Tag: dogs

What Dog And Cat Years Really Mean?

How much is that in dog years?” We are used to assuming that for every calendar year, a dog will age the way a human will in seven years.

That makes some sort of sense according to a dog’s expected life span, but it doesn’t tell the whole story.




For example, the dog in this picture has one candle on her birthday cake, but she’s old enough to have puppies. Veterinary professor Jesse Grady explains the life stages of dogs and cats.

Dogs and cats age differently not just from people but also from each other, based partly on breed characteristics and size.

Bigger animals tend to have shorter life spans than smaller ones do. While cats vary little in size, the size and life expectancy of dogs can vary greatly – think a Chihuahua versus a Great Dane.

Human life expectancy has changed over the years. And vets are now able to provide far superior medical care to pets than we could even a decade ago.

So now we use a better methodology to define just how old rule of thumb that counted every calendar year as seven “animal years.”

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Pass it on: Popular Science

Can People Catch Cancer? Not Likely, But Some Animals Can

These guys are seriously threatened by a contagious cancer, largely because of how much they love to touch each other’s faces.

Recent headlines about contagious cancers found in some animals may make you wonder: Could I catch cancer? In Australia, Tasmanian devils are dying from aggressive facial tumors caused by a contagious virus.

In the Atlantic Ocean, some clams are developing a form of leukemia caused by cancer cells suspended in the water. And scientists have known for years that dogs can spread cancer cells from one to another during intercourse.

Despite recent headlines about cancer being contagious in other species, current data shows it’s virtually impossible in humans,” says Dr. Glen Weiss, Director of Clinical Research and Phase I & II Clinical Trials at our hospital near Phoenix.

“There have been attempts to transfect people without cancer with cancer cells, and it did not work.”

In the 1950s and 1960s, Dr. Chester Southam, a New York immunologist, conducted several controversial experiments by injecting live cancer cells into uninformed cancer patients and healthy prisoners.




While patients in both studies grew tumors, those in the healthy patients were quickly attacked and eliminated by their immune systems.

Foreign cells would more likely be rejected just like an organ donation or bone marrow transplant from a donor,” Dr. Weiss says.

In order to take, a recipient would likely require significant immunosuppression.” Southam was widely criticized for his experiments on humans and his medical license was suspended for one year.

Organ recipients are at a higher risk of developing cancer, but only in rare cases has the cancer been linked to the organ donor having cancer.

Such cases are so rare that some cancer patients are still eligible to donate organs. Some recipients develop cancer because the body’s immune system is suppressed to help prevent organ rejection.

Fortunately, survival of transplanted cancers in healthy humans is exceedingly rare and documented by only a small handful of cases,” Dr. James S. Welsh, a radiation oncologist currently with the Loyola University Health System writes in a 2011 article on contagious cancer.

“Thus, friends and family members of cancer patients and we, as caregivers of cancer patients, need not be unduly concerned with the remote possibility of ‘catching cancer.”

Humans may spread contagious viruses that lead to cancer. For instance, the human papillomavirus (HPV)  is responsible for virtually all cases of cervical cancer.

It is also linked to most cases of vaginal and vulvar cancer and more than half the cases of penile cancer. The virus is also linked to 90 percent of anal cancers and 72 percent of oropharyngeal cancer.

The hepatitis B and C viruses may lead to hepatocellular carcinoma, the most common type of liver cancer.

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Pass it on: Popular Science

European Colonization Of Americas Wiped Out Native Dogs Alongside Indigenous People

European colonisers arriving in the Americas almost totally wiped out the dogs that had been kept by indigenous people across the region for thousands of years.

The original American dogs were brought across the land bridge that once connected North America and Siberia over 10,000 years ago, by their human owners.

These dogs subsequently spread throughout North and South America, but genetic analysis has revealed they were ultimately replaced by dogs imported from Europe.

This study demonstrates that the history of humans is mirrored in our domestic animals,” said Professor Greger Larson, director of the palaeogenomics and bio-archaeology research network at the University of Oxford and senior author of the research.

People in Europe and the Americas were genetically distinct, and so were their dogs. And just as indigenous people in the Americas were displaced by European colonists, the same is true of their dogs.




In their paper, published in the journal Science, the researchers compared genetic information from dozens of ancient North American and Siberian dogs spanning a period of 9,000 years.

Their analysis showed the dogs persisted for a long time but ultimately vanished, which to Dr Laurent Frantz from Queen Mary University of London said suggests “something catastrophic must have happened”.

It is fascinating that a population of dogs that inhabited many parts of the Americas for thousands of years, and that was an integral part of so many Native American cultures, could have disappeared so rapidly,” said Dr Frantz, who was also a senior author of the study.

Today, few modern dogs possess any genetic traces of the ancient breeds.

The researchers suggested the dogs’ near-total disappearance from the region was likely a result of both disease and cultural changes brought over by Europeans.

It is possible, for example, that European colonists discouraged the sale and breeding of the dogs kept by indigenous Americans.

It is known how indigenous peoples of the Americas suffered from the genocidal practices of European colonists after contact,” said Kelsey Witt, who led part of the genome work as a graduate student at the University of Illinois.

Bizarrely, one of the only traces of genetic information from “pre-contact” dogs can be found in a transmissible tumour that spreads between dogs known as CTVT.

It’s quite incredible to think that possibly the only survivor of a lost dog lineage is a tumour that can spread between dogs as an infection,” added Maire Ní Leathlobhair, co-first author, from the University of Cambridge.

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Pass it on: Popular Science

Electronic Nose Could Aid In Rescue Missions

Anatomy of a super-smeller.

The olfactory system is based on artificial intelligence algorithms that enable the detection of the scent of alcohol, but with some modifications to the system and the algorithms it can recognize odors and toxic gases or elements.

“In rescue missions it might recognize blood, sweat or human urine,” said the former student of Tec de Monterrey.

In the first phase of development, the student wondered about how living things carry out the process of odor recognition and then transferred that knowledge to the mathematical sciences, and thus translated it into algorithms.

We note that, biologically, animals perceive the direction of an odor using two characteristics: it comes at different concentrations to the nostrils, and, because it is appreciated with a time difference.”

These two factors can identify from which a certain aroma comes,” explained the researcher.




This is how chemical sensors that mimic the nostrils, and which are separated by a septum, will perceive specific odors.

The data, said Lorena Villarreal, is sent by radio to a computer, where it is analyzed in real time to know the origin and direction of the aroma, using programmed algorithms.

Unlike other olfactory systems, this has the feature that in each cycle of ventilation the air chamber empties, making sensors ready for a new measurement,” says the doctor.

Thus, the technology takes only one cycle to detect that there has been a change of direction in the path of smell, which enables the robot to perform the tracking faster.

A noble beast.

Later the young researcher implemented this olfactory system to a robotic platform funded by CONACYT, to achieve its deployment to hypothetical emergency zones.

Blanca Lorena Villarreal is developing algorithms that allow the discrimination of odors, to give the robot some artificial intelligence that contributes to decision making processes.

For developing the “electronic nose,” the researcher has been recognized as one of the most innovative young Mexicans in the Mexican edition of MIT Technology Review, by the Massachusetts Institute of Technology.

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Pass it on: Popular Science

9,000 Year Old Rock Art From Saudi Arabia Is Earliest Depiction Of Domesticated Dogs

Carved into a sandstone cliff on the edge of a bygone river in the Arabian Desert, a hunter draws his bow for the kill.

He is accompanied by 13 dogs, each with its own coat markings; two animals have lines running from their necks to the man’s waist.

The engravings likely date back more than 8000 years, making them the earliest depictions of dogs, a new study reveals.

And those lines are probably leashes, suggesting that humans mastered the art of training and controlling dogs thousands of years earlier than previously thought.

It’s truly astounding stuff,” says Melinda Zeder, an archaeozoologist at the Smithsonian Institution National Museum of Natural History in Washington, D.C.

It’s the only real demonstration we have of humans using early dogs to hunt.” But she cautions that more work will be needed to confirm both the age and meaning of the depictions.




The hunting scene comes from Shuwaymis, a hilly region of northwestern Saudi Arabia where seasonal rains once formed rivers and supported pockets of dense vegetation.

For the past 3 years, Maria Guagnin, an archaeologist at the Max Planck Institute for the Science of Human History in Jena, Germany—in partnership with the Saudi Commission for Tourism & National Heritage—has helped catalog more than 1400 rock art panels containing nearly 7000 animals and humans at Shuwaymis and Jubbah, a more open vista about 200 kilometers north that was once dotted with lakes.

Starting about 10,000 years ago, hunter-gatherers entered—or perhaps returned to—the region. What appear to be the oldest images are thought to date to this time and depict curvy women.

Then about 7000 to 8000 years ago, people here became herders, based on livestock bones found at Jubbah; that’s likely when pictures of cattle, sheep, and goats began to dominate the images.

In between—carved on top of the women and under the livestock—are the early hunting dogs: 156 at Shuwaymis and 193 at Jubbah.

All are medium-sized, with pricked up ears, short snouts, and curled tails—hallmarks of domestic canines.

In some scenes, the dogs face off against wild donkeys. In others, they bite the necks and bellies of ibexes and gazelles. And in many, they are tethered to a human armed with a bow and arrow.

The researchers couldn’t directly date the images, but based on the sequence of carving, the weathering of the rock, and the timing of the switch to pastoralism, “The dog art is at least 8000 to 9000 years old,” Guagnin says.

That may edge out depictions of dogs previously labeled the oldest, paintings on Iranian pottery dated to at most 8000 years ago.

The dogs look a lot like today’s Canaan dog, says Perri, a largely feral breed that roams the deserts of the Middle East.

That could indicate that these ancient people bred dogs that had already adapted to hunting in the desert, the team reports this week in the Journal of Anthropological Archaeology.

Or people may even have independently domesticated these dogs from the Arabian wolf long after dogs were domesticated elsewhere, which likely happened sometime between 15,000 and 30,000 years ago.

Such a relationship would have been critical to helping people survive a harsh environment. Dogs could take down gazelles and ibexes too fast for humans, Perri says.

Details of the images also suggest that the ancient hunters tailored their strategies to the landscape, Zeder says. At Shuwaymis, where the dogs may have been used to drive prey into the corners of uneven terrain, the art depicts large packs.

At Jubbah, the images show smaller groups of dogs that may have ambushed prey at watering holes.

People were able to venture into these inhospitable areas by strategically marshalling dogs to survive,” Zeder says. “And now we’re seeing a real picture of how it happened.

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Pass it on: New Scientist

How Do Dogs Smell Fear?

The portion of the canine’s brain that is used for sorting out smells is up to 40 times the size of that same part of the human brain.

As for fear, being frightened can make humans sweat, an odor that a dog can easily identify.

Then there is adrenaline and associated hormones, which will pump through our bodies when we are are even a little nervous.

Just because we don’t know the “adrenaline scent” ourselves doesn’t mean that a dog won’t recognize it.

However, let me nitpick and say that being able to smell our sweat glands doesn’t mean a dog can literally smell the emotion of fear itself.




Most likely, playing a far bigger role in determining our level of fear is the canine’s outstanding ability to read our body language.

The dog feels our fear and senses we are scared just by watching us.

Dogs are very smart at figuring out our emotions. Anger, feeling threatened or being nervous cannot be hidden from a dog.

In fact, he may pinpoint your fears before you even realize them. People who are afraid of a dog often stare directly at it, probably in hopes of watching his every move.

But the dog may take the stare as a warning that he is going to be confronted, therefore becoming aggressive.

How do dogs smell fear? And can dogs even smell fear at all, in the strictest sense of the phrase?

The answer to these questions may never be known with certainty. But even though you’re an adult now, still choose to follow your parents’ teachings and not show your anxiety when approaching an unknown dog.

Whether your uneasiness can be smelled or sensed, always try to keep my cool.

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Pass it on: New Scientist