Diarrhea is not a disease itself but rather a symptom that something is not right with your dog's health or gastrointestinal system.
Many dogs, like humans, may occasionally suffer from an acute bout of diarrhea. If your dog is well and has no other symptoms other than a frequent loose bowel motion there is probably no cause for immediate alarm and you can treat it at home. There are many causes for diarrhea, for example your dog may have eaten something disagreeable. Other causes could include a sudden change in diet, food allergies, worm infestation or viral or bacterial infection.
If your dog has chronic diarrhea then medical advice should be sought. Always check with your vet if diarrhea is severe or persistent.
Diarrhea can be life threatening.
If it reoccurs...please see your Vet so you can find out what the underlying problem is.