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"Fixing" your animal companion - the great contradiction

     Have you ever wondered why spaying and neutering a dog or cat is called “fixing”? 

If you were raised on a farm you might know the answer to that question.  Males who have their gonads can be problematic, right?  Remove those and the animal is “fixed”.  This very general rule might make sense in the mind of a farmer with a male donkey or horse who is trying to jump on everything.  However, when it comes to our companion animals, there is a growing body of evidence proving that we are not “fixing” much when we neuter and spay them, especially before maturity, and in fact the opposite holds true for the vast majority of health issues, including behaviour!

     If that is the case, then why do we continue to do it?  To answer that question, let us look at some history!  About a hundred years ago dogs and cats were becoming a lot more popular as household pets but there wasn’t a humane and reliable way to control the pet population, and the number of unwanted animals exploded.  Prior to the 1970’s, the few shelters that did exist were overrun by strays.  It was about that time that the first low cost spay/neuter clinics started opening in North America, spurring discussions about the benefits of spaying and neutering and advocating for the procedure as an animal welfare issue.  Several decades of aggressive campaigning (thank you Bob Barker) entrenched spay and neuter in the public mindset as being not only for the better health of the animal but as a means of reducing the number of unwanted dogs and cats, and shelters required sterilization for all animals prior to adoption.  It is heart wrenching to know that puppies and kittens are today being spayed and neutered when they are just a few weeks old.  How can this not be affecting their development and long term health? 


     The concept of removing the reproductive organs before maturity (usually at 6 months of age or before a female has her first heat) to control the pet population, and possibly make dogs and cats more manageable, did not take into consideration the negative physiological consequences.  The most obvious physical affect is the influence of hormones on the growth plates.  In a developing puppy or kitten, major growth happens between 3 and 6 months.  Most animals achieve 90% of their adult size by the end of 9 months of age.  Most growth plates close between 4 and 12 months depending on the anatomical structure, size and breed.  In large and giant breeds the plates might not close until 15-18 months of age. The growth plates of the long bones are the last to close.  The average size dog (25-30 kg / 55-65 lbs) will continue to see growth of those bones until 11-12 months of age.  In an animal who is neutered or spayed before maturity, the growth plates, especially of those long bones, take longer to close in the absence of the sex hormones, often resulting in an animal who is taller, with abnormal musculoskeletal structure.


     One of the most common reasons cited for spaying a female before her first heat is to reduce the risk of mammary tumours.  In 2012 a meta-analysis of the medical literature was undertaken in the UK and published in the Journal of Small Animal Practice.  Its’ authors discovered that many frequently cited references were over 40 years old.  They concluded that due to the limited evidence available and risk of bias in the studies, that the evidence that spaying reduces risk of mammary tumours and that the age at spay has an effect, was weak and not sound basis for firm recommendations.  They recommended further research and association between mammary tumours and spaying should focus on recording age, breed, previous exposure to synthetic ovarian steroids, age at time of spay and how many years she had been a spayed female before tumours developed.

     Another study led by a team of researchers at the University of Pennsylvania State School of Veterinary Medicine, published in October 2019, looked at the role estrogen plays in development of mammary tumors in dogs. 159 shelter dogs with mammary cancer were studied, 29 of whom were still intact. 

Here is an excerpt from an article in Science Daily from November 1, 2019:

    Estrogen's role in canine mammary cancer is more complex than previously understood, according to new research. The nuanced findings may help explain why dogs spayed at a young age are more likely to develop more aggressive cancers.  Despite estrogen's link with an increased risk of developing mammary tumors, the researchers found that higher serum estrogen levels also seemed to help dogs avoid some of the riskiest aspects of their disease. Unexpectedly, when dogs were spayed at the same time their tumors were removed, those with estrogen receptor-positive tumors that had higher serum estrogen took longer to develop metastatic disease and survived longer than dogs with lower estrogen levels, confirming that these tumors depended on estrogen for progression.  Karin U. Sorenmo, a veterinary oncologist at Penn Vet and senior author on the study, speculates that, in these cases, estrogen's action may be nuanced. "It drives the cancer, but it also seems to control or modulate it, reining it in," she says, because most dogs with high serum estrogen levels had lower-grade and estrogen receptor-positive tumors, rendering them susceptible to hormonal deprivation by spaying.  The protective role of estrogen was also surprisingly pronounced in dogs with estrogen-receptor negative mammary tumors. In these higher-risk cancers, high serum estrogen was associated with delayed or absent metastasis. Complementing these findings and supporting a potential broader, tumor receptor-independent anti-cancer effect driven by estrogen, dogs with low serum estrogen had a significantly increased risk for developing other non-mammary aggressive fatal tumors, such as hemangiosarcoma, during their follow-up after mammary tumor surgery.

     The reproductive organs are not alone in producing sex hormones. The endocrine glands also produce small amounts.  When the sex organs are removed, the animals’ body will attempt to compensate for the loss by enlisting the endocrine system, namely the adrenal glands, to work harder to stimulate production.  It makes sense that we would see issues plaguing this body system from the added relentless stress.


     Current scientific study has established that sex hormones profoundly affect growth and development, the immune system, susceptibility to major diseases including metabolic and endocrine diseases and cancer.  The list of diseases and disorders that can be linked to the loss of sex hormones include:  osteosarcoma (bone cancer), cruciate ligament tears and ruptures, hip dysplasia, elbow dysplasia, physeal (long bone) fractures in male cats, hemangiosarcoma  (cancer of the heart or spleen), lymphosarcoma (cancer of lymphatic glands and tissue), prostate cancer, urinary tract cancer, urinary tract blockage in male cats, mast cell tumors, cushing’s disease, atypical cushing’s, diabetes, incontinence in female dogs, allergies, alopecia (hair loss), obesity, negative vaccine reactions, excessive fear of people or dogs, fear of noises, separation anxiety, touch sensitivity, cognitive impairment and aggression.  You read that right!  Dogs that are spayed and neutered can be more aggressive, especially to their own family.  Two large scale studies involving nearly 16,000 dogs have established this.  One was conducted in 2006 by Deborah Duffy and James Serpell both at the School of Veterinary Medicine at the University of Pennsylvania, the other a masters’ thesis at Hunter College in New York submitted by Parvene Farhoody in 2010.

     Another study by the Gerald P. Murphy Cancer Foundation, published in 2009, established a link between the age at which female Rottweilers were spayed and how long they lived.  The normal life span of a female Rotti is considered to be about 9 years but some are living to 13 years or more.  The study showed that females live longer than males but spaying before age 5 removed that longevity advantage.  Females that kept their ovaries until at least 6 years of age were 4 times more likely to be long lived compared to those who were spayed at a younger age.

     The majority of studies being done involve dogs, but it would stand to reason that cats would be affected by early spay and neuter also.  Certainly there need to be more comprehensive studies to assess the impact on our felines.  It is suspected that loss of those hormones before maturity leads to increased risk of urinary blockage in male cats due to the ureter becoming hair thin following neuter.  Cats are often neutered and spayed before sexual maturity because of the undesirable behaviour displayed especially by males.  There was a small study in published in 2002 that found a link between early neuter in male cats and spontaneous physeal (long bone) fractures due to delayed physeal growth plate closure.  Thus far however, it appears our canine companions are much more negatively affected by early spay and neuter than are kitties.

     There are health issues that we know can be avoided almost completely by spaying and neutering. They are pyometra (infection of the uterus) in females and benign prostatic hypertrophy (enlarged prostate) in males.

     What can you do? 

     Let us start by saying that each animal and each pet parent is an individual and the decision on if and when to spay and neuter will be dependent on the animals breed, nature or personality, your lifestyle and the commitment you can make to training and responsibility.  For responsible pet parents, where there is no risk of their sexually mature dog or cat either accidentally impregnating another or getting pregnant, the following would be recommended:

     If you plan on sterilizing your puppy, wait as long as you can.  For small breeds wait until they are at least a year old, medium sized dogs 1.5 years, large dogs 2 – 2.5 years and giant breeds at least 3 years.  If and when you have the procedure done, seek out a veterinarian who will do for females either a tubal ligation or an ovary sparing spay where the uterus is removed but the ovaries are retained.  For males, a vasectomy would be the preferred procedure.

     If you have a kitten and you can do so responsibly, wait as long as you can.  Male cats will start exhibiting those off putting behaviors between 7 and 10 months of age.  Males can become more aggressive and can also start urine spraying and marking.  Females show clear signs of being in heat with dramatic vocalization and amorous behaviour.  Unlike female canines, who generally start their first heat between 7 and 12 months (lasting about 3 weeks) and then have, on average, a heat cycle every 6 months, your female feline, once she goes into heat, can mate and produce offspring at any time, as she can ovulate spontaneously when there is male contact.  If you have a male and female cat both intact living together you will need to get at least one of them spayed or neutered younger to avoid a litter and keep them separated from 4 months of age until one of them is “fixed”.  A male cat has the potential of doing the deed at 5 months of age, possibly younger, and a female can potentially go into season between 5 and 6 months of age, so better safe than sorry!  Kitties who are looking for some action will most definitely try to escape out of the house to seek out a mate.  I cannot stress enough the importance of being responsible so there is no way of ending up with an unwanted litter.

     If you have a dog or a cat that was spayed or neutered either before maturity or after, you can rebalance their hormones by working with a holistic veterinarian or qualified practitioner to get their hormone levels tested and then incorporate natural sources of the hormones they have lost, or by using actual hormone replacement therapy.  I am including a link to the Healthy and Happy Dog website which is an invaluable resource.

     A very effective way to help rebalance the hormones is to give the homeopathic remedy in 30C potency, made from the organs they have lost:  Canine Teste, Feline Teste, Canine Ovary or Feline Ovary, to help their body better compensate for the loss of those hormones, protect against the diseases and disorders for which they are at higher risk and bring them back into better balance physically and mentally.  These remedies can also help those animals who are already suffering from loss of hormone related issues.  For more information please contact me through the contact page. 

References and links:

Jasper & Topaz
Sage & Merlin
Easton & Jade
Easton & I
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