Senior Lab Drooling, Straining and Passing Bright Red Blood
Straining with watery stool and a little bright red blood usually points to colitis. In a 10-year-old dog, it's worth also checking for problems such as an anal gland issue or a growth in the rectum.
The drooling makes us a little more cautious: it can mean nausea, something stuck in the mouth, or, in a large dog, early bloat. If she retches without bringing anything up, her belly swells, she becomes weak or her gums look pale, go to an emergency vet rather than waiting until Monday.
See blood in dog stool for when bloody stool is an emergency.
This is general information, not a diagnosis. Please follow your own vet's advice.