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The keen senses of the canine: your dog's 'view of the world' enables her to explore her environment much more thoroughly than we can.

Dog owner Patricia Marland of Rochester, New York, describes her terrier mix, Annie. "She's always mouthed my hand when she wanted to go out and scratched on the door to get back in. After a while, she began doing that when she'd see the cat waiting on the back porch to be let in or out."

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Being the smart dog that she is, Annie uses a combination of her sense of touch, sight, hearing and possibly her sense of smell to get her needs met--and even those of her feline housemate. According to Marland, "I didn't train her to do this--she just did it on her own."

To understand dogs and why they do what they do, you'll need to know how they use their senses to respond to their environment. Consider this: Dogs hear and smell things that humans completely miss, but did you know that they also have the ability to tell the difference in the fingerprints of identical twins?

According to Katherine Houpt, DVM, PhD, professor of physiology and animal behavior at Cornell University's College of Veterinary Medicine, it's not surprising, as dogs have a thousand times better sense of smell than do humans.

Sense of Smell. Many four-legged animals including dogs have a keen sense of smell and are macrosmatic, which means they have a greater level of olfactory function with a complex nose design, as well as a large olfactory lobe in the brain. The sense of smell is a dog's most highly-developed sense. Smells are a form of communication, a way to mark territory and a method of tracking friends and enemies.

"Dogs use the sense of smell in conjunction with taste to determine desirable and undesirable food," says Larry Myers, associate professor of anatomy, physiology and pharmacology at Auburn University in Alabama.

"The sense of smell also helps dogs find mates," he adds. Anyone who has owned a female dog in heat knows that they draw male dogs from miles around. "One of the chemicals the male smells is mphB or pheromones," Dr. Myers says. Additionally, a canine's more developed sense of smell is linked to situational or environmental stimuli.

"If the dog lives in the wild, smell is important, having to do with environment," says Mark Russak, DVM, assistant clinical professor at the College of Veterinary Medicine at Mississippi State University. "It depends on what the dog is used for. A bloodhound's sense of smell is key to search and rescue missions," Dr. Russak says.

We know that a dog's sense is highly refined, but we've all seen our favorite pooch stuff her nose into a box for a closer sniff. Could dogs be seeking out more detail than what is available on the outside? "Yes," says Dr. Houpt. "The most interesting example: Watch a dog with snow. They'll stick their noses in every footprint." She adds, "When owners arrive home, often dogs start sniffing them all over because they want to know where they've been. My indoor cat does this to the dog."

Often our canine companions have jobs to do, such as guiding the blind or hearing impaired, sniffing out bombs or drugs, search-and-rescue, or aiding in therapy.

Sense of Sight. Dogs depend on their eyesight to capture prey, to move around in their world and to recognize their owners, among other things. Dr. Houpt says, "Dogs learn best through observing their mothers and siblings, and through repetition and praise. But their visual acuity isn't very good. Human vision is 20/20, dogs are 20/80 and a horse is 20/200."

She notes a Cornell study that involved shooting video footage of small dogs in their homes. "The dogs were often looking up to see the owner's face to determine who they were and what their owner wanted."

Combining sight, smell and hearing, a dog will see you immediately and stare. Call his name and you have his interest--but when you get close enough for him to pick up the scent, then he recognizes you and becomes a happy dog.

"Dogs don't read newspapers or drive cars," says Dr. Russak. "Their sense of sight is completely different than humans. Their eyes are built differently for distance and motion viewing. Dogs have good distance vision and different receptors, seeing better in the dark." Dogs are masters of compensation, with no better example than a dog that's been sighted from birth and loses its sight.

Dr. Russak says, "A blind dog will change how it relates to the world. They can do incredibly well without sight as long as you don't change their environment. No open stairwells, no sharp objects, and they can walk the entire house. If you have a dog that is going blind, don't give up on it."

A perfect example is Puggy, a pug that went blind as she aged. She learned to balance that loss by depending on her sense of hearing to get around.

"We learned not to move furniture," says Belinda Thompson of Illinois. "She even went up and down stairs by use of voice commands."

"Dogs hear between 20 and 40,000 hertz and humans hear at 20 to 20,000 hertz," says Dr. Myers. "Dogs aren't necessarily more sensitive in hearing, but their auditory threshold is more sensitive and they can hear much more than we can." The reason for this, according to Dr. Houpt, is that dogs can hear at higher frequencies to track rats and mice. Puppies often make high-frequency sounds, but that ability lessens as they get older. "Hearing and the sense of balance are in the same organ, the ears," Dr. Houpt explains.

Dogs can feel pressure, pain and temperature via their skin and have a finely developed sense of touch via the hairs, whiskers and nerve endings that cover their bodies. About whiskers, Dr. Russak says, "Whiskers are a minor part of their anatomy now. Humans protect dogs, so they don't need their whiskers as much. If dog owners trim whiskers, it will impair their sense of touch around that area, but the whiskers will grow back."

we've all known dogs that don't like to be touched and others that can't get enough cuddling. Socialization in the first few weeks of life can be critical for sensitivity to touch. According to Dr. Houpt, "Some dogs, like terriers, are more aloof, but owners can massage their dog and get it accustomed to touch."

Sense of Taste. Unlike cats, dogs can taste sweetness. And they have preferences, just like humans. Some dogs like turkey and giblets and others like fish. In addition to the ability to taste sweet things, dogs also can taste sour and salty things. Dogs' taste buds tell them that sweet is a safe taste. Unfortunately, this can get them into trouble.

"An example is antifreeze, which tastes sweet," says Dr. Russak. "If you pour a pool of antifreeze on the garage floor and a pool of water, the dog will lap up the antifreeze because it is sweet, even though it will kill him."

Dog are known to eat things that aren't necessarily good for them. "They will eat feces but we don't know why they do it," says Dr. Houpt. "Low-residue diets tend to encourage this behavior by making their stool finer."

WARNING: KEEP YOUR DOG SAFE WHEN OUT ON WALKS

You're excited because it's a beautiful Saturday, and you want to take your dog for a long walk. You decide you'd like to dash into a department store or break for a bite to eat at your favorite restaurant. So far, so good. Then you make the fateful decision to tether your personable pooch to a lamppost while you take care of your errands, right? Wrong. This practice can not only be hazardous to your dog, but dangerous to passersby as well. Imagine the following scenarios. Your dog might:

* Bite someone. He could easily become startled or frightened and bite a pleasant person who stopped to pet him. This might lead to legal woes and a mountain of medical bills that you would be forced to pay. If that thought isn't enough to deter you, consider that your local animal control agency might quarantine your dog for several days after a bite incident. (A word of caution: dogs should always be up-to-date on their rabies shots and other vaccines.) Children are especially susceptible to dog bites, as they don't understand the inherent danger unless a parent has warned them against approaching a strange dog.

* Attack another dog. Another animal that approaches might also become the victim of an altercation with your dog. Even the friendliest dog can feel threatened when confined in an unfamiliar area. If your dog happens to be aggressive toward people or other pets, it is especially important not to leave him unsupervised.

* Be stolen. Unfortunately, pet theft is more common than you might think. According to StolenPets.com, more than two million companion animals are stolen in the United States every year.

* Become entangled in his leash. This can cut off circulation to his neck, legs or other body parts.

* Bark incessantly. Dogs tend to voice their displeasure when left alone or may bark just because they are excited to see a friendly face. However, barking can be annoying to restaurant diners who are trying to enjoy a meal on an outdoor patio.

* Relieve himself. Urinating or defecating in a public area, especially near restaurants, can pose a very real health concern. Keep in mind that most city and state health agencies strictly enforce their safety regulations and exclude all but service dogs from restaurants, even in patio or outdoor areas.

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Title Annotation:NOTEWORTHY
Publication:Dog Watch
Date:Oct 1, 2010
Words:1606
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