Scours is foal Diarrhea. And, generally it is normal for any foal at 7-10 days of age (not all foals get it, but you never know. The older the nurse mare foal the better chances you have in not seeing this). People use to contribute this digestive upset in the foals to the mares heat cycle (they go back in heat 7-10 days after foaling) and the hormones associated with that. But, it has been proven to happen in both foals with mom's and orphan foals. They now contribute it to foals being born with sterile intestinal tract (lacking normal bacteria that you find in the foals gut and yours).  It helps if you dose your foal with a pro bios supplement early in life. And for nurse mare foals ad one tablespoon of vanilla or plain yogurt to each gallon of milk re-placer. Foals with mom's of foals with other horses around ingest this normal bacteria in another way. They will eat the feces (poop) of the mare/horse to ingest this bacteria. So, if you notice your foal(s) doing this it is normal. I would not recommend bringing in feces for your orphaned foal(s) to eat from strange horses. But if your foal is around your other horses and does this do not be alarmed. But, as with anything else you should contact your vet. Scours is usually caused by over eating, over feeding, or poor digestion. Remember that a foal will always seem to be hungry, but milk replacer will cause scours if the foal is overfed. Diarrhea can be a serious complication in a foal this young. A temperature should be taken and monitored. The diarrhea could be caused by a bacteria and this should be ruled out by a vet. Usually you are able to successfully stop it with a combination of VBG Diarrhea Control Gel (available from Lambriar Vet Supply Online), Diar-sanyl, Pepto Bismol (Generic fine) and activated charcoal. Working with your vet is very important to keep your foal thriving and healthy! Good Luck!