K 9 F O R C E
P A G E 7
An Explanation of Veterinary Anti-Parasitic
So why does early spaying and neutering cause these increased
risks in our canine companions? This question is still being
researched, but it comes down to the gonadal (from ovaries or
testes) hormone secretions and how they interact with growth
and other biological mechanisms. When examining growth, it is
believed that spaying/neutering before maturity, before growth
plate closure of the long bones has occurred, can result in
growth longer than what would be considered normal. This
potential abnormal growth can result in abnormal loading and
wear on the joint, which, in some dogs, could lead to clinically
apparent joint disorders. Another concern is high luteinizing
hormone (LH), a reproductive-specific hormone produced by the
brain in response to no longer having a negative feedback
mechanism from the gonads (ovaries or testes). Essentially, this
means that the brain can no longer turn off production and, in
turn, produces concentrations up to thirty times higher than what
is observed in intact dogs.
A significant benefit to many owners, particularly pet owners, is
avoiding "sexual" behaviours or a heat cycle. However, recent
research shows that our traditional timing of spaying and
neutering before 6 months of age may carry an increased risk of
some debilitating joint disorders and certain cancers. Cancers
with some link to the timing of spaying and neutering include
lymphoma,
mast
cell
tumours,
hemangiosarcoma
and
osteosarcomas -- common cancers which many owners have
unfortunately experienced at some point during pet ownership.
Further, the joint conditions researched in association with early
spaying/neutering include hip dysplasia, cranial cruciate (knee)
ligament tear or rupture, and elbow dysplasia. The original
research examined the effects of spaying and neutering in three
of North America's most popular dog breeds: the Golden
Retriever, the Labrador Retriever and the German Shepherd. It
found that neutering before a year of age was associated with
increased risks of one or multiple joint disorders, 2-4 times more
than in their intact counterparts. A paper published by the
University of California Davis in 2020 examined multiple
research papers to assist veterinarians and pet owners in
making informed decisions across 29 different breeds and is
publicly available. This paper highlights the implications of when
to spay/neuter and suggests how best to proceed. However, it is
crucial to consider that these are suggestions and the individual
lifestyle of the dog, its owners and potential environmental/social
factors that may alter when spaying and neutering is ideal for
that particular dog.