Furry Friends and Beneficial Bugs

This is my nephew Ethan with my dog nieces, Mika (left) and Chloe (right). 

They say that dogs are man's best friend. What's not to love about a dog? They offer companionship, protection, and let's be honest, we love having them there to clean up any food spills we make on the kitchen floor. In case anyone isn't convinced that dogs are super awesome, it has also been demonstrated that dogs can improve gut health and alleviate the symptoms of allergies. Too good to be true? Let's hear some of the facts.

Researchers found that dogs contribute to an increased diversity of bacteria in house dust and exposure to this house dust actually dampens the allergic response to several allergens. It's like magical pixie dust, except it probably can't make you fly. The way researchers tested this was by feeding different types of dust to mice. Makes you wonder where dust falls on the food pyramid. They fed one group of mice house dust from a house with dogs and to another group of mice they fed house dust from a home with no dogs. The mice that were fed the dog house dust showed a decrease in airway immune cells and other components that are important players in the allergy response. So basically, the dog house dust told the mice's immune system to chill out a bit, there was no reason to overreact. Development of childhood allergic diseases are known to be associated with overactive airway immune responses. This means that exposure to dogs during infancy might reduce the risk of developing diseases such as asthma and atopic dermatitis. Neat!

Like any good scientist, the researchers had lots of questions after they made their findings. In the world of science, one answer only leads to many more questions, the most important being, how does this work? So they examined the mice, specifically what was in their gut. I'm sure you all know that your gut is the home of a community of bacteria that are incredibly important for digestion, protection from bacteria that can make you sick, and just overall body health and function. It's like I always say, bacteria are my friends! They found that in mice that were fed dog house dust, there was an abundance of one specific species of bacteria called Lactobacillus johnosonii. This species can also be found in the human intestine and is part of a group of bacteria that are associated with probiotic activities.

This is an image of stained Lactobacillus acidophilus cells.
There are many Lactobacillus species and they live happily in our urinary,
 digestive, and genital systems. They are also found in fermented foods
like yogurt and in probiotic supplements. Aren't they cute?

Once the next piece of the puzzle was solved, the study was taken a step further and a third group of mice were supplemented with our friend Lactobacillus johnsonii. Lo and behold, these mice also exhibited diminished airway responses to allergens. It still is not known if the dust itself was the source of this beneficial bacteria or if components in the dust somehow altered the gut bacterial community to shift towards a population high in this particular species.

Although much more research is needed to prove that humans can benefit in the same way the mice did in these studies, these findings may one day lead to the development of probiotics for infants that could reduce the risk of developing allergic conditions. In the meantime, if you own a dog, you might just have a good enough reason to dust your house a little less often.