My "Sheltie" always has a poopy butt. What are the recommended products for a drier stool? We have him groomed regularly to eliminate the fur, but still...

Stiffer stool can be achieved by sticking to a well balanced Super Premium Dry Dog Food specifically for their age and breed. My dogs do very well with Dick Van Patten's Natural Balance Duck and Potato formula because they have allergies to corn, soy, etc..

Do not feed your dog anything that's going to interrupt his diet or mess with his digestive, which causes runny stool. Don't give out too many dog treats, limit them so he can be encouraged to eat his dry dog food. Give verbal praises over dog biscuits whenever possible.

Please, no table scraps or food! Chicken bones or beef bones are BAD as they can choke on pieces that are sharp or break their teeth.

No people food what so ever! and just make sure that you are just giving good dog food. It doesn't have to be really expensive, it just has to work for your dog. Do not try changing food without mixing first with the old food, a week half and half is a good try. If that is more wet bowels, then , wait 2 weeks. You must change food slowly, so that their body can adjust.
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If after you have found a food that is good for your dog, you can start some people food. Green beans, raw carrots, and meat that has not been cooked with onions, onions are bad for dogs. Cooked food, is rice, potatoes, carrots, I am sure there is more, can't think right now. Eggs, and even bread, if your dog is low on food, and needs something.
There are alot of sites that you could check out, and they will tell you what your dog will love, and what your dog will not want, but these are just plain stuff that will get you by. Good luck with hardening his stool, I give my dogs a raw egg with their morning kibble every 3 days. That seems to help their coat.

I would either switch to a better dog food, or do some research on a raw diet