diarrhea or liquid stools

Question
are there any over the counter remedies for this for dogs?

Answer
You first need to know what's causing the problem. Have your dog checked for parasites and other things that can cause this symptom, such as parvo, ecoli, campylobacter etc.
Barring all of those you can give your dog immodium. You also need to change the diet to brown rice boiled in unsalted chicken broth. boneless skinless chicken. unsweetened canned pumpkin, a boiled egg shell and all, plain all natural yogurt, and acidophulous capsules.
Watch for lethargy, fever, symptoms of pain, general not feeling well and fever, or bleeding. Those are things that should red flag you to take your dog to the vet asap
good luck
Cindi