Countering the Effects of Neuter


If your dog has already been neutered, there are some things you can do to help him live the healthiest and happiest life possible. The key to keeping your dog healthy is to assess and confirm the point in time that his adrenal glands are no longer able to compensate for the loss of his testes and the hormones they produce (adrenal insufficiency).

For many dogs, after they are neutered, 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, 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 neutered after his 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, he probably won’t be afflicted with the worst of the orthopedic problems we have detailed on this website. However, no neutered dog is immune to the hormonal chaos neuter creates – the difference is the timing.

If your dog does not experience orthopedic problems, the first warning signs of adrenal insufficiency may be a general lethargy and perhaps some confusion.55 Don’t assume it’s inevitable because he is getting older. Have your dog’s thyroid gland hormones and adrenal/sex hormones tested. If the thyroid gland hormones are low, most veterinarians will be very comfortable prescribing thyroid hormone supplements. However, if the adrenal gland function (and sex hormone level) is also not normal, it may not be in your dog’s best interest to supplement the thyroid hormone alone. In case studies where adrenal hormones are also abnormal, adrenal hormone replacement therapy returned the thyroid levels to normal without the need for thyroid hormone replacement.105

This research is important for two reasons: first it exemplifies the complexities of the thyroadrenal interactions. Second, it proves the point that recovery from the endocrine disruption of neutering 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 behavior problem(s) may be a barometer as to the necessity for testosterone replacement. And, replacement of testosterone may resolve the observed behavior problem(s). However, the overriding reason for hormone replacement is ultimately to repair the more systemic damage done to your dog’s immune response by castration.HAHD_hormone_imbalance For practical purposes, we find hormone “re-balancing” may be the better term to use. Some hormones will be in excess, while others may be deficient. The actual combination of hormones required, and their corresponding quantities, in order to repair the immune response and ideally prevent the development of cancer/Cushings or other endocrine related diseases (e.g., diabetes), are much more difficult to ascertain with any degree of certainty. Please refer to the Diseases Overview page on this website for a more in-depth explanation of the overarching effects of spay/neuter.

If your dog was neutered before his growth plates closed, the first health related problems you see may be orthopedic, and they may occur at a younger age – often 4-5 years of 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 his knee(s). If just one ligament is torn, the orthopedic surgeon will not insist the second one will tear. 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 and adrenal hormones after he has recovered from the surgery. This is a pivotal point. The stress of a surgery is often the tipping point for the adrenal glands’ ability to compensate and produce the normal level of sex steroids your dog requires. The thyroid may be a problem as well, but it may resolve after correction of the other hormones as described above.

In males, it is practically impossible to address their hormone imbalance without a hormone panel. It is quite likely your dog will be deficient in testosterone and no veterinarian would give your male dog testosterone supplements unless there is a documented deficiency. Our internal medicine specialist was unwilling to give Billy testosterone even though we documented a complete absence of testosterone. Our primary care veterinarian was kind enough to help us, but it was not without reservations. He feared Billy would become aggressive after receiving testosterone. In fact, testosterone had the opposite effect – it made Billy much less fearful. For dogs who suffer from leash aggression, or fear aggression (see the behavioral effects of neuter), testosterone supplementation can make them less aggressive.

Male dogs may also be deficient in progesterone. For male dogs who exhibit signs of agitation (sometimes to the point of panic), generalized anxiety and/or fear of new people, dogs or new situations, they might very well be deficient in testosterone as well as progesterone. We know that progesterone has a strong effect on the serotonin, norepinephrine, dopamine and endorphine receptor sites in the brain, which are involved in mood regulation. Progesterone can also be supplemented by injection through your veterinarian.

If your veterinarian does not feel comfortable providing progesterone by injection; SAMe is a supplement which, in dogs, is reputed to mimic the activity of progesterone in their brain. SAMe affects mood by helping to increase the availability of neurotransmitters, such as serotonin and dopamine (which are attributed to feelings of emotional wellbeing). SAMe is reported to also increase the number of neurotransmitter receptors. There are SAMe supplements available that have been formulated specifically for dogs. Scientific research also supports SAMe’s ability to promote liver health and joint comfort – key components to physical health and wellbeing.

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 our vet. Denamarin was beneficial to his liver, somewhat helpful for his joints, and extremely helpful for his fear and anxiety. If your dog has a deficiency in testosterone as well as progesterone, SAMe supplements or even injections of progesterone might help, but their activity could be overshadowed by the absence of testosterone.

Males may also have too much estradiol, also termed “hyperestrinism“. Estradiol is the most powerful form of estrogen and is generally predominant in females, not males. If the estradiol is excessive, but moderately so, currently the veterinary “experts” who provide the hormone panels and treatment recommendations to your veterinarian will recommend supplementation with a moderate aromatase inhibitor (e.g., melatonin and/or lignans like flaxseed). However, in our opinion, this is not a prudent recommendation.  We would refer you to our page on Hormones and the Endocrine System under the Diseases section so that you might see the unintended consequences of melatonin supplementation.

If there is a gross excess of estradiol, as Billy experienced, you will have to ask your veterinarian to prescribe a strong aromatase inhibitor to block the production of estradiol. At our specific request, our internal medicine specialist prescribed a very strong aromatase inhibitor, i.e., anastrozole, for Billy. Anastrozole has been tested extensively in dogs (with the intent of evaluating its safety for humans) and is regarded as safe to use in canines.

The most concrete recommendation we can offer 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 2005 34 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.

Additionally, in 2011 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. However, the task force changed the previous recommendation for distemper, parvovirus and adenovirus from once a year to a frequency of once every 3 years. The task force also acknowledged in the updated guidelines that immunity lasts at least 5 years for distemper and parvovirus, and at least 7 years for adenovirus. In light of the greater risk of adverse reaction in spayed dogs, we do not see the wisdom of vaccinating more often than is absolutely necessary. Therefore, we recommend a vaccination frequency of once every 5 years for distemper or parvovirus, and once every 7 years for adenovirus.

We are not advocating the avoidance of vaccinations. We see this as an opportunity for shared decision making 63 with your veterinarian to provide your dog with vaccinations on a schedule that is best for your dog.  Best practice would be just one vaccination on any given day, with a reasonable period of time between vaccinations. This precautionary approach becomes even more important when your dog is small.