Diarrhea can be due to stress, a quick change in diet, eating unusual rich foods, parasites, inflammatory bowel disease or even a food allergy. It can also be related to metabolic organ disease (such kidney or liver disease) due to organ wastes irritating the gut or a mass in the intestinal tract.
In your pups's case because multiple dogs are affected and they seem to feel well otherwise either something contagious (like a parasite or a bacterial infection) or them getting into and eating something that upset their gastrointestinal tract may have started all of this.
If they aren't bouncing back with my suggestions they should be checked by your regular veterinarian.
Well worth checking at least a couple fresh stool samples too as parasites are a common cause of loose stools in dogs and parasite eggs/cysts are shed intermittently. They may be picked up on the second sample or third test even if the first is negative.
If they are not vomiting and are still wiling to eat we can try some things at home.
I don't normally recommend using Imodium or Lomotil in dogs as it works by slowing the gastrointestinal tract down so that water in the stool can be reabsorbed. It is a narcotic and can lead to sedation and in some dogs can stop normal gut movements entirely. If the diarrhea is related to a bacterial toxin the Imodium allows more toxin to be absorbed.
If their appetites are off and if their stomachs are gurgling they may have some stomach upset and reflux that can go along with loose stools. To try and settle their stomachs today you can give either:
1) Pepcid-ac (famotidine) at a dose of one half of a 10mg tablet per 10 to 20 pounds of body weight every 12 hours.
2) Prilosec (omeprazole) at a dose of one quarter of a 20mg tablet per 10 to 20 pounds of body weight every 24 hours.
These will reduce stomach acid and should help if this is related to simple nausea and gastrointestinal irritation from eating a large amount of rich food. They can be given for several days if need be. If there isn't any stomach gurgling and their appetites are good you can skip this step.
I would not feed any food for 24 hours. This should help stop gut spasms and restore normal gut motility. Small amounts of water or ice cubes given frequently are fine as they need fluids after all that they have lost with diarrhea. You can give pedialyte to replace electrolytes too but Gatorade is much too high in sugar which can make intestinal irritation worse.
Today even with the fast you can start Kao-pectate at 1/2ml per pound of body weight or 1/2 tablespoon per 15 pounds of body weight every 8-12 hours. This will coat an irritated gastrointestinal tract as well as absorbing bacterial toxins. You can use it for several days until stools look normal. You can find kao-pectate at the drug store.
If any pup has a tense painful abdomen, continues to have diarrhea with no improvement after being on kao pectate for 24 to 48 hours, becomes very lethargic, begins vomiting or runs a fever greater than 103.5F then they really must be seen by a veterinarian as soon as possible. Make sure to take a fresh stool sample with you when you go.
After the food fast start a bland diet of 1/3 boiled, lean hamburger (or boiled, white, skinless chicken), all fats and juices drained off the meat, mixed with 2/3 boiled, plain white rice. Feed several small meals a day. You might wish to add 1-2 tablespoons of canned pumpkin (not pie filling, just pumpkin) to each meal if you are seeing mucous in their stool as fiber helps soothe an irritated colon.
You can also add probiotics to the bland diet mix to replace the good bacteria lost with diarrhea. Good brand name products include Fortiflora, Proviable, or Benebac. They can be found online or at pet stores.
Once they feel better (no diarrhea for 48 hours) start mixing in their regular dog food very slowly, less bland more regular with each day. It should take a week or so to convert them back.
If any dog begins vomiting and feeling poorly though it would be best that he/she see a veterinarian now as anything you give orally will just come back up worsening the pup's dehydration.
Please let me know if you have any further questions.