A new meaning for ‘sick as a dog’

The last time I brought my dog in for her annual exam, the vet raised an eyebrow and double-checked the medical chart. “Same dog?” she asked, clearly surprised that Pepper’s recorded age did not match the glossy-coated ball of fur bouncing four feet off the floor in front of her. At 17, this spaniel-Chihuahua is a poster dog for ultra-longevity, and I’m delighted that she seems to be enjoying life with such gusto. But as I edge into my mid-50s, I must confess that my celebration of Pepper’s good health has sparked a much more selfish thought: Could my longtime companion’s well being bode well for my own?

Recent studies have supported the idea that pets are good for our health. Whether it’s their companionship or their insistence that we get off the couch and move (or both), research shows pets can lower blood pressure, improve our mood and even help us live longer. But I was wondering something different: Does a pet’s health reflect its human’s health status?

I asked Joseph Bartges, professor of veterinary medicine at the University of Georgia, this question. Bartges has been involved in the Centers for Disease Control and Prevention’s One Health initiative, an effort co-led by physicians and veterinarians to find commonalities in their work.

“As veterinarians, we often see pets who have the same health issues as their human companions or who are sentinels for a human health problem,” he said, attributing this to the fact that pets and owners share the same environment and spend so much time together.

“The trend of processed foods and everything that occurs with industrialization is making us both sick,” he added, citing the increasing numbers of conditions related to diet and lifestyle — such as diabetes, heart disease, autoimmune disease and cancer — in pets as well as humans.

Indeed, when researchers in the Netherlands studied pet-human pairs, they found that overweight dogs were more likely to have overweight owners. Because this was an observational study, it is impossible to pinpoint why this is the case, but data suggest that less time spent on walks was the greatest predictor of whether the pair would be overweight. Another study from Germany suggested that we tend to impose our own snacking patterns and attitudes about portion size and processed foods on our pets, which can influence how many calories they get in a day. Obesity is also a health issue for cats, but their body mass does not correlate as closely with that of their human companion. Perhaps this is because cats are more capable of exercising themselves.

“I see [pet-owner] connections all the time in the office,” said veterinarian Janet Foley, a One Health proponent who runs the Sonoma County Mobile Veterinary Hospital in Northern California. “But you have to be careful about how you raise these touchy issues. Luckily, I’m a people person, but it’s harder for vets who are just pet persons.”

Foley said she focuses on giving lifestyle advice for the pet. “But then I see a lightbulb go off [for the owner]. They are thinking ‘I should do that, too.'”

Allergies, emotions

Our pets can offer other insights into our health issues.

Take your chronic sniffles, for example. If you suspect they might be caused by allergies, you might want to see whether your symptons are shared by the family dog. According to a recent study from Finland, urban living, small family size, and disconnection from nature and other animals was linked to a higher risk for allergy in humans and their dogs. (Allergic dogs get canine atopic dermatitis, which is a kind of doggy eczema.) On the other hand, dogs and their owners who lived on a farm or in a household with many animals and children, or regularly visited a forest, were protected from allergies.

Though there is still much to be discovered about this “farm effect,” many immunologists are convinced microbes play an important role. From birth onward (and possibly in utero) the combinations of microbes found in rural and natural environments seem to train the immune systems of puppies and kids and make them less hyper-reactive. Bolstering this idea is the discovery that the skin microbiome on dogs and humans who suffer from allergies differs from their healthy counterparts.

Foley mentioned another way pet allergies might give us a new perspective on our personal health. Feline asthma, she explained, is often triggered by tobacco smoke. So whenever she makes this diagnosis, she’ll ask whether there is a smoker in the home. “Sometimes a wheezy cat can offer someone the insight they need to see that smoking is bad for their own health,” she said.

Companion animals also provide insight into our mental well being and the strength of our social interactions. “There are some indications of dogs being able to understand the mental state and emotions of their caregiver,” said Therese Rehn, a small-animal researcher at the Swedish University of Agricultural Sciences. One of her studies found that people with an avoidant attachment style — meaning they run away from their feelings — often have dogs who separate from their owner when faced with a social stressor. “They don’t regard their owner as a safe haven,” she said. A recent study reported in Nature supports the notion that our pet’s emotional state can mirror our own. Researchers measured hair cortisol levels (an indicator of chronic stress) in dog-human dyads and found a strong degree of interspecies synchronization. In general, this “emotional contagion” seemed to flow from humans to their dogs, and not vice versa.

According to Bartges, feline idiopathic cystitis is an example of a vexing animal health issue that can give us a peek into our own psychology. Cats with idiopathic cystitis don’t have a urinary tract infection, but they have blood in the urine, fuss a lot, frequently use the litter box and urinate around the house. (With the exception of the litter box issue, this sounds exactly like interstitial cystitis, a health issue I see often in my female human patients.)

Dual treatment

“Idiopathic cystitis is brought on by stress in the household, and owners of cats with idiopathic cystitis are usually stressed about having cats with idiopathic cystitis and it just feeds on itself,” Bartges said. His research indicates that simply treating the owner’s anxiety by giving them a sense that they are being heard can often make the cat’s symptoms disappear. “Here is a case where treating the owner is just as important as treating the pet,” he added.

I might be guilty of confirmation bias — interpreting evidence in a way that confirms my hypothesis — but each veterinarian I spoke with validated the idea that a pet’s health can often reflect our own: anxiety, obesity, allergies, gastrointestinal infections and even insomnia are all disorders that can exist in pet-owner dyads.

In fact, given all these associations, I am asking all my patients whether they have pets at home and, if so, how those pets are faring. I am also asking patients whether they get personal health pointers (directly or indirectly) from their vets. The number of times I hear “Why yes!” is amazing. One patient credited his vet with solving his long-term sleep problem. (“He told me to treat my dog’s fleas, get rid of her noisy collar and get her out of the bed.”) Another said that it was her vet’s gentle persistence that got her to quit smoking,

Kate Hodgson, a veterinarian at the University of Toronto’s medical school, has written extensively about integrating the One Health approach into a medical visit. She recommends that primary care physicians routinely ask about family pets and consider collaborating with the family veterinarian, as long as patients give their permission.

Since our last visit to the vet, I’ve noticed that Pepper is developing a cataract. It might be time for me to go get my eyes checked, too.