
This exactly like our old Lab girl who began to experience fecal incontinence early last winter at age 13. In our case we already knew she had a bad back; invertebral disk disease and significant spinal spondylosis (sp?). Jet is on pain medication for her back for the rest of her life. She gets a 2.5 mg dexamethasone every other day. Our Vet says the fecal incontinence is due to a loss of sensation in her nether regions so that the poop is upon her before she has a chance to prepare for it. Whether the loss of sensation is due to her back condition or to the medication is something I did not think to ask but the incontinence began sometime after the medication began. It does seem logical to me that medication to control the sensation of pain might also dim the other sensations. But that is a guess on my part.
Our Vet has suggested we give Jet an antidiarrheal, specifically he recommended Imodium ( I buy a generic). The idea behind this is that it will help bulk up her stools a bit so she will be better able to feel them and it does help. Gives her just a bit more time to react. We only give her one half a tablet once a week.
Perhaps you could ask your Vet about your boy's back and if the Imodium might help both of you too.