As I learned more about the interaction of animal behavior, health and the bond, my disenchantment with the canine "sit" command steadily grew. Eventually, I eliminated it completely from my patients' behavioral repertoire.

Then and now, it serves as another good reminder that there's no such thing as just a medical or behavioral or bond problem. Change one, and the other components will change.

Consider the canine rear end. In addition to the role it plays in locomotion, a stable rear end plays in a vital role in defensive or offensive canine display.

Most people who routinely work with dogs, especially fearful ones, learn to see — and sometimes just feel — the split-second postural shift the precedes an attack. FSL: freeze, shift, lunge. The standing dog freezes, shifts his weight to the rear end and lunges.

Like most practitioners, I began seeing more dogs carrying excess weight that hampered their mobility in my behavior practice. Additionally, descriptions of hip or knee problems increasingly appeared in these animals' histories as well as the histories of their less portly cohorts.

In most cases, pain medications and surgery enabled these animals to move more freely most the time. However, owners also noted their dogs' reluctance to obey the sit command. Those who did would soon drop into a down position.

This leads us to the question, why do dogs normally sit? Do they sit to relax as humans often do, or do they do it for some other reason?

If you observe dogs singularly and in groups, you discover sitting often represents a sentinel position. It's what dogs do when they're monitoring their environments for some reason. In the case of dogs with fear-based aggression or separation anxiety, perhaps they're on the alert for the sound of the delivery truck or school bus so they can defend their territories from the vehicle or its occupants.

Or maybe they await the appearance of other dogs who have the audacity to violate the space these canine sentinels so carefully previously marked on their morning walks. To that end, they sit upright in their screened porches, on the backs of couches or from other key lookout locations within the confines of their yards or homes, on guard and waiting.

On the other hand, I discovered many of my clients used the sit command at times when they wanted their dogs to relax. The conflict this created for the dog often resulted in a major breakdown in human-canine behavioral communication. A common example of such a conflict involves making a fearful dog sit under conditions the animal finds frightening — e.g., during the kids' soccer games or during a parade.

Regardless of the exact circumstances, people often comment that dogs who experience behavioral (as well as sometimes physical) pain when they obey the sit command exhibit two other telltale signs. Instead of sitting with their rear ends firmly planted on the floor or ground, some of these dogs will balance themselves on their front feet.

Other times, the dogs display what I think of as a "vibrating sit." They sit but their whole bodies tremble with the stress generated by assuming a position that causes them physical and/or behavioral pain for some reason.

This inextricably entwined behavior, bond and animal body connection creates a chicken-egg phenomenon.

The kinds of behavioral and bond issues that result in chronic, intermittent shifts in body position that evolved for use under survival conditions eventually can take a toll on the canine musculoskeletal system. But changes in the musculoskeletal system compromise a dog's ability to protect the territory and those in it if the nature of the bond dictates this may cause a dog to display more offensive or defensive behaviors faster and sooner.

But although we all love those quick-and-dirty lists that state "Behavior A means B and guaranteed Solution C," no such inviolate connections exist. For example, you might assume from the above that a dog in a down position would be more relaxed than that same dog sitting. However, this also may or may not be true.

My personal introduction to this reality occurred during a training seminar I attended early in my career. One of the demonstration dogs used by the speaker during the presentation was a shelter dog with horrendous rear end confirmation.

Despite this physical limitation, the dog appeared to move easily as he walked loose-leashed through the group and up the few steps to the stage with the trainer/speaker. Even so, something about the dog literally made the hairs stand up on the back of my neck as he walked by me. Back then I dismissed the feeling as foolish.

Once on the stage, the dog immediately laid down on command, but with both rear legs awkwardly extended to one side. For the next 10 minutes or so he calmly balanced on his front legs and observed his surroundings while the speaker continued her talk.

Who knows what seemingly insignificant stimulus took this animal beyond his threshold? Perhaps it was the scent and sounds of the meal being prepared in the room adjacent to the auditorium. Or maybe he caught one of the other dogs in the room staring at him. Or maybe the combination of the two.

Whatever it was, it caused him to lunge aggressively and without warning using only his front legs and anterior body strength to propel himself. Fortunately, the trainer had kept hold of the leash and eventually got the dog under control enough to remove him.

Increased experience combined with my veterinary training and a more detailed history of the dog later enabled me to realize what my primitive survival brain unsuccessfully attempted to communicate to me when he walked by me. He was too calm; he was too self-contained; he appeared too normal given his physical limitations.

Ultimately, I concluded that he had survived for as long as he had on the streets because he'd learned not to waste energy on any displays that might signal vulnerability in any way. No growling, raised hackles or dilated pupils.

When he became part of the shelter's culture, he adapted and did well. Take him out of it, though, and it became obvious that he continued to play by canine and not human rules.

Like animal health, animal behavior is dynamic. Environmental and bond conditions that pose no problems one day may create them the next. While a dog's limping may appear suddenly, radiographic and other diagnostic evidence may make it clear that the changes that triggered the limp evolved over a much longer period.

Similarly, behavioral problems that arise from or contribute to rear end instability may appear to occur out of the blue. But with a comprehensive behavioral and bond history and work-up, more often than not, the reason for the seemingly inexplicable becomes clear.