There is an ancient belief – supposedly dating back to the Egyptian times – that dog saliva can cure or help heal human wounds. Interestingly, this belief is widely held to this day.
On the flip side, the Centers for Disease Control and Prevention (CDC) warns pet companion parents:
- that pets should not lick you after they eat (if they do, wash the area afterward),
- to discourage pets from licking your wounds; and,
- to avoid pet licks if you are positive for SARS-CoV-2 – the coronavirus that causes COVID-19.
Many of us companion pet parents think to ourselves, “You try to stop the love.”
It’s complicated.
According to Floyd Dewhirst and his research colleagues, a dog’s saliva has approximately 400 different kinds of bacteria. Of course, that’s just what they have identified.
Many of our readers may know of a study that showed that a dog’s saliva has antibacterial properties. Read the text closely:
“Canine saliva was tested for its bactericidal effects against pathogens relevant to the presumed hygienic functions of maternal grooming of the mammary and anogenital areas and licking of wounds. Both female and male saliva were bactericidal against Escherichia coli and Streptococcus canis but only slightly, and insignificantly, bactericidal against coagulase positive Staphylococcus and Pseudomonas aeruginosa.”
That’s intraspecies. That’s a dog licking another dog – not licking a human, and only a few bacterial types were assessed. However, there is a documented human case of bacteremia (the presence of bacteria in the bloodstream) from Streptococcus canis following a dog bite.
But, that’s a bite and not a lick exposure. Indeed, several studies have looked at human bacterial infections caused by dog bites. Dogs are our best friends, right? Our dogs shouldn’t bite us and cause puncture wounds that may cause infection.
Indeed, unwounded, immunocompetent humans have been documented, albeit rarely, to develop sepsis with Capnocytophaga canimorsu from a companion dog’s licking. This bacterium can also cause meningitis.
What other bacteria does dog saliva harbor that may be harmful to humans? Here are a couple of examples:
- Pasteurella – can cause soft tissue infection, pneumonia, and sepsis.
- Campylobacter – can cause diarrhea and many pet store puppies had an antibiotic-resistant strain a couple years ago that infected humans.
Don’t misunderstand us, we think that some of the bacteria in dog saliva may have healing or probiotic properties? Yes; it is possible, there is only about a 15 percent overlap in similar oral bacteria between dogs and humans.
If you are not immunocompromised, do not have a chronic disease or face wound, nor are elderly, companion pets can lick you, so long as you follow the CDC’s guidelines. We are already washing our hands for 20 seconds due to potential or actual SARS-CoV-2 exposure. Thus, washing your face for 20 seconds after some dog love is easy!
References
Coronavirus (COVID-19) Frequently Asked Questions. Centers for Disease Control and Prevention, 20 Nov. 2020, https://www.cdc.gov/coronavirus/2019-ncov/faq.html#Pets-and-Animals.
Cuffel, Grace. “Does Dog Saliva Have Healing Powers?” SiOWfa15: Science in Our World: Certainty and Controversy, Pennsylvania State University, 21 Oct. 2015, https://sites.psu.edu/siowfa15/2015/10/21/does-dog-saliva-have-healing-powers/.
Dewhirst, Floyd E et al. “The canine oral microbiome.” PloS One vol. 7,4 (2012): e36067, doi:10.1371/journal.pone.0036067, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0036067.
Dodds, Jean. “Outbreak of Antibiotic Resistant Campylobacter Bacteria Linked to Pet Store Puppies.” W. Jean Dodds’ Pet Health Resource Blog, Tumblr, 23 Sept. 2018, https://drjeandoddspethealthresource.tumblr.com/post/178379834351/antibiotic-resistant-bacteria-outbreak-pet-store#.X8fTpGhKjIU.
“Dog’s Saliva Caused Bacterial Infection Leading to Amputations.” MPR, Haymarket Media, 3 Aug. 2018, https://www.empr.com/home/news/dogs-saliva-caused-bacterial-infection-leading-to-amputations/.
Elliott, David R et al. “Cultivable oral microbiota of domestic dogs.” Journal of Clinical Microbiology vol. 43,11 (2005): 5470-6, doi:10.1128/JCM.43.11.5470-5476.2005, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1287777/.
Hart, B L, and K L Powell. “Antibacterial properties of saliva: role in maternal periparturient grooming and in licking wounds.” Physiology & Behavior vol. 48,3 (1990): 383-6, doi:10.1016/0031-9384(90)90332-x, https://pubmed.ncbi.nlm.nih.gov/2125128/.
Mader, Naomi et al. “Being Licked by a Dog Can Be Fatal: Capnocytophaga canimorsus Sepsis with Purpura Fulminans in an Immunocompetent Man.” European Journal of Case Reports in Internal Medicine vol. 6,10 001268. 9 Oct. 2019, doi:10.12890/2019_001268, https://www.ejcrim.com/index.php/EJCRIM/article/view/1268/1808.
Pet Food Safety. Centers for Disease Control and Prevention, 27 Sept. 2017, https://www.cdc.gov/healthypets/publications/pet-food-safety.html.
Taniyama, Daisuke et al. “Human case of bacteremia caused by Streptococcus canis sequence type 9 harboring the scm gene.” IDCases vol. 7 48-52. 20 Jan. 2017, doi:10.1016/j.idcr.2017.01.002, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5295620/.
Wilson, James P et al. “Lick of death: Capnocytophaga canimorsus is an important cause of sepsis in the elderly.” BMJ Case Reports vol. 2016 bcr2016215450. 30 Jun. 2016, doi:10.1136/bcr-2016-215450, https://casereports.bmj.com/content/2016/bcr-2016-215450.info.