I recently ran into one of my favorite professors from veterinary school at a conference. She used to tell us that in small animal practice “common things are common”. Well folks, guess what: diarrhea is about as common as it gets when talking about canines. Nothing gets a dog into the vet’s office faster than a carpet-destroying episode of diarrhea.
Lots of people ask us here on PetCoach: how can I treat my dog’s diarrhea? It’s frustrating for owners to hear, but while dogs get diarrhea all the time, it has many different causes, and successful treatment of diarrhea hinges on figuring out the underlying cause. Read on to find out the most common causes of diarrhea, and some strategies for dealing with it.
Food
This is a big category into which I’ll lump 3 things: sudden change in diet, food allergies, and food sensitivities. Let’s break each one down.
A sudden change in your dog’s diet can throw his digestive system for a loop. This can happen when the store is out of his typical brand, or when you talk to your best friend and she tells you about how wonderful her dog’s new food is, and you decide to give it a try. Regardless of the reason, abruptly switching foods on your dog can cause diarrhea. Some dogs will do fine with a sudden change, but many don’t, and for this reason I always advise a gradual switch to a new food when possible, mixing in increasing amounts of the new food over a 7 to 10-day period.
Food allergies are sometimes the cause of chronic, recurrent diarrhea in dogs. Dogs can develop allergies to foods they’ve eaten for many years. That’s why when a dog suddenly develops diarrhea and we can’t find other obvious causes, we’ll often try an 8-week trial of a hypoallergenic diet. Many times dogs with food allergies will also have skin problems, such as itchiness and ear infections.
Food sensitivity is sort of a nebulous category. My dog, Pancake, had recurrent bouts of diarrhea, vomiting, and reduced appetite every 3 months or so until I switched her to a hypoallergenic diet. Does she truly have a food allergy? I don’t really think so, because she doesn’t have any other symptoms of a food allergy. But I do think some foods cause her problems, most likely chicken, so we avoid that, and she does fine.
Parasites
Parasites are easily the most common cause of diarrhea in puppies and young dogs, although dogs can get them at any age. Roundworms, hookworms, whipworms, tapeworms, and giardia can all cause diarrhea. Usually we can detect all of these (except tapeworms) on a simple fecal test.
Some parasites are tougher to get rid of than others, and knowing exactly which parasites (or parasiteS) your dog has is critical to getting rid of them. One medication doesn’t kill all parasites, and often multiple doses of medication are needed to completely clear the infection.
Dietary indiscretion
“Dietary indiscretion” has to be one of my favorite veterinary terms. It’s really just a nice way of saying that dogs can and will eat almost anything they can get into their mouths. It must be a strategy that’s generally worked well for them, as the species has thrived (with a little help from humans), but eating stuff you find on the floor and in the garbage can be very upsetting to the gastrointestinal tract and is a major cause of diarrhea in dogs.
Usually when this happens I’ll advise pet parents to withhold food for 12 hours (a shorter period of time for a small puppy) and if the diarrhea stops, start feeding small quantities of a bland diet. I’ll usually recommend something like boiled white meat chicken and boiled white rice with no seasonings or fats added. I’ll recommend mixing about 25% chicken with 75% rice and feeding in small, frequent amounts for 12 hours. The rice adds some fiber, which helps to resolve the diarrhea, and both foods are easily digested for most dogs. If the diarrhea doesn’t resolve with this regimen, the dog should see a vet to determine if there’s something else going on.
Bacterial and viral infections
Most of the time if a dog has a serious infectious disease that’s causing diarrhea, there will be other signs of disease present as well. That’s why when I talk to pet parents about diarrhea, one of the first questions I ask is, “Is your dog feeling well and acting normally otherwise?”. I do this because uncomplicated diarrhea is just that - uncomplicated. It’s dangerous to ignore other signs, as they may indicate the presence of more serious disease.
Parvo virus, salmonella, and leptosporosis are examples of serious infectious diseases that can cause diarrhea, but usually involve other symptoms as well. If your dog is vomiting, lethargic, refusing food, or having copious amounts of very watery and/or bloody diarrhea, he likely has something serious going on, and needs to see a vet immediately.
Stress
As any vet who has worked in a clinic that also provides boarding services will tell you, the stress of being away from and home and family, no matter how posh the surroundings, can bring on diarrhea in some dogs. Theories as to why this happens are many, but it’s most likely that being boarded causes a lot of dogs to refuse food, which changes the flora, or bacterial population, in the gut, resulting in diarrhea.
Most of these dogs will get better on their own, or with the addition of a high-quality veterinary probiotic supplement added to their food. Occasionally they need a temporary diet change to not only stimulate their appetite but add some fiber as well.
Autoimmune disease
Back to the “common things are common” idiom. When the most common causes of diarrhea have been ruled out, and the dog still has diarrhea, it’s time to look for less common causes. Inflammatory bowel disease is an autoimmune disease that attacks the lining of the intestines, resulting in the inability to absorb nutrients and subsequent diarrhea. While not incredibly common, it does occur with some regularity, and any time a dog has recurrent or persistent diarrhea inflammatory bowel disease should be considered as a possible cause.
Inflammatory bowel disease can only be definitively diagnosed with an intestinal biopsy. Sometimes we presumptively treat for this disease, if the owner can’t afford to obtain biopsies, which require abdominal surgery or endoscopy. Most of the time treatment involves suppressing the immune response with medications, which can be successful at resolving the diarrhea, but typically need to be given for life.
Systemic diseases
Almost any serious disease can cause a dog to have diarrhea. This includes kidney disease, liver disease, pancreatitis (inflammation of the pancreas), and metabolic diseases like diabetes.
If your dog’s diarrhea isn’t resolving with standard therapies and routine testing isn’t turning up a cause, he should have blood work in order to determine if any serious systemic diseases are present that could be causing the diarrhea. Again, like serious infectious diseases, typically other signs are present as well.