Diarrhoea in nine-week-old puppies can be caused by several things. Your puppy might simply have eaten something it shouldn't have, or it could have a viral infection or parasites. You can treat your puppy's diarrhoea at home if it is mild, only last for a few days and is free of blood. Otherwise, it is important to contact a veterinarian to ensure your puppy is not infected with worms or other illnesses, which could include Trichomonas or Giardia.
Avoid giving your puppy anything to eat or drink for about 12 hours--although this time frame can be shortened if the diarrhoea begins to subside. Stop cutting off the water supply if your puppy begins to show signs of dehydration.
Monitor your puppy for signs of dehydration. These could include a loss of interest in physical activity, sunken eyes, dry gums and nose and a loss of skin elasticity.
Give your puppy Pepto-Bismol with a child's medication syringe every three hours for the first day of diarrhoea treatment. Give the puppy 1/2 teaspoon for every 4.54 Kilogram of weight. If the puppy weighs less than 4.54 Kilogram, give it 1/4 of a teaspoon.
Once the diarrhoea becomes less frequent and the puppy is interested in eating, offer your puppy a mixture of cooked rice and shredded chicken instead of regular puppy food. Place about two cups of water into the food bowl, then add one cup of cooked rice and small piece of chicken breast that has been finely shredded.
Give your puppy this food mixture for two additional days, then slowly begin to add its regular dog food in place of the rice and chicken, until the dog is eating regular dog food for every meal.
Contact your veterinarian if your puppy has severe diarrhoea that lasts for several days, the diarrhoea is accompanied by vomiting, or if your puppy appears to be severely dehydrated.