My 15 year old small breed dog suddenly started defecating through the night; is it because of his age?

No diet changes? No changes in his schedule? Are the stools normal?

If everything else is unchanged and his health, appetite, and behavior are the same, it may be senility. But I’d have him checked out at the vet to be safe – that’s a pretty geriatric age.

Probably. That’s what happens to people, too.

There has been a bit of mucus in his stool, and yes, there has been a change in diet.

It’s hell getting old….

Fifteen is pretty darned old even for a small breed dog. Bottom line is when we meat bags become ancient our systems just don’t work the way they did when we were kids.

Any advice on what I can do?

If there was a diet change, then I suspect it’s got a higher fiber content or some other change that’s thrown his system a bit. It may resolve with a little time, or you may need to gradually switch back if he just doesn’t tolerate it well.

Check his hydration, pinch a little skin together, gently, and see how elastic his skin is. And a visit to the vet is probably good.

@syz would that lead to a “mucousy” stool?

Is it mucus or mucous? My brain is fried.

It’s possible; he could have some mild intestinal inflammation.

I made a vet appointment for tomorrow.

Yes, a visit to the doggy doc is in order.
I had a small breed ( Dachshund/Schipperke X ) years ago that became urinary incontinent and turned out she had a tumor pressing on her bladder. Get him checked out ASAP to be on the safe side.

My dog cannot digest high fatty foods. It will start with mucus in the stools and sometimes it will end up with him vomiting bile as well. He may be showing signs of problems with his pancreas.
For now I would suggest taking some chicken and boiling it and giving him rice and chicken. You can also try to do the same with boil beef. Strain all the fat out. Boil the rice in plain water as well. If you go this route you may need to feed your dog more than usual. The low fat will leave him feeling hungry in hours. I had to feed my dog 3 times a day vise once a day and he still lost weight. We caught his problem early so he only needed to be on the diet for 3 weeks and then we changed his food to eckanuba which is pretty low fat. He was diagnosed years ago but has been doing fine. But I can always tell when someone has given him too many treats or people (fatty) food. He will vomit soon after and have loose mucusy stools.
Do take him to see a vet. Other complications can come from pancreatic disease if it turns out to be the problem.

@Pandora

Yes, the pancreatitis thing, OMG! A big hound of mine was on IV’s for 2 days after swiping a 2lb. Pork roast off the kitchen counter. He was not a happy puppy, and, it cost about $600 to save him. Baaad, very baaad dog! haha

My Pom is only 10yrs old but he gets yucky poop anytime he eats something more than his regular food and sometimes will barf up yellow foam. Tell us what your vet says.