Researchers seek secrets of the microbes that colonize the skin of dogs, cats and humans
By Kim Campbell Thornton
Andrews McMeel Syndication
Do the bacteria and other microbes living on your pet’s skin affect skin health? A professor of veterinary pathobiology at Texas A&M College of Veterinary Medicine is studying the effects of the skin microbiome -- the community of microscopic “bugs” that sublet space on the epidermis of cats, dogs, humans and other animals.
Aline Rodrigues Hoffmann, DVM, was intrigued by papers she read a few years ago on the human skin microbiome. She immediately began thinking of ways to study the variety of organisms that inhabit dog and cat skin, and how they might affect or promote pet health.
What do the millions of microorganisms on skin do? They’re commensal, meaning they contribute to health and well-being through complex interactions with their host -- your dog, cat or yourself. The skin microbiome helps to modulate immune responses by influencing T-cell function and inflammatory response and promoting protective immunity against pathogens. It’s also a factor in susceptibility to infection and response to treatment for skin diseases.
Bacteria, fungi and viruses are among the complex population of microorganisms that colonize normal skin. They contribute to skin health and help to prevent potential pathogens from moving in and taking over.
“Our ultimate goal was to find the commensal microbes, the beneficial microbes, that could potentially be used as a probiotic,” she says. “This has already been done in the gastrointestinal tract. In the skin microbiome, we are still taking baby steps.”
Studying the skin’s microbiome is not as straightforward as studying bacteria in the gut. Skin and hair are exposed to the environment, and factors including temperature and moisture may also influence which microorganisms live on the skin. In dogs and cats, for instance, Hoffmann found that fungi that are normally found in the environment are also found in large numbers on pet skin.
That may be one of the reasons why some humans have allergic reactions to pets. Some of the common environmental fungi found on dogs and cats are the same ones that people tend to be allergic to.
Interestingly, people who live with dogs have similar microbiota to their dogs. The same isn’t true for people who have indoor cats. That’s probably because those cats don’t have the same access to the outdoors as dogs, so they are less likely to influence the diversity and makeup of the skin microbiome of the humans with whom they interact.
Different areas of a healthy dog’s body have different microbial populations. Areas with hair such as the groin, the ears or between the toes have greater microbial diversity than mucosal surfaces such as lips, nose, eyes and ears.
Some cat breeds have skin microbiome differences as well. Hoffmann presented a study in April at the North American Dermatology Forum showing that Cornish rex and Devon rex cats had higher populations of Malassezia yeast than other cat breeds. And cats with allergies have a larger population of Staphylococcus species of bacteria. Over the entire body, allergic cats tend to have a less diverse population of microorganisms than healthy animals.
With rare exceptions, there’s no reason to fear exposure to a pet’s microbiota.
“We no longer want to eliminate those pathogens or microbes,” Hoffman says. “We want to make sure they are in balance.”
Figuring out what that balance should be is the next step. So is rethinking the use of antimicrobial medications or figuring out how to use them more effectively.
“I think we are now finding out we don’t need to treat as aggressively as we were doing before,” she says. “Hopefully that will ultimately reduce use of antibiotics and all the problems that we see with it.”
Meat is a must
in feline diet
Q: Why is it so important for cats to have meat in their diet? Humans and dogs can get by without it.
A: Cats come with a special label: obligate carnivore. Its meaning is just as it sounds: Cats must eat meat if they are to survive and thrive.
An essential amino acid called taurine is one of the reasons that meat is so important to a cat’s good health. The feline body can manufacture some amino acids (which you may recall from grade school as the building blocks of proteins), but the essential amino acids, such as taurine, which is found only in animal tissues, must be added to a cat’s diet.
Taurine is what powers excitable cells -- those that are part of a nerve or muscle. The brain, the skeletal muscles, the heart, even the retina of the eye are all excitable tissues and need taurine to function. A cat’s heartbeat, vision, movement and brain function are all dependent on taurine.
Cats who don’t get enough taurine can develop a type of heart disease called dilated cardiomyopathy (DCM). It was just 30 years ago that Paul Pion, DVM, discovered the link between DCM in cats and a diet deficient in taurine. Turns out that taurine is largely destroyed by cooking, so pet food manufacturers had to readjust their recipes to ensure that cats received enough of the essential amino acid in their diet. People who feed cats a homemade diet must be sure to supplement the food with taurine.
Other health problems related to taurine deficiency include reproduction problems in female cats (known as queens); reduced growth in kittens; and central retinal degeneration, which can lead to irreversible blindness. In fact, in Pion’s 1987 study, 27 percent of the cats in the study also had central retinal degeneration. -- Dr. Marty Becker
Do you have a pet question? Send it to firstname.lastname@example.org or visit Facebook.com/DrMartyBecker.
risk to pets
-- Summer and fall are foxtail season. The grass awns with the spiky bristles look harmless, but if the barbed end gets caught in a dog’s coat, it can work its way into the skin and cause painful and serious infections. The best way to deal with foxtails is to avoid them, but if that’s not possible, inspect your dog thoroughly immediately after outings, from head to tail to between the toes. If you find a foxtail that can’t be removed easily, take your dog to the veterinarian. The foxtail may require surgical removal followed by a course of antibiotics.
-- Think your pet is a work of art? If you live in Orlando, Florida, you can purchase a pet membership and “exhibit” him at the Mennello Museum of American Art’s sculpture garden at regular pet-friendly events. Dogs, cats and birds are eligible for the $25 memberships and may visit the sculpture garden during events such as picnics, brunches, Yappy Hour and October’s Howl O’Woof, with costumes and trick-or-treating. Pets can’t go indoors to visit the collections, but they are likely to enjoy the walking paths and live oak trees found in the sculpture garden. Just don’t let them mark the statues.
-- Cyrano L. Catte II has two firsts to go along with his illustrious name. Not only is the Virginia feline the first cat to receive stereotactic radiation therapy to treat his bone cancer, he’s also the first cat to undergo a total knee replacement -- with a 3-D-printed prosthesis. Denis Marcellin-Little at North Carolina State University performed the knee replacement surgery. He worked with the university’s industrial and systems engineering professor Ola Harrysson to design the implant. One of the difficulties was making it small enough to be used with the 26-pound cat, but now Cyrano can comfortably use his leg and joint. -- Dr. Marty Becker, Kim Campbell Thornton and Mikkel Becker
ABOUT PET CONNECTION
Pet Connection is produced by a team of pet-care experts headed by "The Dr. Oz Show" veterinarian Dr. Marty Becker and award-winning journalist Kim Campbell Thornton. They are affiliated with Vetstreet.com and are the authors of many best-selling pet-care books. Joining them is dog trainer and behavior consultant Mikkel Becker. Dr. Becker can be found at Facebook.com/DrMartyBecker or on Twitter at DrMartyBecker. Kim Campbell Thornton is at Facebook.com/KimCampbellThornton and on Twitter at kkcthornton. Mikkel Becker is at Facebook.com/MikkelBecker and on Twitter at MikkelBecker.