Countering the Effects of Spay


If your dog has already been spayed, there are some things you can do to help her live the healthiest and happiest life possible. The best chance you have to keep your dog healthy is to assess and confirm the point in time that her adrenal glands are no longer able to compensate for the loss of her ovaries and the hormones they produce.

For some dogs, after they are spayed, they appear to be okay, i.e., no major health problems, no behavioral issues. If they live in a happy environment with adequate attention and exercise (we will discuss the significance of these in more detail later), they may reach 7 or 8 years of age before you notice any problems. If that’s the case, thank your lucky stars. Your dog was spayed after her bony growth plates had closed. The bony plates generally close between 4 and 18 months of age, depending on the individual dog. If this is the case for your dog, she probably won’t be afflicted with the worst of the orthopedic problems we have detailed on this web site. However, no spayed dog is immune to the hormonal chaos spay creates – the difference is the timing.

There are a significant number of female dogs who experience behavioral changes after spay, and for some the changes are dramatic and immediate. At this point in time, most veterinarians are recommending obedience training and/or behavior modification and if these are not satisfactory, they might prescribe antidepressant medications. From our perspective, this approach is counterproductive or, at best, merely ineffective. To correct a problem you must first accurately identify the underlying cause of the problem. The negative changes in your dog’s behavior are the product of structural and functional changes in their brain due to a lack of sex hormones. The ideal remedy is to balance their hormones and hopefully achieve the hormone levels of an intact dog. In addition to our recommendations on this page please see our sections entitled “Behavioral Effects of Spay” and “The Stress Response System” for a more detailed explanation of the changes in the canine brain and further discussion of remedies.

Balancing hormones offers the best opportunity to enhance physical health as well as restore the balance of neurochemicals (i.e. serotonin, norepinephrine, dopamine, etc.) in the brain. Balancing hormones is complicated and when behavior is still problematic after hormone balancing (or if hormone balancing is not available), we favor supplementation with SAMe and perhaps DHEA rather than antidepressants. Antidepressants have significant side effects and are not designed to address excess norepinephrine generally found in the brain of symptomatic, spayed dogs.

If your dog does not experience orthopedic or behavioral problems, the first warning sign that her adrenal glands can no longer compensate for the sex hormones lost from spay may be incontinence. If your dog is suffering from some level of incontinence, the most likely culprit is a low level of estrogen. It is so common as to be described in the veterinary literature as “spay incontinence“. Some veterinarians may prescribe phenylpropanolamine (PPA), which can sometimes successfully resolve the symptoms, however there are risks with the use of this compound, and the underlying hormonal deficiency still persists. Estrogen replacement therapy is another option, but should not be undertaken without a hormone panel to confirm if estrogen and other hormones like progesterone and testosterone are also deficient. It is extremely important for females to include DHEA in the panel.

There is an opportunity to enhance the female dog’s ability to produce estrogen even after ovariohysterectomy (spay). Dehydroepiandrosterone (DHEA) is a hormone that can be made into estrogen or testosterone and it is mainly secreted by the adrenal glands in females. The ovaries’ contribution to circulating DHEA appears to be limited, although in intact females it may partially compensate for an age-related decrease in adrenal hormonal secretion.101 Spayed females don’t have the ovaries to fall back on when the adrenal glands are overwhelmed by stress, the additional demands of hormone production due to spaying, and age-related decrease in secretion. If the hormone panel shows a deficiency in estrogen and DHEA, supplementation with DHEA103 could allow additional estrogen production in the brain or fatty tissue.102 Because the additional estrogen will be naturally produced within your dog’s body, you will have no concerns as to whether the estrogen will be synthetic, natural, or bioidentical, as is the case in traditional hormone replacement therapy. If the DHEA supplement leads to additional estrogen production, the spay incontinence will generally resolve.

DHEA is inexpensive and can be purchased over the counter at local pharmacies or online pharmacies. It is preferable to use a micronized formulation. There are no exact dosing recommendations we can find, however, studies do tend to give a range of dosing that appears to be safe – 5 to 25 mg. orally, each morning.

Another set of symptoms that are an indicator of adrenal insufficiency may be general lethargy and perhaps some confusion.55 Don’t assume it’s inevitable because she is getting older. Many spayed dogs as they age exhibit the behavioral characteristics of early Alzheimer’s patients which would include confusion, mood disorders, aggression, and depression (often interpreted as lethargy). For dogs affected in this manner, DHEA supplementation may be highly beneficial (see our Stress Response System page for a more complete explanation). The first step is to have your dog’s thyroid gland hormones and adrenal/sex hormones (i.e., estrogen, testosterone, progesterone and DHEA) tested for imbalance. If the thyroid gland hormones are low, most veterinarians should be very comfortable prescribing thyroid hormone supplements. However, if any of the adrenal and/or sex hormones are also low, it may not be in your dog’s best interest to supplement the thyroid hormone alone. In case studies where adrenal/sex hormones are also abnormal, adrenal/sex hormone replacement therapy returned the thyroid levels to normal without the need for thyroid hormone replacement.105

The aforementioned research is important for two reasons:

  1.  It exemplifies the complexities of the thyroadrenal interactions.
  2.  It proves the point that recovery from the endocrine disruption of spay is not straightforward; endocrine (hormonal) interactions within your dog are a complex web of inter-related feedback mechanisms.

As in the example above, simply adding in a hormone which is low may not solve the problem, but actually make it worse. On the other hand, your dog’s incontinence and/or behavior problem(s) may be a barometer as to the necessity for hormone replacement. And, replacement of a single hormone may resolve the observed incontinence and/or behavior problem(s).

Another significant reason for hormone replacement is to counter the more systemic damage done to your dog’s endocrine system by spay.HAHD_hormone_imbalance In female dogs we find the presence of estrogen/progesterone in appropriate amounts has a statistically significant protective function in preventing three serious, deadly cancers found in dogs. These cancers would be hemangiosarcoma, lymphosarcoma (lymphoma) and mast cell tumor (see our cancer page for a more lengthy explanation). The actual mechanism whereby estrogen and possibly progesterone exert their protective influence is not understood, but the data is compelling and cannot be ignored.

With respect to cancer, the argument is often made that spay minimizes the risk of mammary cancer. A recent meta-analysis of the evidence has shown the research supporting this oft-repeated argument is seriously flawed and should not be relied upon. We do suggest that female dog guardians, regardless of whether your dog is spayed or not, perform manual exams of their dogs chest area routinely, and ask that their vet evaluate their dog for mammary cancer at each vet visit. As in humans, routine exams can detect mammary (breast) cancer at an early stage where it is more successfully treated.

With respect to hormone replacement therapy, we find hormone “re-balancing” may be the better term to use. Some hormones may be in excess, while others may be deficient. Identifying the hormone levels, and supplementing/reducing their corresponding quantities to physiologically ideal ranges, is difficult, but necessary. The Endocrine Society’s latest Scientific Statement on the subject of endocrine disruption explains:

“…levels of any hormone must be within a physiologically relevant range to be most effective. Excursions outside of that range to superphysiological (elevated) or subphysiological (depressed) levels for any extended period nearly always result in dysfunction or disease.” 176

This common sense concept explains why you need to balance hormones to the levels of a normal, intact dog. Further, the veterinary community’s policy of setting alternate normal ranges of hormones for spayed dogs illustrates their complete failure to respect or understand endocrine and metabolic function.

Restoring optimal hormone balance to your dog’s endocrine system can help prevent the development of cancer, Cushings, diabetes, and other endocrine related diseases. Further, normalizing hormone levels will enhance her ability to respond to stress and bolster her immune system function. Please refer to the Diseases – Overview  page and “The Stress Response System” page on this website for a more in-depth explanation of the overarching effects of spay/neuter on your dog’s ability to respond to stress. Additionally, immunonutrition therapy is emerging as an effective adjunct to hormone balancing in dogs. Immunonutrition therapy is a discipline wherein the goal is to enhance immune system activity by including specific nutrients in the diet. Please refer to our Cancer page for more details on Billy’s experience with immunonutrition therapy.

If your dog was spayed before her growth plates closed, the first health related problems you see may be orthopedic, and they may occur at a young age. If your dog struggles to sit and get up from a sitting position and is moving poorly in general (see Billy’s videos on his timeline), your dog may have torn the cranial cruciate ligament in her knee(s). If just one knee’s ligament is torn, the orthopedic surgeon most likely will not insist the other knee’s ligament will tear as well. However, based upon our current knowledge as to the cause, it’s pretty clear you can expect the second knee to have the identical problem. Similarly, in the case of elbow and hip dysplasia, you can expect the dysplasia to be bilateral.

If you proceed with surgery for any of the aforementioned orthopedic issues, you should test your dog’s thyroid, sex and adrenal hormones after it appears she has fully recovered from the surgery (this will vary for every dog). You want to be sure you have allowed adequate time for the adrenal gland to recover from the stress of surgery before testing. You will be the best judge as to whether your dog has recovered to the level of strength and activity that she possessed prior to the injury. This is a pivotal point because outward appearance would indicate your dog has healed from her surgery. However, the initial damage spay inflicted upon your dog’s brain and endocrine system likely will not allow normal immune or metabolic response to the stress of a subsequent surgery. The stress of a surgery may stimulate your dog’s adrenal glands to produce cortisol, so much cortisol that the adrenal gland is no longer able to produce the level of sex hormones your dog requires. Lack of sex hormones will again cause functional and possibly structural changes in your dog’s brain as well as dysregulation of the endocrine system. This will predispose your dog to metabolic disease (e.g. diabetes) as well as immune-mediated disease (e.g. cancer). The thyroid may be a problem as well, but it may resolve after hormone re-balancing as described above.

There is also emerging research which has found estrogen may be protective against brain ageing and brain tumour growth in dogs. A direct comparison of intact female dogs and spayed female dogs found the lower estrogen levels of spayed dogs increased the relative risk of brain tumours 11-fold. 175

There are simple blood tests to determine levels of estradiol, testosterone, thyroid, progesterone, and DHEA. We do want people to get tangible evidence of hormonal imbalance before making significant changes through supplementation. You should also attempt to employ shared decision making63 to make some improvements to your dog’s hormonal balance that you and your veterinarian can feel comfortable with.

For female dogs who exhibit signs of agitation (sometimes to the point of panic), generalized anxiety, fear of new people, dogs or new situations, they may be deficient in estradiol as well as progesterone. Research in humans provides us some very strong evidence as to what the removal/imbalance of female hormones can do with respect to brain chemistry and its effects upon personality. Consider the findings of this systematic review104 :

“…that responses to estradiol are present in brain regions that are not directly associated with reproductive success but are important for learning, memory, emotional responding, mood, and sensorimotor control…there is substantial evidence for the therapeutic benefits of estrogens in the brain.”

In fact, among endocrine specialists, it is recognized that the broader aim of raising awareness of the mental health implications of women’s gynecological conditions has been neglected. In one section of this linked article there is a discussion of mood disorders associated with “Dysregulation of the HPA Axis”, which is a common problem among spayed dogs. See our “Hormones and the Endocrine System” and “The Stress Response System” pages for more information on the HPA Axis.

If testing reveals a deficiency of DHEA, estradiol and/or progesterone, you should be able to supplement under the supervision of your veterinarian. Another option may be a supplement humans often take, SAMe, for mood regulation.  There is evidence that SAMe can affect neurotransmitters as does a proper balance of estradiol and progesterone in a female dog’s brain. The research best supports the concept that SAMe helps neutralize norepinephrine in the brain. Norepinephrine is found in excess in the brains of dogs unable to appropriately respond to stress. An alternate theory is that SAMe acts by  helping to increase the availability of neurotransmitters, such as serotonin and dopamine (which are attributed to feelings of emotional well-being), as well as increasing the number of neurotransmitter receptors. There are SAMe supplements available that have been formulated specifically for dogs. A general dosage guideline is 10mg. of SAMe per pound daily, although some manufacturers provide tablets dosed for a range of body weights. Scientific research also supports SAMe’s ability to promote liver health and joint comfort – key components to physical health and wellbeing. SAMe works best when given in the AM on an empty stomach at least 1 hour before a meal. Research has reported SAMe’s side effects to be negligible.

Sometimes when a dog has elevated liver enzymes, a combination of SAMe and silybin (milk thistle)17 is recommended. These are available as generics formulated for dogs or in combination as Denamarin. Denamarin does not require a prescription and was recommended for Billy by his vet and was beneficial to his liver, somewhat helpful for his joints, and extremely helpful for his fear and anxiety. An important side note regarding liver enzymes – within Billy’s liver enzymes, all the abnormalities could be explained except one – his GGT level. We specifically asked our vets what could account for this elevated GGT. The vets had no answers. Years later, in our research, we found that in humans, elevated GGT is a harbinger of a patient developing Type 2 diabetes.94

Earlier on this page, we mentioned the importance of adequate attention and exercise for your dog, especially if she is spayed. There is scientific evidence to support these “common sense” suggestions. There are neurochemicals found in the brains of dogs and humans which promote feelings of happiness or bliss. In light of all the negative effects of spay on the brain, an activity that enhances brain chemistry may make a significant difference in your dog’s quality of life.

As is the case with humans who run frequently, researchers have discovered that dogs also experience a “runner’s high”  The “high” comes from the release of endocannabinoids (eCBs) during moderate to high intensity exercise. Walking, such as on a leash, is not sufficient intensity of exercise to stimulate release of eCBs.166 Our dog Billy was run close to 6 miles daily at the beach near our home, and we found it was extremely helpful in alleviating his anxiety. Not everyone can run far enough or fast enough to give their dog adequate exercise to provoke the release of eCBs. But certainly most anyone can play fetch with their dog. Some dog guardians comment that their dog  seems obsessed with their ball/frisbee. Perhaps their dog is simply addicted to the “high” running after the ball/frisbee provides them.

We also suggest it is important to give your dog adequate attention. Certain neurochemicals known to provide psychological benefits are generated in humans when they have positive interactions with other species. Consistent with the “Canine-Human Connection“, in 2003 a study was conducted to see if the same neurochemicals and psychological benefits would be present in dogs. The study’s results confirmed that concentrations of beta-endorphin, oxytocin, prolactin, beta-phenylethylamine and dopamine increased in both humans and dogs through their positive interaction.167 In 2010, at the 12th International Conference of Human-Animal Interactions, scientists presented their findings confirming that friendly human-dog interaction releases oxytocin in both human and dog.


The most concrete recommendation we can offer that can protect your dog from the adverse effects of spay/neuter is with respect to vaccinations. Because spay/neuter has an adverse effect on the immune system, guardians of spayed/neutered dogs must be cautious with respect to vaccinations. A study was conducted in 200534 to analyze adverse events diagnosed within three days of vaccine administration in dogs. The vaccine-associated adverse events included nonspecific vaccine reaction, and allergic reactions varying in severity from a rash or hives all the way to anaphylaxis (which can block breathing and be fatal). The study found danger of an adverse reaction goes up substantially when a dog is spayed or neutered, and the less a dog weighs, the more likely they are to experience an adverse reaction. Further, the risk increases substantially with each additional vaccination given at one time.

Therefore, best practice would be just one vaccination of any type on any given day, with a reasonable period of time between vaccinations. This precautionary approach becomes even more important when your dog is small.

Additionally, in 2017 the American Animal Hospital Association (AAHA) canine vaccination task force updated their vaccination guidelines. Rabies vaccinations remain effective for a period of 1 to 3 years, depending upon your previous method of vaccination. In 2011 the task force changed the previous recommendation for distemper, parvovirus and adenovirus vaccination from once a year to a frequency of once every 3 years. The task force also acknowledged in the 2011 guidelines that immunity lasts at least 5 years for distemper and parvovirus, and at least 7 years for adenovirus. In 2017 there are no notable changes to these core vaccine recommendations (rabies, distemper, parvovirus and adenovirus), except that the parainfluenza virus is now considered an optional core vaccine according to the AAHA. In these 2017 vaccination guidelines, for the first time, the AAHA acknowledges that titer tests are useful in determining dogs’ immunity to distemper, parvovirus, and adenovirus. A titer test is a blood test designed to evaluate immunity, so if the titer test shows immunity to one of these core vaccines, you can safely avoid additional vaccination.

The problem we had was in researching the process of titering we could not find any solid guidelines. It seemed that the effectiveness of the process of titering required a vet experienced in the process of interpretation to get it right. Not everyone has access to a vet with this skill set. We did, however, find a simple solution to this problem as provided in an article by Dr. Karen Becker (her interview with Dr. Valente about spay/neuter is on this website). Dr. Becker states:

“I prefer to run IFA (immunofluorescence antibody) titer tests for parvo and distemper because they give a clear-cut answer, either ‘yes the animal is protected,’ or ‘no the animal is not protected.’ Because most veterinary schools are still not adequately educating their students about titer test interpretation, this removes any question of whether the pet is protected or not.”

The 2017 updated vaccination guidelines also discuss a group of new vaccinations which are non-core (strictly optional). These would include bordetella (kennel cough), leptospira, Borrelia burgdorferi (Lyme), canine influenza viruses H3N8 and H3N2 and Crotalus atrox (western diamond rattlesnake). Common sense would dictate a pet guardian only consider these immunizations if they believe their dog’s environment provides substantial risk of exposure to one of these pathogens, and their dog is healthy.

We are not advocating the avoidance of vaccinations. We see this as an opportunity for shared decision making63 with your veterinarian to provide your dog with vaccinations on a schedule that is best for your dog. An article by Dr. Karen Becker regarding these new 2017 vaccination guidelines may give you some information to consider when discussing your dog’s vaccination schedule with your vet. For example, when Billy was an uncontrolled diabetic and had hormone imbalance we were trying to address, our primary care vet agreed with our decision to avoid the core vaccines.