'Dog Dust' May Combat Allergies and Asthma
Exposure to "dog dust," or the dried flakes of skin that fall from Fido, may protect against developing allergies.
University of Manchester
A pointer named “Major” is identified as the first known example of a modern dog. A description of the dog was found in a now-obscure 1865 edition of a Victorian journal called The Field. It marks the earliest reported dog breed based on physical form and pedigree. “The invention of ‘breed,’ physically and imaginatively, still shapes how we see and think about dogs today,” Michael Worboys, Director of the University of Manchester’s Centre for the History of Science, Technology and Medicine, told Discovery News. Worboys and his team found the information concerning “Major” while preparing a new museum exhibit on dogs.
The first domestication of dogs was thought to have taken place 31,680 years ago -- but new research suggests the skull in question likely belong to a wolf. This particular specimen was found with a still-visible mammoth bone in its mouth.
The paleolithic dog remains resembled a modern Siberian husky, but suggest an animals that was significantly larger. Today, the Siberian husky, Samoyed and Alaskan malamute breeds are all closely related. "The most remarkable difference between these dogs and recent dog breeds is the size of the teeth,” paleontologist Mietje Germonpré said. Other early dog breeds, with a focus on the U.K., are featured in the museum exhibit curated by Worboys and his team. Entitled “Breed: The British and Their Dogs,” the exhibit runs at the University of Manchester museum through April 14.
Another team of researchers, led by Heidi Parker of the National Human Genome Research Institute, used DNA analysis to determine the genetic relationships of numerous dog breeds. One such ancient breed is the Afghan hound. As its name suggests, it's native to the Middle East. It’s one of the oldest dog breeds in existence, and was originally used for hunting hares and gazelles.
Parker and her team found that Akitas are yet another ancient breed. These dogs originated in Asia and are genetically similar to chow chows. The breed was not included in the first dog show. “The first dog show was in 1859 when only two varieties were shown: pointers and setters,” Worboys said. It had nothing to do with the handsome Akita’s looks, as he explained that the first dog show was “for gun dogs only.”
The sleek-bodied saluki comes from Iran, where its distant ancestors might have once lived near the earliest farmers from the Fertile Crescent. Dogs in this region evolved the ability to eat a starch-rich diet around 12,000 years ago. “Our findings show that it was crucial to early dogs to be able to thrive on a diet rich in starch,” Uppsala University’s Erik Axelsson, who led a related study, told Discovery News. “That indicates that dog domestication may be linked to the development of agriculture. It is possible that dogs may have been domesticated independently at locations where agriculture developed early, such as the Fertile Crescent and China.”
One of the most ancient dog breeds native to the United States is the Alaskan malamute. The DNA study found that they are genetically similar to Siberian huskies. This large, muscular dog was used -- and still is -- for pulling sleds, hauling freight by other means, and for additional work tasks.
The basenji is “an ancient African breed,” according to Parker and her colleagues. While “Major” the pointer is the first documented modern breed of dog, the basenji is arguably the first dog to be heavily bred by humans. Although this dog hails from central Africa, paleontologists believe its wolf ancestors originally came from eastern Asia.
Remigiusz Józefowicz/Wikimedia Commons
In China, the chow chow is affectionately referred to as Songshi Quan, meaning “puffy-lion dog.” It is genetically close to the Akita, also from Asia. It represents yet another early breed.
Of the four most ancient known Asian dog breeds, the shar-pei was the first to diverge from a wolf ancestor, suggesting it is the oldest known Asian breed. This dog is famous for its deep wrinkles and blue-black tongue. Mutations of the same gene that causes wrinkles in these dogs can also cause wrinkling of human skin.
Exposure to "dog dust," or the dried flakes of skin that fall from Fido, may protect against developing allergies and asthma in later life by altering intestinal bacteria, a new study in mice suggests.
The dust appears to contain bacteria that, when present in an animal's gut, affects the production of immune cells in the animal's airway.
"Perhaps early life dog exposure introduces microbes into the home that somehow influence the gut microbiome, and change the immune response in the airways," said study researcher Susan Lynch, an associate professor of medicine at the University of California, San Francisco.
Past research has shown that exposure to pets, particularly dogs, during infancy may prevent people from developing allergies, and other work has found that bacteria in the gut can affect allergies and asthma. The new study adds to the research because it links these ideas — showing that the reason exposure to dog dust may prevent allergies is that the dust affects the population of gut microbes.
In the study, Lynch and her colleagues exposed mice to dust from a dog owner's home, and then tested the mice's immune response to cockroach allergens and ovalbumin (a component of egg whites), two substances that commonly trigger asthma attacks. They found that mice exposed to dog dust had fewer immune cells in the airway that respond to allergens, compared with mice not exposed to dog dust. [9 Weirdest Allergies]
The findings, detailed online today (Dec. 16) in the journal Proceedings of the National Academy of Sciences, hint at a mechanism for how dog exposure may protect against allergies or asthma.
"It seems to be that early life exposure to dogs, and cats to a lesser extent, can protect against asthma allergens," Lynch told LiveScience, though she stopped short of recommending exposing infants to dogs.
Lynch added that the findings fit in well with the hygiene hypothesis, the theory that a lack of exposure to beneficial microbes is linked to the development of autoimmune diseases and asthma in western nations.
The researchers also found the gut microbial makeup of the two rodent groups differed: The mice exposed to dogs had more of the bacteria Lactobacillus johnsonii, an organism found in the dust from dog-owner homes.
When the researchers added L. johnsonii to the diet of the unexposed mice, they found the mice showed a reduced immune response in their airways to both, though not as much as mice originally exposed to the dog dust.
The next step will be understanding exactly what these microbes are doing in the gut, and how they affect the immune response in the airway, Lynch said.
Ultimately, understanding this process could lead to the development of microbial-based therapies to treat or prevent asthma.
Original article on LiveScience
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