Think about normal and problem companion animal behavior. Of all the biological variables that contribute to it, which attribute has the greatest influence?

Some would say the animal's species- and breed-specific genetic makeup has the greatest impact. Others might place more emphasis on maternal care or nutrition. Relatively few, however, will mention the quality of the biological and behavioral effects of the human-animal bonds (HAB) that form between an animal and the people with whom the animal lives and interacts.

Multiple factors contribute to this oversight, a major one being different definitions of the HAB that reflect different contemporary human perceptions of it.

Some people define the HAB as the mechanism by which animal companionship triggers beneficial changes in human physical or mental health, and the equally beneficial changes in behavior and physiology that accompany these. This common definition currently drives the burgeoning market for service and (real or fake) emotional support animals.

For other people, the HAB elicits images of pet loss and the negative behavioral and physiological effects people experience when such a loss occurs. Still others define the bond as the backbone of a solid marketing and public relations strategy.

Finally, the HAB represents a concept animal care professionals may pull out when all treatment options have been exhausted or refused and the animal's problems persist. As in, "I did my best, but the bond just wasn't there."

Despite their differences, those who ascribe to one or more of those definitions share one thing in common: They all perceive the HAB primarily as a unilateral, anthropocentric concept. They measure the bond's strength and quality in terms of how the animal's presence benefits them or other people.

As popular as the more anthropocentric definitions are, scientific studies of the effects human presence has on animal behavior and physiology predate those that explored the converse.

Ivan Pavlov noted the beneficial effects a calming human presence had on canine heart rate. One of his students, W. Horsely Gannt, and others conducted further studies that collectively became known as "Effect of Person."

More recent research in dogs and horses further confirmed something many suspected: The animal's physiological and behavioral response to a person could be influenced by the body language and physiological cues the animals receive from that individual.

Those who feared or disliked the animal for some reason would elicit a different physiological response from the animal than those who didn't communicate those negative emotions. People skilled in reading animal body language could detect differences in this form of expression, too.

As the bond between humans and companion animals became more unilateral, people simultaneously became more fearful of their animals. This frequently can be traced to the lack of basic ethological knowledge that accompanied the transition from an agrarian to a suburban and urban society.

Without this knowledge of animals as separate beings with their own species- and individual-specific needs — some similar but others different from our own — it's much easier to perceive animals symbolically. Common symbolism includes that of companion animals as "fur babies," "fur kids," show champions, star athletes or 24/7/365 physical and emotional protectors. In some situations, people may develop a stronger bond with what their animals symbolize to them than with the animals themselves.

If the animal possesses the physical and mental soundness to fulfill any obligations the owners' symbolism imposes without any negative effects, the human-animal relationship and resultant bond will work. On the other hand, if the nature of the bond is such that the person needs the animal to fulfill a role the animal cannot, then two things may happen.

The person may give up or euthanize the animal, or the stressed animal may develop behavioral problems, including fear-based aggression. And when aggression occurs, these people may need to face any fears regarding the animal's potential to harm them or someone else before they can resolve the problem.

In general, fearful people fall into one of two groups: those who acknowledge their fears and those who don't. By far, those who acknowledge their fears have the advantage when it comes to helping their animals.

These people embrace the idea of wearing whatever protective clothing it takes to enable them to interact confidently with their aggressive dogs; many even apologize for not thinking to do this themselves. These people also are willing to change their own behaviors to help their animals instead of expecting their animals to do all the changing.

Those in this group additionally display two other qualities — a sense of humor and the ability not to take their animal's negative behavior personally — that enhance their and their animals' success.

Increasingly, the fear-deniers seem to outnumber the fear-accepters. But although they may be able to deny their fear to themselves or other people, they may not be able to fool their fearful dogs in protective mode.

Admittedly, the idea of being afraid of one's own dog may seem laughable to practitioners used to working with all kinds of dogs under all kinds of conditions. However, for those outside the profession, it may be possible to achieve this state with relative ease.

A growing array of flavored, long-acting or injectable medications relieves pet-owners of the need to restrain their animals, let alone handle their mouths. Groomers relieve people of the more restrictive physical contact associated with bathing, brushing or nail-trimming that owner-protective fearful animals often resist from the people with whom the animal lives.

Instead of teaching people how to take away forbidden objects the dog has stolen, some trainers teach owners to trade these objects for treats. When people accept these sanctioned hands-off approaches to their dogs as the norm, it's much easier to deny that any fear of their animals exists.

Magicians and gamblers often speak of "tells," unconscious actions by others that signal an attempt to deceive. My first experience with client fear-related tells occurred as a young veterinarian in veterinary medical practice.

During an eight-week period, I did weekly exams on a 2-year-old, neutered, male, German shorthaired pointer with an intramedullary pin in his femur. I'd pick the dog up, place him on the exam table and give him a complete physical. Then, I'd zero in on the injured leg, checking for signs of existing or potential problems.

While I examined the dog, the chatty client talked almost nonstop about what a wonderful dog he was. Like many problem-oriented practitioners, I'd periodically nod or give her a cheerful smile to indicate I was listening. But I really wasn't; I was focused on the dog's medical problem.

However, it turned out that even though my conscious mind wasn't paying attention, my subconscious was. I discovered this several months later when the dog seized the client's young son by the face when the child tried to pet the dog resting on the owner's bed.

In that instant, I realized the client had been telling me right along that such canine behavior was a real possibility. But back then I'd disregarded it because of my ignorance of companion animal ethology. Because the dog's behavior was good with me, I naively considered it a nonissue.

In retrospect, this tell is easy to spot. It takes the form of remarks that begin with the phrase, "(Insert animal's name) is a great dog unless ..."

Because my client and her husband were afraid of their dog, they carried all kinds of rules in their heads regarding what they and others could and couldn't do around him lest he growl or snap at them. Their list included not bothering the dog when he was on their bed, a rule their 4-year-old son either forgot or never knew.

Over the years, the list of things people won't do with or to their animals because they're afraid of the animal's response has grown: clipping nails, grooming, exposing the dog to kids/men/only men with beards/anyone with an umbrella/motorcycles/ UPS or Fed-X trucks, etc.

One of the saddest is owner fear of hugging or otherwise expressing affection for another person or animal in the fearful protective dog's presence. One of the most common is fear of taking something out of the animal's mouth, even if the animal is choking or has snatched something toxic.

Another fear-related tell takes the form of giving treats or having others give treats to dogs displaying fear-based aggression. When the behavior persists, most people asked to explain what's really going on give the right answer: They and others are rewarding the problem behavior which, in turn, causes the animal to repeat it.

While some owners end this negative cycle, others cannot. Their fear is so great, they want to placate the animal any way they can.

But while tells can be helpful, simply asking, "Are you afraid of this animal?" in a nonjudgmental way can lead to meaningful client communication about a subject that can negatively impact both human and animal lives.