A dog’s endocrine system is composed by several glands that are meant to produce hormones which are then transmitted through the bloodstream where they have several effects on the dog’s body and mind.
The hormone testosterone, in particular, is secreted by the male dog’s testes and is known for producing several physiological and behavioral effects. So today let’s discover more about the effects testosterone has on dog behavior, and surprisingly, on female dogs as well!
Testosterone Starts in the Womb…
Testosterone generally flows at a pretty steady pace during an intact (not neutered) male dog’s life, but there are two specific times during a dog’s lifetime during which this hormone significantly impacts the dog’s brain. The first time likely takes place very early in development, when the puppy is still in the womb.
During this time, testosterone is spread from the amniotic membrane and through the blood flowing from the uterus until it reaches the pup’s brain. Once in the dog’s brain, it’s as if testosterone turns on an imaginary switch that prompts the brain to undergo anatomical changes and turns on the “masculine” button.
Also, it appears that the hormone creates a predisposition for hard-wired behaviors in male dogs that may remain dormant until the next testosterone surge switches on later in life.
“In the uterus, testosterone can diffuse through the amniotic membrane and through uterine blood flow. Once it reaches the male dog’s brain, it brings about gender-specific structural changes that then relate to later development of sex-typical behaviors… These changes masculinize the male brain structure.” James O’ Heare
And May Affect Female Dogs Too!
Wait, what does testosterone have to do with female dogs? Isn’t testosterone exclusively a male dog hormone? While testosterone is associated with maleness and typical male dogs behaviors, there are chances it may affect female dogs too. How is that? Well, here’s an insight into what may be happening
The phenomenon is known as androgenization, and it takes place in the uterus (yup in the womb). What’s likely to trigger this is a matter of the position of female dogs in the mother dog’s womb. If a female dog happens to be positioned between two males, there are chances her brain may be influenced (masculinized) courtesy of the diffusion of testosterone through the amniotic membrane, explains James O’Heare in the book “Aggressive Behavior in Dogs: A Comprehensive Technical Manual for Professionals.”
“Strong experimental evidence suggests that female embryos situated between males in the uterus are more likely to develop male-like aggressive tendencies and scent-marking patterns than are counterparts otherwise situated. Some suggestive evidence regarding the effects of perinatal androgenization of female dogs has been reported by Coppola. ~Steven Lindsay
But it’s During Puberty That Dogs Get the Big Surge.
Back to male dogs, the second surge of testosterone occurs when the male dog reaches puberty. According to a study by Pathirana IN et al 2012, the levels of testosterone in dogs starts to rise in dogs just prior to puberty, around the ages of 4 to 6 months old, and then reaches a surge once the dog reaches puberty, generally when the dog is an adolescent between 6 and 12 months. Afterwards, testosterone levels maintain a state of little or no change, generally from when the dog is one to five years old and then those levels starts declining when the dog becomes senior.
As Expected, Testosterone Triggers Male Behaviors…
During the puberty surge in testosterone, there is often an increase in sexually dimorphic behaviors, basically behaviors that are mostly seen in male dogs. This is often when owners of intact dogs start noticing behaviors such as roaming in search of a mate, lifting the leg to urine mark, mounting, and competition with other male dogs. These behaviors are often what causes dog owners to consider neutering their dogs.
But there Are Chances Neutering May Reduce Them.
When a male dog is neutered (castration) the removal of a dog’s testes causes the production of testosterone to come to a halt. With testosterone levels reduced, there is often a marked decrease in behaviors driven by hormones such as urine marking, roaming in search of a mate and competition with other male dogs.
For those looking for statistics, a study has found that after neutering, roaming behavior decreased 90 percent, aggression between male dogs decreased 62 percent, urine marking decreased 50 percent and mounting decreased 80 percent.
However, there’s not much good news for dog owners expecting to see their male dogs calm down and settle after castration. That’s likely never going to happen any time soon because excitability and unruly behaviors are seldom driven by testosterone, explains Mat Ward, a Certificated Clinical Animal Behaviorist. On top of that, owners must consider that, despite the statistics appearing promising, neutering does not necessarily have total control over stopping sexually dimorphic behaviors.
But a New Study Says Neutering Won’t Likely Do Much to Stop Aggression.
Many people consider neutering their dogs because they feel that testosterone plays a role in aggression, but how true is that? For many years, and in many cases still as of today, the advice to neuter a dog is given out by dog trainers and veterinarians when presented with an intact male dog showing signs of aggressive behavior.
Neutering therefore has been commonly recommended throughout the years and has been a strong selling point to solve aggression problems, but it’s not that easy to justify the common notion that neutering is a cure-all. So does neutering stop dog aggression?
Karen Overall in her book Clinical behavioral medicine for small animals, talks about testosterone acting as a behavior modulator causing intact dogs to react more quickly, more intensely and for a longer period of time compared to neutered dogs. However, she also warns that when it comes to aggression, neutering a dog may lower the tendency to exhibit aggression towards other dogs (which can be hormonally driven); but there’s not enough data to show the effects neutering may have on other specific types of aggressive behaviors.
Indeed, in most cases, neutering won’t fix dog behavior problems such as territorial or fear-induced aggression,resource guarding or food aggression. This is likely because there are several other factors at play other than hormones when dogs behave aggressively such as the impact of the environment in which the dog is raised, the dog’s genetic makeup, the dog’s history, and so forth. However, it’s also true that testosterone has been known to affect anxiety behaviors; for instance, among humans men who fail to produce enough testosterone tend to be more likely to suffer from anxiety and depression and testosterone treatments tend to alleviate these.
Interestingly, for those looking for data, a study using a large sample of dogs conducted by Parvene Farhoody and M. Christine Zink, found strong correlations between neutering and aggression, with neutered dogs exhibiting high levels of fear, anxiety and excitability, regardless of when the dog was neutered. And this is quite impressive data, especially considering the increase in aggressive behaviors seen in the past years in our companion dogs and considering the fact that a large percentage of aggressive behavior in dogs stems from fear, which coincidentally correlates with the modern trend of neutering dogs.
” Our data showed that the behavior of neutered dogs was significantly different from that of intact dogs in ways that contradict the prevailing view. Among the findings, neutered dogs were more aggressive, fearful, excitable, and less trainable than intact dogs. “~Parvene Farhoody & M. Christine Zink
References:
- Hopkins SG, Schubert TA, Hart BL. Castration of adult male dogs: effects on roaming, aggression, urine marking, and mounting. J Am Vet Med Assoc 1976;168:1108–1110.
- Overall KL. Clinical behavioral medicine for small animals. St Louis: Mosby Year Book Inc, 1997.
- Cooley DM, Beranek BC, Schlittler DL, et al. Endogenous gonadal hormone exposure and bone sarcoma risk. Canc Epidemiol Biomark Prev 2002;11:1434-1440.
- Howe LM, Slater MR, Boothe HW, et al. Long-term outcome of gonadectomy performed at an early age or traditional age in dogs. J Amer Vet Med Assoc 2001;218:217-221.
- Pathirana IN et al (2012) Plasma insulin-like peptide 3 and testosterone concentrations in male dogs: changes with age and effects of cryptorchidism. Theriogenology77(3):550-557
- Farhoody, P. Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs. Smmary of findings detailed in Masters thesis submitted to and accepted by Hunter College in May 2010.
- Hart, B. L., & Eckstein, R. A. (1997). The role of gonadal hormones in the occurrence of objectionable behaviours in dogs and cats. Applied Animal Behaviour Science, 52, 331-344.
- Aggressive Behavior in Dogs: A Comprehensive Technical Manual for Professionals, James O’Heare, Dogwise Ebooks; 2 edition (April 17, 2014)
Photo Credits:
A Greeting Behavior
A Sign of Apology
Medical Conditions
So what is a dog’s topline? A dog’s topline is the profile line that goes from the dog’s shoulders to the base of the tail, tells us Veterinary Sports Medicine and Rehabilitation specialist Dr.
The topline can be straight in some dog breeds. So if you were drawing these dog breeds that profile line would be for the most part straight from the shoulder area to the tail.

The topline can be sloped in some dog breeds. So if you were drawing these dogs breeds, the profile line would slope towards the loin area, a bit like a mountain slope. Some people refer to this tendency as sagging or roaching back. Dogs with a sloping topline tend to have more angulation in the rear legs which results in a lowered rear.



Hi there, it’s your dog’s chest talking! I am happy you are interested in hearing my story. I have a lot of little pieces of information to share with you. First, let’s start with my name. I also go by the medical name thorax, which derives from the ancient Greek word thorakos meaning “breastplate.” You might also be interested in learning more about your dog’s thoracic cavity (chest cavity) and thoracic wall (chest wall). Where am I located? I am right between your dog’s neck and his abdomen.
While I am overall pretty sturdy, I can only take so much. Traumatic injuries to the chest wall are unfortunately not uncommon in dogs. They may stem from being hit by car, kicked by a horse or a stab/impalement wound such as running into a branch, but in many cases the trauma to the chest area area in animals is due to bite wounds sustained by small dog breeds.

Veterinary behaviorist Karen Overall in the book “Manual of Clinical Behavioral Medicine for Dogs and Cats” defines the perpendicular T posture assumed by a dog interacting with another dog as an interaction that is involving social challenge. When a dog postures in this way, he gets in the other dog’s way and limits the other dog’s room for maneuver. Dr. Overall lists the “T posture” as an agonistic behavior that is likely to have an aggressive component.
Is standing over in dogs a sign of dominance? Is the dog standing over the other dog dominant? Many people wonder about this and sometimes heated discussions arise around the usage of the term “dominance.”
Dog owners often describe their dogs as if biting at some imaginary fly hovering in the air, but in reality there are no bugs around. For this reason, this behavior of air licking is also known as “fly biting” or “fly snapping.” Other dog owners describe it as a dog who is chasing imaginary things, up to the point of making them wonder whether their dogs are responding to some sort of
We often imagine seizures as the abrupt onset of uncontrollable muscle activity with the dog falling to his side, paddling and foaming at the mouth. These dramatic and scary episodes are known as gran mal seizures, but partial seizures are a type of seizures that are more on the discreet side.
Floaters are not limited to humans, they can affect dogs as well. What exactly are floaters and how do they affect dogs? Just like us, the dog’s eye is filled with a gel-like substance known as “vitreous.”
In some cases, licking the air has been found to be indicative of a digestive disorder. A
In behavioral medicine, licking the air and fly biting have been reported to possibly be caused by a compulsive behavior disorder. It’s a mistake to assume fly biting is behavioral issue from the get-go without first having the dog evaluated for underlying medical problems. Once medical problems have been ruled out, then, the next step may be consulting with a veterinarian specializing in behavior problems.
You might have heard about your friend who has been cheating on her husband or your co-worker may have told you how her boss hurt her feelings, but before making a judgement, have you heard both sides of the story?
Owners often describe the dynamics about a dog growling when asked to move off the bed as such: So I was walking through door and found Rover on my bed. I am not really too keen about having him sleep on the bed. So I first asked him nicely to get off. When I said “off” the first time, Rover ignored me. So I said “off” in a more serious tone of voice, leaning over him and pointing near his face. At this point, he even turned his head the other way and then yawned!
Let’s take a closer look at what Rover may be silently telling the owner before the infamous growl. Here’s his version. So I was sleeping comfortably on the couch. I like to stay on the couch because it feels comfy and my owner has allowed it in the past. Now here comes my owner telling me “off.” I tilt my head wondering what that means. It almost seems like she’s trying to say “woof?” Next, the owner says “off” in a more serious tone and looms over me in an intimidating manner. That was quite scary!
First of all, Rover often has no idea of what “off” exactly means. When dog owners are inquired about it, turns out their dogs were never really trained to respond to the “off” cue. We often assume dogs will naturally understand certain words when told in a firm manner, such as telling the dog “off” or
While the owner perceives the growl as the dog wanting to remain on the couch and “not giving up his throne” Rover is often not growling because of an intent to stay on the couch, but as a way to stop the owner from acting intimidating. Indeed, as soon as the owner leaves, the dog feels relief. In this case, for those interesting in learning how dogs learn, 
Of course, dogs may behave in certain ways for various different reasons, and there’s never a cookie-cutter explanation for all. If it were that easy, there would be manuals with step-by-step guides on how to fix dog behaviors just as those handy-man manuals tackling how to fix a leaky faucet making it feasible for everybody to do it.