My friend Paula has a Wire Fox Terrier, Mr. Charles.

Not known for shyness, this breed — like all terriers — was used as a farm dog. Some terriers were used to hunt rodents, while others guarded the farm. The word terrier comes from the word "terra" or "earth."

A few years ago, Paula started “playing” with Mr. Charles using an LED light. Some friends that have cats tell me they use these toys, which are marketed for felines as a source of stimulating play.

Mr.Charles is now obsessed with the light — as well as shadows — even a light coming from a mirror. The behavior has progressed to Paula’s car. In the car, he will stand still, obsessed with following lights from her rear view mirror. Paula tells me he will stand fixated in a corner, seemingly looking at nothing.

“I wish”, she continues, "that I had never started using that light.”

When dogs are fixated on a particular object that creates destructive behavior, this is considered an obsession.

Obsession can begin with something as simple as an injury; hot spots crated by allergies, insect bites — and, yes, even boredom.

Monica tells me that her beagle continuously licks her wood floors. Monica is worried Susie will get splinters in her tongue.

When obsessive licking goes unnoticed Acral or lick granuloma forms. Acral licking — also known as lick granuloma — - occurs when the dog licks itself continuously to the point that a permanent open lesion remains on the skin.

One of the Jack Russell terriers that I worked with exhibited acral licking. While the dog lived on a farm and was running around all day, the activity did not stop the licking.

These behaviors begin innocently: in some cases, the dog has a skin allergy. Licking starts, and within a few days a sore has developed where the licking is concentrated. At this point, a trip to the vet is essential. If stopped, the new problem can be reversed.

My friend Deb’s dogs are workers. Having Border Collies, Deb competes them in agility trials — rally obedience, more specifically. Deb takes them swimming too. These are not dogs who laze around. She even has her terriers on the treadmill every morning for over 20 minutes!

So when one of Deb’s dogs began licking and chewing, Deb tried everything. It didn’t help that Deb was at an agility trial far from home when all of this began.

What Deb used to try to stop her dog did not work. The dog chewed through every bandage she put on her to get to that spot. The dog lapped up the bitter apple spray that was used. Deb spent a sleepless night trying to keep her dog from chewing the spot.

As a person who prefers natural remedies, she had to resort to a very strong course of prednisone to internally stop whatever caused the licking.

As you can see, obsession is a complex issue. It is important to know your dog.

So, what does that have to do with obsession?

Let's examine a few things:

Does your dog chase its shadow when it goes outside?

Chasing light, its tail, spinning in circles — any of the behavior for longer than one minute?

Does your dog frantically run from the couch to the window seemingly without end? When you call the dog, does he/she ignore you, continuing the behavior?

Do you plop down on the sofa shortly after you get home from work, and then yell at the dog to stop its rather frantic behavior?

It doesn’t matter if your dog lives on a farm — dogs need the challenge of a job. A job can take many forms:

Playing catch, throwing a frisbee, going on a long walk.

Dogs adapt very easily into our lives, but when they're confined to a house all day, even the biggest, most beautiful home is just a kennel to a dog.

When considering breed, certain characteristics define what makes a Sporting breed different from a Toy breed. With any breed, from the largest to the smallest, leaving a dog alone all day and not assisting in some form of exercise is in the evening creates a problem for you and your dog!

And, know yourself: are you a sporty, active person or do you like to stroll around the Arb?

Whatever breed your dog is, please determine if the obsession is physiological first!

Check to make sure your dog does not have allergies. When purchasing a purebred dog that has a tendency toward skin allergies, ask the breeder if the dam and sire have allergies.

Allergy testing is very common now for dogs, and sometimes the allergies are food related. My friend Marilyn’s Wheaten Terrier is allergic to chicken products. Now that is a challenge, as even some medicines come in chicken flavor to make them palatable.

My greyhound was allergic to wool. Up came all of our throw rugs.

If you have gone through your checklist, allergy-tested your dog and given it a job and the obsession continues, backtrack. Make a list when the obsession began. Like most behaviors that begin innocently; we only notice when they become very obvious.

Please don’t be mad at your dog. Your dog is not doing this to annoy you. It would be extremely difficult if you couldn’t tell your doctor, "Ouch! This is where it hurts!"

With obsession, we need to put on our deerstalker hat and play detective.

Julia Levitt is the founder of In Harmony Dog Training (www.inharmonydogtraining.com) in Ann Arbor. She can be reached at julia@inharmonydogtraining.com or at 734-645-4707. Julia also teaches dogs and their owners at Ann Arbor Animal Hospital.