Capnocytophaga & Your Pet – TheReal Kiss of Death?You may have recently read a news story about a Wisconsin man who lost both ofhis legs and arms to an infection caused by the bacterium, Capnocytophagacanimorsus. This story caught the attention of news media because of the rarity ofthe infection and the severity of injuries. As this bacterium is commonly found inthe mouth of dogs and cats, many pet parents have been contacting veterinaryhospitals across the country because they’re worried about potentiallyexperiencing a similar fate. So, this week’s post is dedicated to raising awarenessof this infection. I hope you’ll share it with other pet parents to help spread theinformation. Happy reading!

Capnocytophaga – What is it?Capnocytophaga species live in the mouths of humans, dogs, and cats. They areconsidered normal oral flora. Capnocytophaga canimorsus is the species mostcommonly implicated in zoonotic infection, that is an infection transmitted froman animal to humans. Research has shown up to 74% of dogs and up to 57% ofcats carry C. canimorsus in their mouths. Happily, these gram-negative bacteriararely, if ever, cause illness in our companions. “Capno” refers to the bacteria’sability to survive in a local environment with high levels of carbon dioxide.

Microscopic appearance of Capnocytophaga canimorsus in a neutrophil. Imagecourtesy of the Journal of the American Society of Hematology.

Capnocytophaga – How can I becomeinfected?Capnocytophaga canimorsus may be spread to humans through bites, scratches,and/or after close contact with dogs and cats. The major mode of transmission isvia exposure of broken human skin to a pet’s saliva. For example, diabetichumans have been infected after allowing their dog to lick skin ulcers. Based onepidemiological studies in human medicine, 54% of human infections were causedby bites and 8.5% were caused by scratches. Just over a quarter of all humancases were reportedly caused simply by close contact with an animal.

Infection is considered to be opportunistic – this means the right conditions toexist have to exist for infection to occur. Humans with weakened immune systemsare most susceptible to Capnocytophaga canimorsus infection. Common reasonsfor folks having compromised immune systems include:

Individuals who don’t have a functional spleenCancer patientsHuman immunodeficiency virus (HIV) patientsIndividuals who drink alcohol excessivelyInfants and children less than five years of age

Interestingly, approximately 40% of people are seemingly healthy with no immunesystem issues. In this patient population, being male, having diabetes mellitus,and being older than 50 years of age have been identified as risk factors forinfection. Veterinarians have developed eye infections caused by C. canimorsusafter teeth fragments hit their eyes during dental procedures.

Capnocytophaga – What does infectionlook like?As mentioned earlier, humans actually have Capnocytophaga species in theirmouths. Those with weakened immune systems most commonly develop infectionsin tissues connected to the throat and mouth, most notably periodontal disease,respiratory tract infections, and eye infections.

Devastating hand infection caused by Capnocytophaga canimorsus. Imagecourtesy of Quirlycues.Life-threatening complications with this opportunistic infection occur when thebacteria gain access to the bloodstream. This phenomenon is called septicemiaand may trigger body-wide organ dysfunction and failure. Common sites ofcomplications in the body are:

Brain – infection causes meningitis, inflammation of the meninges orlining of the central nervous systemHeart – infection causes endocarditis, inflammation of heart vales

Bone – infection causes osteomyelitis, inflammation of bonesChest cavity – infection causes pleuritis, inflammation of the lining of thechest cavity

Symptoms of infection often manifest five days after exposure. Most commonly,infected individuals develop flu-like symptoms, including headache, fever, fatigue,skin rashes, muscle pain, difficulty breathing, and abdominal discomfort. Scarily,symptoms can progress to life-threatening proportions within 24 hours and ~30%with septicemia die from infection.

Capnotyphaga – How is infection treated?As Capnocytophaga canimorsus is a bacterium, treatment with an appropriateantibiotic is essentially. Thankfully, this bacterium is typically quite susceptible toa variety of antibiotics. If one develops compatible symptoms, has had been bittenor scra tched by a dog or ca t in the prev ious week , and has aweakened/compromised immune system, be sure to inform your physician of anysuch animal contact.

Capnocytophaga – Can infection beprevented?Remember Capnocytophaga canimorsus is considered a normal bacterium in themouths of dogs and cats. Furthermore, transmission from pet to human isuncommon, and illness is even rarer. Healthy dogs and cats carrying C.canimorsus do not require any testing or treatment. There is no evidence suchintervention would rid the bacterium from their mouths or prevent diseasetransmission.

Many ask if high-risk individuals should be allowed to have dogs and/or cats. Ingeneral, the answer is absolutely YES as long as diligent attention is paid toinfect ion control . Given the myriad benefits of pet-ownership,immunocompromised folks should discuss infection control measures with theirpersonal physicians. Most important, people should take steps to minimize bitesand scratches. Speak with your family veterinarian for helpful steps. If you’re pethas a behavioral problem, consultation with a board-certified veterinary behaviorspecialist may be uniquely helpful. Of course, please don’t allow dogs and cats to

lick your face or any areas with broken.

The take-away message aboutCapnocytophage infection in humans…Capnocytophaga canimorsus is commensal bacterium found normally in themouths of dogs and cats. With rare occurrence, infection from pet to human ispossible, especially in immunocompromised individuals. Symptoms are consistentwith the flu and can progress to life-threatening conditions within a day. Withoutprompt identification and treatment, severe organ dysfunction and death arepossible.

To find a board-certified veterinary behavior specialist, please visit the AmericanCollege of Veterinary Behaviorists.

Wishing you wet-nosed kisses,

CriticalCareDVM