The bottom line part 2... must come out

Diaorrhea in Dogs: Causes and Treatment
 
Diaorrhea is the passage of loose, unformed stools. In most cases there is a large volume of stool and an increased number of bowel movements. The two most common causes of diaorrhea in dogs are dietary indiscretion and intestinal parasites. Many canine infectious diseases are also associated with acute diaorrhea.

Food takes about eight hours to pass through the small intestines. During that time, the bulk of the food and 80 percent of the water is absorbed. The colon concentrates the remainder. At the end, a well-formed stool is evacuated. A normal stool contains no mucus, blood, or undigested food.

With rapid transit through the bowel, food arrives at the rectum in a liquid state, resulting in a loose, unformed bowel movement. This type of rapid transit accounts for the majority of temporary diaorrhea in dogs.

Dietary indiscretion is a common cause of rapid transit. Dogs are natural scavengers and tend to eat many indigestible substances, including garbage and decayed food, dead animals, grass, wild and ornamental plants, and pieces of plastic, wood, paper, and other foreign materials. Many of these are irritating to the stomach as well as to the bowel, and are partially eliminated through vomiting.

Food intolerance can also cause rapid transit. Foods that some dogs seem unable to tolerate can include beef, pork, chicken, horsemeat, fish, eggs, spices, corn, wheat, soy, gravies, salts, spices, fats, and some commercial dog foods. Note that food intolerance is not the same as food allergy, which causes dermatitis and possibly vomiting, but rarely causes diaorrhea.

Intestinal parasites are a common cause of acute and chronic diaorrhea in puppies and adults. The greatest problems are caused by roundworms, hookworms, whipworms, threadworms, and giardia.

Diaorrhea is a common side effect of many drugs and medications, particularly the NSAIDs,which include aspirin. Some heart medications, some dewormers, and most antibiotics also can cause diaorrhea.

Dogs can experience diaorrhea when they’re excited or upset-for example, when they’re going to the veterinary hospital or a dog show. In fact, any sudden change in a dog’s diet or living circumstances may cause emotional diaorrhea.
 
Home Treatment of Diaorrhea 
The most important step in treating acute diaorrhea is to rest the GI tract by withholding all food for 24 hours. The dog should be encouraged to drink as much water as he wants. With persistent diaorrhea, consider giving a supplemental electrolyte solution such as Pedialyte, available over the counter in pharmacies and grocery stores. Dilute it by one-half with water and add it to the dog’s drinking bowl. Custom canine electrolyte solutions and sport drinks are also available, such as K9 Thirst Quencher. These are flavored to encourage the dog to drink. If the dog won’t drink the electrolyte solution, offer only water. A low-salt bouillon cube dissolved in the water can help encourage him to drink.

Acute diaorrhea usually responds within 24 hours to intestinal rest. Start the dog out on an easily digestible diet that’s low in fat. Examples are boiled chicken with the skin removed. Cooked white rice, cottage cheese, cooked plain pasta and soft-boiled eggs are other easily digestible foods. Feed three or four very small meals a day for the first two days. Then slowly switch the diet back to the dog’s regular food.

Obtain immediate veterinary care if:

• The diaorrhea is consistent and continues for more than 48 hours
• The stool contains blood or is black and tarry
• The diaorrhea is accompanied by vomiting
• The dog appears weak or depressed or has a fever

Chronic Diaorrhea
The first step is to find and treat the underlying cause. Diaorrhea resulting from a change in diet can be corrected by switching back to the old diet and then making step-by-step changes to pinpoint the cause. When lactase deficiency is suspected, eliminate milk and dairy products from the diet, particularly as they are not required for adult dogs.
 
Diaorrhea caused by overeating (characterized by large, bulky, unformed stools) can be controlled by tailoring the diet more accurately to the caloric needs of the dog and feeding his daily ration in three equal meals.
 
Chronic, intermittent diaorrhea that persists for more than three weeks requires veterinary attention.

With thanks to webMD

The bottom line part 1 - what goes in

It's not a pleasant subject but sooner or later your dog is going to experience an upset stomach and as a result, diaorrhea. More often than not an upset stomach and the odd bout of diarrhea is nothing to worry about. Dogs are scavengers and can and will eat some fairly disgusting things when given half the chance. Most upsets rectify themselves within 48 hours or so, during which time it is best to either starve your dog or provide a bland and binding alternative to their normal food, such as boiled rice and chicken. Charcoal biscuits are also known to help settle an upset stomach. 

Sometimes however an upset stomach can indicate a more serious problem. If your dog has diaorrhea for more than a few days it is worth making a visit to the vet. In such cases you will normally be advised to feed a bland and regimented diet with minimal treats or chews.

Much like humans, too much of anything can cause a problem. Some commercial dog foods, particularly wet foods, can prove too rich for some dogs. If you find that your dog is not doing well on a wet food then it is worth trying a different brand or considering changing to a dry food. Many breeders have a favourite brand of food and many vet surgeries receive commission from selling the more 'high end' brands such as Hills, Iams and Science Plan. Just because you have a brand recommended to you does not mean that it is the only suitable option. Let your dog be your guide, if something doesn't suit him you will soon know and with so many types of food out there there is no reason not to feed your dog a diet that both you and your dog are happy with.

Many people feed their dogs rigid amounts at set meal times. This may not necessarily be the best option for you and your dog. Different breeds of dog have different needs both in terms of type and quantity of food. Puppies in particular need to eat a vitamin rich food several times a day. While some dogs do gorge themselves at every opportunity - most notably Labradors - there are plenty more dogs who benefit from free feeding. With this method you provide your dog with a bowl of food and allow them to work their way through it as and when they wish. Interestingly puppies who are free fed tend not to develop the habit of bolting their food or becoming food obsessed - both of which can have severe health implications. 

All too often we see dogs who are fed a rigid amount and who as a result practically inhale their food. If as puppies they had been able to eat as much as they needed when they needed it is likely that they would not feel that any food on offer must be eaten as quickly as possible before it is gone.