Emotions impact behavior in animals the same as they do in people. We are animals, too, after all.
THE CORE EMOTIONS
The Seven Core Emotional Systems (outlined by neuroscientist Jaak Panksepp) are shared by humans and other animals.
SEEKING - anticipation, expectation, hunting, foraging, investigating
PLAY - joy, social interaction, enjoyment, recreation
CARE - nurture
LUST - sexual desire
FEAR - anxiety, fight or flight response
RAGE - anger, frustration
PANIC - sadness, loneliness, grief
SEEKING, PLAY, CARE, and LUST are positive emotions. Laboratory animals will choose to activate these when given a choice. FEAR, RAGE, and PANIC are negative emotions. Lab animals will work to avoid activating these.
We can influence emotions in our dogs. We can activate SEEKING by feeding them from toys instead of a bowl, playing hide and seek, scent work, tracking, and other search and exploration games. We can activate PLAY by providing toys our dog enjoys, playing tug, fetch, or "the claw" (make your hand into a claw and pretend to eat their face with it), and by setting up play dates with other dogs.
Our goal is to minimize negative emotions as much as possible. The old methods of dog training worked on the FEAR system (escape, avoidance, do this or else). Positive training methods use SEEKING and PLAY, resulting in more trusting and satisfying relationships with our dogs, less aggression and fearfulness, and improved welfare for dogs.
It's clear to anyone who lives with a dog that they experience the Core Emotions. What is less clear is whether or not they experience more cerebral emotions such as Guilt and Spite. The Core Emotions are primitive and do not involve the frontal lobes. You don't think about it, the emotion just happens. If you see a rattlesnake, you don't think about being afraid of it. Your reaction is involuntary.
Guilt and Spite, though, have some frontal lobe involvement. They require thinking. Guilt isn't an automatic response. It comes from thinking about how you may have hurt someone. It requires a sense of morality ("right" and "wrong") and the ability to think about another person's perspective and how you might feel in their shoes. Spite requires the ability to think about and plan to do something that another person would find hurtful, even if that something wouldn't be offensive to you. Animals have a far less developed frontal lobe system than humans. Do they experience emotions that require thinking about emotions? Do dogs possess emotional reasoning?
So far, studies point to NO. What we perceive as a guilty look from our dogs is the FEAR system. Repeated studies have shown that dogs appear guilty, even when they aren't, if the owner believes they are guilty. Dogs are expert body language readers and can pick up on subtle signs of disappointment, frustration, or anger, even when we don't say a word. The evidence shows that guilt and spite are too complex for dogs to experience. Even if a dog was capable of showing spite, there is definitely something wrong in your relationship if they are trying to spite you!
FLIGHT ZONES AND FIGHT ZONES
The FLIGHT zone is how close you can get to an animal before it runs away. Domestic animals have smaller flight zones than wild ones, but some wild animals don't run away until you get very close. Think of squirrels or ducks who are used to being fed by people. They'll get close, but they'll run if you try to touch them.
The FIGHT zone is how close you can get to an animal before it becomes defensive and bites. We've all been taught to never back an animal into a corner. If we take away the FLIGHT zone, and someone gets too close for the animal's comfort, FIGHT could be next (some animals FREEZE).
Leash reactivity and aggression often come from someone being too close to the dog's personal space. They can't FLEE, so FIGHT is their only defense. If the dog has learned that a leash removes their FLIGHT option, they will begin displaying lunging, snarling, and barking behavior from even greater distances, trying to keep the other dog or person from coming any closer because they don't have the option to move away themselves.
To prevent leash reactivity / aggression, don't allow another dog or person to violate your dog's personal space. Make it the default behavior that if you see another dog or person on leash, ignore them. If you must walk your dog too close to another dog or person because it's a tight space, physically place yourself between the other dog or person and your dog behind your hip in a protective stance. Move quickly to get past them and reclaim your dog's personal space. Think of how you might feel if you were handcuffed, and a large man was running at you as fast as he can. You would likely feel threatened, even if this stranger "just wanted to say hi". Do not allow your dog to rush up to another dog who is on a leash. It's rude, even for dogs.
This dog would run away if she could, but she's trapped by the leash. She will bite in self-defense if touched.
"High arousal makes us stupid." - Karolina Westlund, Ph.D.
When animals are in a state of high arousal or excitement, they aren't able to think. They can't learn new things, and they can't access things they have already learned. The lizard brain kicks in and they are reacting more than thinking. Maybe this (and alcohol) is why there are so many fights at sporting events!
Fine motor skills are impaired, also. An overly excited dog has less control over their body. This is why they may start to take treats too hard and shark your fingers.
High excitement can be good (you're seeing your favorite singer in concert for the first time, your dog is doing zoomies around and around the yard)... and it can be bad (you're late for an important meeting and can't find your car keys, your dog has been left alone for the first time and they panic and run frantically from door to door trying to escape).
It's an exercise in futility to try and train a dog in a state of hyperarousal. Remove the dog from the situation or change the situation, and gradually increase the challenge of the environment as your dog can handle it.
image by Karolina Westlund, Ph.D.
Every dog experiences pleasant and unpleasant moods and high arousal and low arousal states. If they spend too much time in unpleasant moods and extreme arousal states, their welfare will be low. Our job as their guardian is to keep them in the right, middle side of the diagram as much as possible.
...the straw that broke the camel's back
We've all experienced trigger stacking. It's when you're having a bad day, and one thing after another goes wrong until that one more thing finally pushes us over the edge and we explode! Dogs experience this, too. The vet stuck them with needles, they got car sick on the ride home, they don't get a nap because it's the kid's playtime when they get home, somebody accidentally stepped on their paw, they finally get comfortable on the couch and the other dog tries to play with them and they just SNAP! It was the final straw!
Be aware of things that cause stress and try not to pile them on all at once, if possible. GOOD stress (eustress) also counts. Maybe your dog had a great time at doggy daycare, but they want to rest when they get home and not have the neighbor's dog come over to play. It's like when you get home from a dinner party, had a wonderful time, but now you want to kick off your shoes and watch t.v. and not have surprise company over.
Empathy helps us better understand our dog's behavior. Put yourself in your dog's paws and think how you might feel in a human-equivalent situation. We must set aside our ego and realize that most of our dog's behaviors aren't about us. They're not trying to be the boss or get away with something or to spite us. They are trying to cope with their world with the information and tools that they have, the same as we are.