I wanted to add my 2 cents...
I have three female geese..I had four, but number four as it turns out is a true Gander.. I have also observed my female geese mounting. My chinese goose was very active in this behavior, and even plucked my sebastapol down to--well her down.. And she even mounted my other goose and the Gander. At first I thought that she was a he--and was really convinced.. BUT I also noticed that after these encounters my goose would go into her house and prep a place to lay an egg.
While this is not conclusive evidence to support or shut down ALL the arguments that have been made..and certainly doesn't explain every individual goose's motivation behind their behaiviors... From what I have observed in my own geese I have been able to draw one conclusion to explain their behavior: The egg or formation of an egg in the oviduct stimulated a breeding response from the goose.
I support this claim in light of the evidence that my ducks have also shown similar behavior.. I have a trio of mallards. One hen lays more eggs than the other, and this "egg laying machine" of a hen does excersise her dominance over the other hen when she is near to egg laying. She chases the younger more submisssive hen away from the drake, biting, pulling feathers, mounting, what ever it takes. Then she returns to the drake as the happy victor, and bobs her head up and down while making little quack noises and lowering herself to the ground--enticing him to mate. This hen will repeat this process until after she has lain an egg-- once that is done she and the other hen are best friends... the other hen will also bob and 'seduce' the drake, but she doesn't dare try to chase off the other hen...after seduction is complete..the hens like to go pick out a spot next to their house to lay an egg.. When the hens are not laying eggs, their battle for the drake is over, and peace is restored.
I also had three bachelor drakes for a while.. their behavior showed the differnt aspects of dominance....while they were together there was a strict pecking order. The pekin drake was at the top, the sweedish blue was second in command and accepted the pekin as number one from the start. My runner duck drake was at first aggressive, trying to bite the other ducks and chase them, then the pekin and the blue made him realize he was lower than the dirt he walked on. They would regularly mount him, chase him, and keep him confined to the interior of the coop. As a result of this jail house justice, the Runner (even though he is now seperate from the other drakes) has developed a submissive complex, and even submits to the hens--who are very confused by him, and I have one hen who takes advantage of his apparent "demoralization" by mounting him..
Like in humans 'Rape' (or sex from a scientific stand point), is a tool for Domination amongst waterfowl such as ducks. Dogs display mounting behavior too, but dominance mounting amongst dogs does not include penitration when males are involved--ducks don't seem to hold reservations about getting their 'jollies on' with another male--if it has feathers anything goes..
Domination doesn't need to be 'aggressive' or violent to establish dominance... humans establish dominance all the time without bashing someones head in, or raping them into submission.. Dominance can be earned through respect, or mutual understanding. you accept your Boss at work as being your boss, and you have to respect his/her decision--you are submitting to the Dominance of your Boss.
You are taking your dog for a walk, and he sees a squirl he wants to chase and pulls hard on the leash, you tell him NO, he looks at you, aknowledging that he respects your wise decision, submits to your Dominance and stops pulling on the leash..
I think the observation, or assumption that Dominance is mostly violent/aggressive is false, and unfounded. There are violent and aggresssive forms/ways to achieve dominance, but to define it as "violent" and using that to defend a point is ignorant.
Back to the dog.. there are many documented cases where dogs have expressed an over exagerated need to mount objects/people in their effort to gain control over situations in their lives which is often refered to as "dominance." Dominance, like "aggression" is a very loose term when speaking in refernce to dogs. Many people do not understand their dogs behavior because they do not know how to read a dog, nor do they know the root of what may be causing the apparent changes in behavior-- so they simply refer to these terms in an effort to describe one of the symptoms that is being presented.
I agree with you that your vet is wrong. Veterinarians are doctors and surgeons, they are NOT behaviorists. They don't study animal behavior, nor do they specifically treat the mental afflictions that dogs develop as a result of their living environment. But I would also caution you on assuming that your dogs motivation is strictly for pleasure--- the "expressions" on a dogs face were bred into them over thousands of years to mimic our own expressions--their ability to do this made them worthy pets. What you see as being "pleasure" is most likely "relief" your dog is relieving itself of some sort stress by acting out in what some people might falsly call a "dominant" behavior.
I have never met your dog, or observed it, and therefor I cannot say for certain what is causing this behavior, BUT it sounds to me more like your dog lacks pack structure--its sounds terrible and judgmental I am sure when you hear that, but the average dog does not recieve the type of structure or understanding that they need.
They are pets and are treated like they are human children, your dog no doubt loves you, but certain things that humans do (or DON'T do enough of CORRECTLY..) for their dogs does actually cause them alot of stress that their humans never realized/thought would ever affect their dog the way it did...this stress is manifested as Anxiety; anxiety in dogs can be expressed in different ways depending on the individual being affected. If you ever interested in understanding the real reason your dog behaves the way it does, and are dedicated to fixing it, I would talk to a licensed behaviorist in your state instead of a vet.
