Is Pine Bad For Dogs. There are several examples of dogs that eat pine needles and then have their intestines puncture from the inside. Pine sap is bad for dogs.

While the exact mechanism of toxicity is unknown, some dogs develop an upset stomach after eating pine wood. The needles can puncture or irritate the lining of your dog's stomach, and the oils can irritate the mucous membranes. This is especially true with pine needle mulch, as the pine needles can actually puncture the stomach lining if ingested.