Could you discuss delayed desexing and the alternatives like an ovary sparing procedure? It seems clear that in breeds like the GSD it benefits their health, but do we know much in regard to smaller breeds? (I know this topic can be controversial so if you'd prefer not to delve into it, or already have I understand) Also I've been loving the breed posts, thank you for taking the time to write them up!
don’t at all mind discussing the topic when everyone remains civil
about it. It’s very interesting and an aspect of veterinary medicine
that’s bound to change as we gather more information. I’m happy to
discuss it as long as all participants refrain from making personal
It’s a long discussion folks. I’d grab a cuppa tea if that’s your thing. Also, unfortunately I can’t hide it under a ‘read more’ because it’s an answer to an ask, and Tumblr will eat the hidden part if I do. I will try to make it look pretty if you’re not interested.
in dogs we have performed desexing (spey) by performing an
ovariohysterrectomy, removing both ovaries and the uterus. Some
alternatives have been suggested including tubal ligation, hysterectomy
(removing only the uterus), ovariectomy (removing only the ovaries) or
doing nothing. This is good. Science as a process should periodically
review data, question the knowledge base and make recommendations based
on new research. Otherwise it’s just dogma.
don’t think you can claim that it is ‘clear’ that leaving the ovaries
benefits the health of breeds like the GSD. The practice is still
controversial at best, with some veterinarians outright labeling it at
malpractice. There is some breed variability in terms of what relative
benefits and risks might be expected, but I really wouldn’t call it
Before I talk about various cancer risks, let’s talk about relative risks of non-cancerous conditions.
an ovariohysterectomy (traditional spey)that is properly performed, there is zero risk of
pyometra. Stump pyo can occur if remnants of the uterus or ovaries are
left behind. Cruciate tears are affected by multiple factors, but
desexed dogs seem more prone to them than entire dogs. Weight gain and
obesity is more common in desexed dogs.
The relative risk of pyometra in non-desexed dogs is about 25%. Risks typically increase with age.
an ovary sparing spey (hysterectomy), only the uterus is removed.
Pregnancy is prevented. Pyometra can still occur if any uterine or
cervix tissue remains (a stump pyo). With the apparent influence of oestrogen, these
dogs may be less at risk of cruciate disease and are less at risk of
an ovariectomy, only the ovaries are removed. This renders the dog
infertile and removes the influence of oestrogen. The uterus will
atrophy and shrink down without stimulation from female hormones,
rendering the risk of pyometra basically zero. It may still increase the
risk of obesity and cruciate disease like the traditional spey.
that pyometra is often lethal, while cruciate disease is painful but
treatable, personally I would err on the side of preventing pyometra.
Also keep in mind that obesity in dogs can be moderated with owner
control of the diet, and obesity will predispose to cruciate injury. I
would recommend removing at least the ovaries.
Male dogs have less surgical options. Vasectomy can be considered, but these dogs are basically entire but infertile.
entire male dog is more at risk of perineal hernia, benign prostatic
hyperplasia, perianal adenoma and inter-male aggression. A castrated
male dog is relatively more at risk of, again, obesity, cruciate
ligament disease, and possibly diabetes.
the information above, and I haven’t brought cancers into the equation
yet, you might wonder of preventing obesity in desexed dogs might reduce
the incidence of cruciate disease and subsequently other conditions
that we know are more common in obese dogs, namely cruciate ligament
disease and diabetes. You might conclude that there is little benefit to
leaving a dog entire if you’re able to control its weight.
think that’s a reasonable assumption so far, though it’s clear to me
that the benefits of traditional desexing are more pronounced in
Now lets talk about cancers.
are multiple types of cancer. Some are more devastating than others.
Some are more common than others. In terms of highly malignant cancers
that show up relatively commonly in dogs, the ones we talk most about,
and of most interest in this topic, are mammary cancer, haemangiosarcoma
(HSARC), Mast Cell Tumor (MCT) and osteosarcoma (OSC).
cancer is extremely common in entire female dogs. In European countries
where prophylactic desexing is not routinely performed mammary tumours
make up 50-70% of all cancers seen. They are relatively rare in
countries with a high desexing rate but extremely predictable in dogs
desexed late in life or not at all. Speying earlier appears more
protective compared to being left entire: speying before the first heat
reduces risk to 0.05%, before second heat to 8%, and before 3rd heat to
26%. after the third heat there is negligible reduction in risk of
mammary cancer compared to intact dogs.
may be three times (3x) more common in desexed large breed dogs.
Cell Tumors maybe up to three times (3x) more common in desexed dogs of
certain breeds. Lymphoma may be up to 10% more common in desexed dogs of
- Haemangiosarcoma may be more common in neutered dogs of
some breeds, but less common in neutered dogs of other breeds.
isn’t much consensus across ALL dog breeds in ALL situations. There are
numerous retrospective studies, and more coming out all the time
(Science!) but more data needs to be analysed.
is fairly clear is that there is a dramatic reduction in otherwise
common mammary cancers by early desexing of females. There is probably
some benefit in reducing other cancer risks to later desexng, or not desexing,
So do you? Or don’t you?
certainly more incentive to desex female dogs, as even pyometra on its
own is a sneaky, life threatening condition. I recommend desexing most
female dogs in their senior years if they haven’t already been done for
this reason alone.
you do chose to desex, and I’m talking about procedures that involve at
least removal of the gonads, it becomes a matter of when. If you don’t
remove the ovaries then you have no benefits from desexing other than
infertility. There’s no significant benefit in leaving the ovaries
compared to leaving the dog entire.
a small dog, OSC is incredibly rare. HSARC is rare. MCT can happen to
anything. We weight up those relatively low risks compared to the very
high risk of mammary cancer and pyometra, and I would advise speying
before the first heat. With males timing is not as critical unless
behavioural factors are involved.
a larger dog, I personally think it’s worth delaying desexing to between the first
and second heat. I would get too nervous about mammary cancers to wait
beyond the second heat but there may be some benefit in preventing
osteosarcoma by delaying surgery until more skeletal maturity, and same
for cruciate injuries.
(I have a theory that osteosarcoma occurs in its
predilection sites due to increased bio-mechanical forces in these
areas, so waiting for skeletal maturity before removing the gonads might
the other hand, screening for hip dysplasia and desexing if the dog
definitely has it so you can perform a JPS also has benefits, because
you’re addressing pathology the dog definitely has right now.
are so many unknowns in these hypothetical scenarios. This makes it a
challenge to make recommendations when clients just want the ‘right’
The best plan for the individual dog may depend on breed or
breed mix (genetic testing would be ideal, but an added cost) or any
known predispositions within the family or bloodlines.
this explanation is getting rather long, but there’s so much
interesting information on this topic and it’s growing all the time.
there is probably a benefit to delayed desexing in dogs prone to OSC,
cruciate injury and HSARC. Some of the other risks may be mitigated by
weight control. There is minimal if any benefit, and definitely some risk, in delaying
desexing for small breeds.
But this field may change as more information is gathered. It will be worth watching over the next decade.
shelters and rescues will always desex as young as possible, because
their primary aim is population control. They are justified in doing
this and their cases shouldn’t be considered in these scenarios.
(Majority of these statistics come from ‘The spay/neuter controversy’ presented at the OVMA by John Berg, DVM, DACVS and ‘ Long-term health effects of neutering dogs: comparison of Labrador Retrievers with Golden Retrievers‘ by Hart, Hart, et al)