Welcome to Just Answer. My name is Jane. I have been involved professionally with dogs in the healthcare and behavioral fields for over 20 years. I’ve worked as a Vet Assistant and Behaviorist and have extensive experience in dog reproduction, as a breeder, for even longer than that.. Canine behavioral issues and training are also my specialties. It will be my pleasure to work with you today.
if it was a relatively normal length for a piece of dental floss ( a few inches long ) then it likely will pass through without any problems. However, I would recommend feeding a couple of pieces of bread depending on the size of your pup to hopefully wrap around the floss to keep it together better. You will have to monitor your pup and look for the floss to be expelled in the fecal matter. I caution you NOT to pull on it if it only partially exits the rectum. If you pull you might injure the bowels. Instead just cut any piece hanging out at the rectum so the dog will not try and grab it either.
If it is more of a ball of dental floss then you might have to worry more about an obstruction. I'll give you as site on obstructions but watch for a loss of appetite, vomiting and possible inability to defecate that might occur with an obstruction and have your pups seen if that occurs. Most objects pass within 72 hours.
Now if it just happened in the last hour or so, you might induce vomiting to try and retrieve the piece and eliminate any possibility of damage to the intestines or an obstruction. Read about inducing vomiting here:
If it is a longer piece but not in a ball, it might become lodged in the intestines and end up damaging the intestines. So be sure to monitor your dog closely if it is a longer piece if inducing vomiting does not bring it up.
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