Infectious causes could be worms, protozoa, bacteria, and even viruses.
In a young puppy - I am VERY worried about another possible infectious cause - parvovirus...
Click here to read more on Parvovirus: CLICK HERE
What can we try at home and is over the counter to help?- You can try to offer small amounts of pedialyte for hydration and electrolytes. You can even purchase a dropper from your local pharmacy to offer the water/pedialyte mixture by mouth.- A calorie dense nutritional supplement such as nutrical (LINK HERE)- Another option would be baby food. If you are going to try this, please purchase baby food that does not have any ingredients such as garlic or onion.Many baby foods now will only have the ingredients of the item and water...for example chicken and water. But they will not have any other salts or seasonings. This is what you need. Just chicken and water or beef and water for example.
But if the signs do not resolve or worsen, I would recommend seeing a veterinarian.
Signs as you describe can quickly lead to severe dehydration and a low blood sugar!
When you go, please remember to bring in a stool sample to check for parasites.