Diarrhea in Dogs & Cats

What is diarrhea?
Diarrhea is soft-to-runny stool.

Why is diarrhea harmful?
Diarrhea is harmful because it causes dehydration and can cause infection throughout a pet’s body. Diarrhea is also harmful because often the organisms that are making the pet sick can infect humans, spreading the illness to the pet’s family.

How does diarrhea cause dehydration?
With diarrhea, water that is normally reabsorbed by the intestines is lost in runny stool. The pet becomes dehydrated and doesn’t have enough fluid in its body to clear out toxins and rid itself of the infection. As diarrhea progresses, the amount of fluid in the blood declines and the blood pressure falls. As the pet’s body senses changes in the blood and blood pressure, its heart beats faster to maintain circulation. The pet’s body attempts to bring in fluid from the cells to maintain blood flow, and the cells and spaces between cells become dry. We can see how dry and dehydrated the pet is by pinching its skin. When dehydrated, skin remains tented up, failing to fall back into place quickly as it does when normally hydrated.

Measuring dehydration caused by diarrhea
How can we tell if a pet is dehydrated? Check the mouth, skin, and eyes. First, put your finger in the mouth and feel the gums. In dehydrated pets, gums are dry or tacky rather than moist. Then, check the skin by pinching skin into a fold along the back. Watch how quickly the skin springs back against the body. In well hydrated pets, the skin springs back instantly. In dehydrated pets, a “tent” of skin forms; the tent slowly returns to its original position. When dehydration is severe, eyes appear sunken and dull.

How does diarrhea cause widespread, or systemic, infection?
Diarrhea can cause widespread infection if the infection erodes through the gut wall and into capillaries. Capillaries are located just outside the gut; as the gut wall erodes, blood flows into the intestine, and infectious organisms flow into the blood. In the gut, blood combines with feces and produces a dark, foul-smelling stool. In the blood, infectious organisms are transported throughout the body. Pets with boss of the gut-blood barrier can develop fevers, headaches, and widespread skin and organ infection. For example, the kidneys can become infected and lose the ability to clear the body of wastes.

How to treat diarrhea
We treat diarrhea with

1. Probiotics
2. Prescription medications

1. Probiotics
Probiotics are living organisms that nourish gut cells and keep them healthy. The normal gut has hundreds of different types of bacteria & yeast organisms that surround and nourish the cells. For this reason, probiotics that supplement only a single type of organism are not as beneficial as probiotics that provide a variety of organisms. Fast Balance GI is an example of an excellent probiotic because it has a variety of probiotic organisms, and it does not contain corn (maltodextran) or animal byproducts that aggravate allergic pets.

2. Prescription Medications
Some pets with diarrhea need prescription medications to rid the gut of invading germs. Commonly used medications include antibiotics that kill giardia (Metronidazole and Fenbendazole), and coccidian (Sulfa). In addition, clay-based products (Diarsanyl) are prescribed to absorb toxins in the gut. In order to prescribe the best medication, your vet needs a fresh stool sample that can be sent to the lab. The lab identifies bacteria, yeast, microorganisms, and worms present in the sample.