Many things can give your dog an upset tummy. But many of these things, like a sudden change in diet, a foray into the garbage can or stress from a recent boarding stay, can lead to unhappy intestines, too. Luckily, most cases of diarrhea will resolve on their own, or by feeding a bland diet and/or probiotics for a few days. But occasionally, the problem can persist, and may need veterinary help.
A trip inside the intestines
As food leaves the stomach and enters the small intestine, it continues to be broken down while nutrients are absorbed into the body with the help of a diverse array of bacteria in the intestine.
This complex ecosystem of bacteria is established shortly after birth and is important for good digestive health in several ways. In healthy animals, it helps prevent disease-causing bacteria from becoming established in the intestinal tract. It synthesizes vitamins and provides energy to the cells lining the intestines, and it plays a crucial role in the development of the immune system.
While multiple factors can lead to diarrhea, such as intestinal parasites and food allergies, anything that disrupts the natural balance of bacteria in the digestive tract can result in acute (short-term) or chronic (long-term) diarrhea.
In some cases, bacteria such as those from the Clostridium species can enter the intestinal tract through the mouth, either when your dog ingests contaminated food or eats unspeakable things you can’t pry out of his or her mouth. These bacteria may live in the digestive tract without causing harm. Or they may produce toxins, which can lead to diarrhea. Often, antibiotics are recommended to resolve the problem. This is just one type of the condition known as antibiotic-responsive diarrhea (ARD), also formerly known as “small intestinal bacterial overgrowth.”
In other types of ARD, dogs can experience diarrhea for several weeks, often intermittently. The condition tends to happen in younger, large-breed dogs, especially German shepherd dogs, shar-peis and boxers.
The signs can vary, depending on if the small or large intestines are involved. With the small intestine, a dog may lose its appetite, vomit, and possibly lose weight. There is often a large volume of watery diarrhea.
If the large intestine is involved, the dog may have a normal appetite and energy level but have increased urgency and frequency of defecation. You may also notice your pet straining to “go” or having mucus and/or blood in the stool.
Diagnosis and treatment
If diarrhea continues for more than a few days, a medical workup is warranted. Your veterinarian may recommend a fecal analysis to check for parasites and other problems. Additional testing, including blood work, x-rays and other diagnostics may be suggested to rule out other possible causes including food allergies, exocrine pancreatic insufficiency (a deficiency in digestive enzymes) or inflammatory bowel disease.
Antibiotic-responsive diarrhea can be difficult to diagnose because the bacteria that may cause the problem are often normal inhabitants of the digestive tract. Sometimes, no obvious cause is found, but the diarrhea resolves when the dog is given antibiotics. In many dogs, the diarrhea may return once antibiotics are stopped. In this case, additional diagnostics or treatment options may be explored.
If your dog has chronic or intermittent diarrhea, your veterinarian can help get to the bottom of the problem.