I’m a microbiologist in a hospital laboratory.
DON’T let your animals lick you! Ever. Especially broken skin (rash, sore, etc.).
It is extremely dangerous. Animal mouths are NOT cleaner than human mouths.
We (humans and animals) all carry in our mouths a “normal flora” of bacteria. This normal flora includes varous Strep species, including Beta Strep Group A (yes, the one that causes Strep throat), and Streptococcus pneumoniae (yes, the one that causes pneumonia and menigitis). We also carry Haemophilus sp., Neisseria species (including N. meningitidis, the one that cause meningitis), yeast, Staphylococcus species, including MRSA (methicillin-resistant Staph aureus, the one that kills people), Coryneform bacilli, Eikenella corrodens, etc.
Animals carry some of this flora, including MRSA. In fact, pet vectors are one of the main sources of human MRSA infections. MRSA is no joke. If it gets into your bloodstream (sepsis), you can die.
In addition, animals carry different bacteria, including Pasteurella multocida.
As long as you have a normal immune system, the normal flora in your mouth or your pet’s mouth probably won’t hurt you.
We WANT these bacteria in our mouths. They protect us from infections. When you are given antibiotics, sometimes the antibiotic kills off the normal flora, and other nastier bacteria take over and cause a mouth infection (sores, inflammation, pain), or often yeast take over and cause the painful “thrush” infection in the mouth.
So be grateful for your normal flora.
But if you are immunosuppressed in any way, the organisms in your normal flora can gang up on you and cause an infection.
If you have a break in your skin, most of the time, your body’s immune system will still protect you from infection. But not necessarily. You get a person who is immunosuppressed, and introduce a bacteria, perhaps a doggie bacteria, into that broken skin, it’s possible that the bacteria could cause a localized infection of that skin, and it’s also possible for the bacteria to get into the bloodstream and cause sepsis.
Conclusion of Geek Lecture: Don’t put bacteria where they shouldn’t be put!