slater MR, Boothe HW, Hobson HP, Holcom JL, Spann AC. Long-term
outcome of gonadectomy
performed at an early age or traditional age in dogs. J Am Vet Med Assoc. 2001
Jan 15;218(2):217- 21
Morgan and His Angels
Precious, OFA
Princess, CGC, TDI, GSDCA Health Award
"So Much to Do, So Little Time"
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