Dogs and Germs
Dogs and Germs Header

Your dog is your trusty sidekick. That tail-wagging, sofa-snoozing, stick-fetching bundle of unconditional love is so cute you could kiss him – but should you? After all, dogs have some questionable hygiene habits: They’ve been known to scarf up food from the floor, enthusiastically scatter the contents of the trash can, and even lap up toilet water.

But how germy are they really? To find out how much bacteria your canine companion might host, we recruited six dogs (along with their obedient owners) and swabbed six types of surfaces: each dog’s mouth, bowl, and toy and each owner’s mouth, fork, and cellphone. We then sent the samples to an independent lab to determine the amount and types of the bacteria present. What’s the verdict? Keep reading before you put your lips on that adorable snout.

Who’s Cleaner: You or Your Dog?

Dogs/Humans Hygiene

It’s the ultimate germ showdown: dog versus owner. The bacteria test results are in … and they’re surprising! You know that old adage about a dog’s mouth being cleaner than a human’s? In our tests, the owners’ mouths actually did host 1.4 times more creepy-crawlies than their dogs’ lolling tongues. Human mouths actually averaged the highest number of viable bacteria cells among every surface 7.5 million colony-forming units per square inch (CFU/sq in).

Home to 6.5 million CFU/sq in, the dog toys were more than twice as germy as the human’s favorite “toy” (aka the cellphone). Same goes for the dog dish: With 6.2 million CFU/sq in, it was twice as bacteria-ridden as the owner’s fork. Thankfully, germs from dogs infrequently transfer to their owners, according to the CDC.

Germ Breakdown, by Surface

Now that we’ve looked at the bacteria levels, let’s dig into the breakdown found on the six surfaces we tested. The types of germs ranged from benign to potentially harmful. Gram-negative rods – which tend to be harmful to humans – dominated all three owner surfaces. The worst offender? The cellphone. The dogs’ surfaces had lower proportions of these nasty germs. (And just think how many trips to your face that warm cellphone takes in any given day.)

Except their mouths, where mostly harmless gram-positive rods dominated, the dogs’ surfaces contained a fairly even breakdown of bacteria. Interestingly, the dog toys, dog bowls, and human mouths were the only surfaces containing bacilli (which can cause infections and food poisoning).

All six surfaces hosted gram-positive cocci, which are linked to skin infections, pneumonia, and blood poisoning. The human mouth had the largest proportion of this germ, followed by the dog toy. Surprisingly, the forks were the only surface that contained yeast (which could cause skin infections under certain conditions).

The takeaway? We don’t recommend that you put your lips to any of these surfaces – but based solely on the amount of bacteria on each, chances are you’d be better off smooching your dog’s mouth rather than kissing your cellphone.

Germs Unleashed: People, Pets, and Toilets

Germ comparison

Next, we looked at how the six surface types we tested stacked up to other common surfaces – and the results are eye-opening to say the least! The surfaces were many times germier than your toilet seat, faucet handle, kitchen sink, bathroom door knob, refrigerator handle, and a tennis ball.

Whether they belong to people or pets, mouths are an ideal spot for bacteria to thrive because they’re moist, warm, and dark. In addition, food is introduced frequently, and the remnants can also get caught in teeth. However, though germs love moisture, they can also thrive on dry surfaces for long periods of time.

Germ Breakdown: Dogs vs. Owners

germ breakdown: dogs vs. owners

Totaling the number of each germ type present on every surface yielded an interesting breakdown. Nearly half of the germs on the people’s surfaces were the nasty gram-negative rods, which can be harmful. These comprised only 30 percent of the bacteria on the dogs’ slobbery surfaces.

The dogs’ surfaces had a proportion of bacilli nearly triple that of the humans’ surfaces. (This type can potentially cause infections.) The pets’ surfaces also had a higher proportion of the mainly harmless gram-positive rods – and none contained yeast.

The Germiest Pooch on the Block

germiest dog by breed

To test all these germs, we relied on six helpful canine assistants of six different breeds. Who had the most germs thriving in their mouths and on food dishes and toys? Our Cavalier King Charles Spaniel had 27 million CFU/sq in – nearly quadruple the germs of our cleanest pup, the West Highland White Terrier. The husky-Labrador retriever mix was the second-germiest, with 24 million CFU/sq in, while the Manchester terrier and pug came in fourth and fifth respectively.

Putting a Leash on Germs

As our results showed, dogs’ mouths, toys, and food dishes certainly do host an array of bacteria – but so do humans! If your dog is a licker, you don’t need to panic. There are a few steps you can take to prevent your dog from hosting extra germs.

  • Wash your hands frequently using warm soap and water – particularly after handling pet food or treats, which can harbor Salmonella.
  • Schedule regular veterinarian visits, and keep your dog up to date on vaccinations.
  • Brush those canine teeth regularly.
  • Choose stainless steel or ceramic pet dishes, as plastic bowls can get scratches that host bacteria.
  • Frequently wash your dog’s bedding, toys, and food and water dishes.  
  • Keep your pet out of the trash can and away from wild animals.

Although our results were interesting, don’t let them change the way you feel about your pooch. You should still dish out plenty of pats, belly-rubs, and hugs. After all, the dog-human relationship is based on unconditional love – germs and all.


An independent lab performed all laboratory testing and samples were taken from the mouths, forks, cellphones, dog bowls, and dog toys belonging to six dog owners and their dogs. We tested for gram-positive rods, gram-positive cocci, gram-negative rods, bacilli, and yeast. All numbers presented in this study are an average of all like samples taken.


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