Page 26 - Chow Life - Winter 2017

Sterilization

Considerations By Jeff Grognet, DVM
A comprehensive look at the pros and cons of early sterilization

When you send your puppies to new proven. The original study did not
homes, what are you telling your new suggest this or the issue of changes in
owners to do about sterilization? Do joint angle.
you push for a pediatric spay or neuter? Another reviewer, Laura J. Sanborn,
Does delaying until after the pup is a who did an extensive review of the
year old make sense to you? Or do you literature, suggests the twofold increase
recommend the traditional 6-month in risk of ligament rupture in early-
surgery? Weeding through the mass of sterilized dogs could be due to obesity
information and knowing which data associated with the surgery.
can be relied on is difficult.
Zink also suggests that hip dysplasia
The problem with much of the (HD) incidence could be affected by
available information is that it is early sterilization. One study showed
based on personal opinion. Like a that pups sterilized before 5½ months
statistician playing with numbers, the of age had a 6.7 percent incidence while
data on sterilization can be interpreted those sterilized at a traditional age had
differently, depending on what he is a 4.7 percent incidence. But Howe
trying to prove. Some reviewers make points out another revealed statistic in
assumptions that are difficult to back the same study: Dogs sterilized later
up. were three times more likely to be
For example, according to euthanized for the condition than the
veterinarian Dr. Chris Zink, early early age group. The authors suggest
sterilization (well before 6 months that early age sterilization may be
old) has been linked with a high associated with a less severe form of
incidence of cruciate ligament rupture HD.
in knees. The reason quoted is that
sterilization delays closure of the
bone-growth plates. This, Reducing Cancer Risk
according to Zink, creates A long-held justification for spaying
disproportionate bone before the first heat is the bitch’s
growth that ends in predisposition to mammary cancer.
undue angulation Mammary tumors possess estrogen
of the stifle. This receptors so the risk of mammary
increases stress cancer rises as the bitch goes through
on the ligament, more heat cycles.
predisposing it to Zink says, “While about 30 percent
rupture. of mammary cancers are malignant, as
Dr. Lisa Howe, in humans, when caught and surgically
a veterinary removed early, the prognosis is very
surgeon at Texas good.” Howe suggests the rate of
A&M, says that malignancy is closer to 50 percent and
even though the a significant problem in the female dog.
growth plates The odds ratio (relative risk) of
do close later in developing mammary cancer is based
early sterilized dogs, on comparing the risk in a subgroup
disproportionate bone to the risk in intact females. The risk
growth has not been
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