After knee replacement, dog’s wound lick is too ick

DEAR DR. ROACH: I had bilateral knee replacement two months ago, and I’m concerned about infections. My doctor wants me to take an antibiotic before any dental procedure, including cleaning, which I will do. I also have a dog that loves to lick any cuts, especially if there is some blood to lick. What are the chances of a prosthesis becoming infected? Can one’s immune system fight off any bacteria that gets into the bloodstream? — S.S.

ANSWER: I often have heard that dogs’ mouths are clean, but that is not the case. Bacteria from a dog’s mouth can indeed cause an infection in any kind of open wound, even a small cut or scratch. Our immune system is normally very good at fighting them off, and I rarely see significant infections caused by the germs in a dog’s mouth (cats, monkeys and humans tend to be much worse).

However, in an artificial joint, such as after a knee or hip replacement, the immune system can’t effectively fight off infection, which is why your doctor recommended the antibiotic before a dental cleaning. They often cause some bacteria to transiently enter the bloodstream. Bacteria can enter the blood through an infected wound as well.

The chances of a joint infection after a dental cleaning or a cut, with or without a dog, are small, but the event is devastating. Keep the dog away: Cleanse any wound thoroughly with mild soap and water — but no harsh disinfectants like peroxide, which do more harm than good. Apply some antibiotic ointment (such as triple antibiotic) and cover with a clean bandage.

DEAR DR. ROACH: Would you give me information on blocked bowel movements? I had a colonoscopy two years ago, and they said they couldn’t complete the procedure because of bowel blockage. I am 86 years old and don’t want a colostomy. — H.I.

ANSWER: A bowel blockage or obstruction can be partial or complete. There are numerous causes of bowel obstructions. Cancer is the first one I think of, as it’s the worst case, but others include a volvulus (twisting of the bowel on its axis) and intussusception (folding in on itself like a sock).

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