When a dog licks a minor abrasion or cut, the dog’s mouth is not sterile. Dog saliva carries numerous microorganisms that can enter the compromised skin barrier of an open wound, introducing a potential for complication. Understanding the contents of dog saliva and the potential health risks is the first step toward appropriate action and care.
What Dog Saliva Contains
Dog saliva is a complex mixture containing more than 600 different types of bacteria, many of which are part of the animal’s natural oral microbiome. Key species include Pasteurella multocida and Capnocytophaga canimorsus, which are typically harmless to the dog but can be pathogenic to humans. Studies show that a high percentage of pet dogs, sometimes over 80%, harbor Pasteurella in their saliva.
Canine saliva also contains proteins and enzymes, such as lysozyme, which possess mild antimicrobial properties. While it includes growth factors that may theoretically aid in healing, these benefits are modest and outweighed by the risk of infection.
Dogs often lick things other than themselves, meaning their saliva can also carry environmental contaminants. These contaminants include soil particles containing bacteria like Clostridium tetani, the agent that causes tetanus.
Potential Infections and Health Risks
The most common infection risk comes from Pasteurella multocida, which is frequently found in dog mouths. When Pasteurella enters a break in the skin, it can cause cellulitis, a localized infection often characterized by rapid onset within 24 hours. Symptoms include tenderness, swelling, warmth, and redness around the wound site.
A more serious, though rare, threat is posed by Capnocytophaga canimorsus, a bacterium present in the saliva of most dogs. While infection is uncommon in healthy individuals, it can lead to a rapidly progressing, life-threatening systemic illness like sepsis.
This severe infection can cause serious complications, including organ failure, disseminated intravascular coagulation, and gangrene, sometimes requiring amputation.
The risk of infection increases significantly if the break in the skin is more than a superficial scrape, such as a deep cut or puncture wound. Even without a bite, dog saliva contacting non-intact skin has been linked to infections. While the overall risk from a minor lick on an abrasion is low for a healthy person, the potential consequences warrant caution.
Immediate Steps After a Lick
If a dog has licked an open cut or scrape, the immediate goal is to physically remove the saliva and any introduced microorganisms. Begin by washing the area thoroughly with soap and running water for several minutes; this mechanical action is highly effective at reducing the bacterial load. Gently scrub the wound surface to ensure debris is flushed out, then rinse completely to remove all soap residue. Following the cleaning, apply an over-the-counter antiseptic product to help prevent bacterial growth. Once cleaned and disinfected, cover the wound with a sterile bandage or dressing to protect it from further contamination.
Recognizing Signs That Require Medical Care
After the initial cleaning, monitoring the wound for signs of infection is necessary, as symptoms can take anywhere from one to ten days to manifest. Localized signs include increasing redness, swelling, and warmth that extends beyond the wound edges, severe pain, or the presence of pus or discharge. Systemic infections, especially from Capnocytophaga canimorsus, require immediate medical attention and may present with fever, chills, vomiting, or diarrhea. Individuals with compromised immune systems, those without a spleen, or people with diabetes should seek prompt medical advice even for minor exposures, as they are at a higher risk for severe illness.