Puppy Straining, With Constipation Alternating With Loose Stools

Straining with alternating hard and loose stools usually points to irritation of the large intestine (colitis), or to constipation with liquid stool leaking around a firmer mass. In a puppy, common triggers are something he's swallowed (rawhide pieces, bones, toys, plants) and intestinal parasites.

Because he's a young rescue, ask your vet to check a stool sample for parasites, even if he's been dewormed. Call the vet now if he's straining without producing anything, or if he vomits, stops eating, seems lethargic or has a painful belly, since swallowed objects can cause a blockage. Keep fresh water available and avoid treats and chews until he's back to normal.

See dog constipation symptoms, which explains why constipated dogs can seem to have diarrhea.

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