Loose motion in dogs can be due to stress, anxiety, bacterial,viral, fungal, and parasitic infection of gastrointestinal tract, food allergy, eating garbage, changes in diet, symptoms of some other illnesses, lymphoma, cancer and side effects of many medicines. Treatment of canine diarrhea depends upon underlying cause. Diagnosis may require blood tests, fecal tests or x-ray. After proper diagnosis your vet will be in position to suggest any treatment. So, take your dog to vet for proper diagnosis and treatment.