Pencil-Thin Stools in an 8-Year-Old Male Dog

Stools that are consistently thin or ribbon-like can mean something is narrowing the passage or pressing on the colon or rectum. In an older male dog that isn't neutered, a common cause is benign enlargement of the prostate. Other causes include enlarged lymph nodes, a perineal hernia, a narrowing (stricture) of the rectum, or a mass.

Because it's been going on for a while, please book a vet visit even though he seems well. A rectal exam can feel the prostate and rectum, and your vet may suggest X-rays or an ultrasound. Many of these causes are very treatable: benign prostate enlargement in an intact dog is often managed with neutering or medication. If he is neutered, an enlarged prostate needs prompt investigation.

See dog constipation symptoms for more on thin or ribbon-like stools.

This is general information, not a diagnosis. Please follow your own vet's advice.