Recent reports of amputations and death highlight rare risk in dog saliva
Serious infection can happen without a bite or obvious scratches.
Article content
There’s nothing better then the exuberance of a furry friend — the jumping and the licking is their way of showing their love, but did you know that their saliva can cause a life-threatening infection?
You may have seen some of the recent headlines: “The shocking reason that this man’s legs and hands were amputated: A dog’s saliva,” and “Man killed and another loses legs after bacteria-riddled dog bites them.” These reports recount the horrific details of Capnocytophaga canimorsus, a common bacteria found in dog saliva that seeped into the bloodstream of unsuspecting animal-lovers, causing sepsis — also known as blood poisoning. Flu-like symptoms like fever, vomiting and abdominal pain worsen rapidly, sending victims to the ER.
“These patients are very sick and knocking on death’s door,” says Dr. Andrew Morris, an infectious diseases specialist in Toronto and medical director of the Sinai Health System-University Health Network Antimicrobial Stewardship Program. “The body is massively infected.”
It’s a very rare condition that happens most often to people who are asplenic, meaning they don’t have a spleen or their spleen doesn’t function normally, he says. People with compromised immune systems or those who suffer from alcoholism with poor liver function can also be at risk.
Morris has only seen about eight cases in 22 years of practice in his specialty.
“The truth is, it’s a ubiquitous organism, but in terms of incidents, it’s one per million people” who would have a severe reaction, Morris explains. “We don’t really have great statistics on prevalence.”
A national study in the Netherlands in 2010 found the incidence rate was 0.67 infections per million per year.
In extreme cases, the infection can lead to disseminated intravascular coagulation (DIC) syndrome where clotting and bleeding happen at the same time. While antibiotics can help stop the infection, it is a fast-developing threat that requires a suite of expert interventions — depending on the progression — from hematology, cosmetic surgery, kidney specialists and infectious diseases specialists.
Blood clots form throughout the body, blocking small blood vessels and the flow of blood to the extremities like hands and feet. The lack of blood and oxygen can lead to organ failure and causes tissues and muscles to die, sometimes resulting in amputation.
The U.S. Centers for Disease Control and Prevention reports that three in 10 people who develop a serious infection die. And Health Canada estimates that since 1976, when Capnocytophaga canimorsus was first described, approximately 200 human cases of the infection have been reported worldwide.
But for the most part, the bacterium is harmless, experts agree.
Capnocytophaga canimorsus is just one of the species of bacteria that live in the mouths of up to 86 per cent of dogs and 84 per cent of cats and rarely causes illness in pets, even if they are bitten by another animal, says veterinarian Scott Weese, a professor at the Ontario Veterinary College at the University of Guelph and director of the university’s Centre for Public Health and Zoonoses.
“It’s carried by healthy dogs, pretty much every dog. It’s not a concern for them and isn’t an issue for most people,” he says, adding there aren’t any signs that your dog is a carrier. “We can’t eliminate it from dogs so we should assume every dog is a carrier.”
Weese says the most important thing to know is that infection can happen following close contact with a dog and does not require overt scratch or bite injuries. And if you do have a bite or scratch, immediately wash the wound thoroughly with soap and warm water. If the wound is severe, or you’re at high risk for infection, consult a doctor.
“I think awareness is the key here,” says Weese. “There are safe ways to handle pets. So it’s just understanding what some of those risks are and talking to your vet can help with that. And the biggest thing is making sure your physician knows about any animal contact if you become ill.”
Bacterial infectious diseases from common household pets are frequently overlooked or misdiagnosed because physicians don’t typically ask about animal contact.
“Every mouth whether it’s a human or animal has varying levels of bacteria,” he says. “Every dog and every person has something in them that can cause serious disease in the right circumstance.”
There are various diseases human can get from dogs, ranging from common and mild like ringworm and tapeworm to rare concerns like rabies and Lyme disease from infected deer ticks they could carry. Overall, serious health problems from dogs are rare, says Weese.
Robert Pepper Jones, a veterinarian in Toronto, and a Healthing columnist, contracted an Methicillin-resistant Staphylococcus aureus (MRSA) infection from a patient that left him off work for months. While people usually get this antibiotic-resistant bacteria, pets can also get infected or become carriers.
“I was scratching my leg because I’ve got dry skin in the winter and that led to an infection of the artificial heart valve I had put in five years ago,” he says. “The bacteria appears to have been under my nails then in my bloodstream from scratching my legs.” He’s since had the artificial valve replaced.
“The point is really the rareness of the thing,” says Jones. “I was told I’m a pretty special case.”
He recommends annual checkups for your dog, along with parasite prevention protocols and vaccinations to keep them healthy – and owners protected, too.
Transmission of infection can go both ways. People can give their dogs a number of antibiotic-resistant bacteria, including MRSA, and viruses like COVID.
As Weese sees it, “People should be their own advocates for their health and the health of their pets, making sure their physician knows if they’ve had animal contact, especially if it’s a new animal or if they were just at a petting zoo. If people are high-risk — we usually group those into under five, over 65, pregnant, and compromised immunity — those people should have more specific discussions with their physicians.”
