There is normally a large population of bacteria that reside in both the large and small intestines of dogs- especially the large intestine. As long as the various types of bacteria remain in the proper balance, and in the proper numbers, digestion occurs as it should. Small intestinal bacterial overgrowth (SIBO) occurs when ‘bad' bacteria grow and multiply more than they should in the small intestine. This occurs when, for various reasons, there is undigested material sitting around for too long in the small intestine, allowing the bacteria to grow and thrive for an extended period. SIBO is most common in dogs who suffer from previous medical conditions such as neurologic problems, gastrointestinal obstruction, parasites, pancreatitis, and other issues. The following symptoms and treatments are common for dogs who suffer from SIBO.


Chronic diarrhea is one of the most common signs of SIBO in dogs. For dogs without pre-existing medical conditions, chronic, intermittent diarrhea may be a sign of idiopathic SIBO ("Idiopathic" simply means that that the original underlying cause is not fully understood). Small-bowel diarrhea is the most common type of diarrhea that will accompany it, and it is characterized by limited straining and large volumes.

what is SIBO dogs



Another telltale sign of SIBO is increased flatulence. While the large intestine is home to many bacteria, normally the small intestine contains much smaller populations. An overabundance of bacteria in the small intestine and the resultant poor digestion causes the flatulence. Large-breed dogs, especially German shepherds, are overrepresented in idiopathic SIBO, or idiopathic antibiotic-responsive diarrhea (ARD).



Weight loss

If your dog is suffering from chronic diarrhea and is losing weight despite a normal or increased appetite, it is possible that he has SIBO. SIBO is a type of malabsorption syndrome. This means that a dog with SIBO cannot properly absorb the nutrients from his food due to the interference with the digestive process. The result is weight loss, which can be especially dangerous for small, young dogs.

weight loss SIBO


Stunted growth

Young dogs that develop SIBO are in danger of not developing and growing properly. The small intestine is where nutrients from their food begin to be extracted and absorbed into the bloodstream. The nutrients are then carried to all parts of the body for proper functioning, development, and growth. Puppyhood is a critical age in which all those nutrients are required for development and growth. When puppies are cut off from these nutrients, their growth may be stunted temporarily or permanently.

stunted growth dogs


Irrational hunger

A dog with SIBO may appear ravenous even if she is eating the proper amount for her age. Since her body is not absorbing nutrients as it should, it sends a signal to her brain, instructing her to eat more food for extra nutrients.

hunger SIBO



Pica is a condition in which a person or an animal—a dog, in this case—develops a seemingly irrational appetite for non-nutritive or indigestible items. When this behavior persists for a month or longer, it is characterized as pica. Dogs with SIBO may begin to eat their stool or other indigestible items which can cause damage to the intestines. One theory for why a person or animal may develop pica is due to mineral deficiency. A dog with SIBO may not be absorbing all the nutrients he needs to thrive, so he develops a hankering for other objects which may contain minerals he lacks.

pica SIBO



Idiopathic SIBO is usually treated with oral antibiotics. In fact, it is often called antibiotic-responsive SIBO because it responds well to antibiotics. Secondary SIBO may be approached differently because a different medical condition causes the SIBO, and therefore may not be easily treated with antibiotics. In such cases, the underlying cause will need to be addressed to treat the condition properly.

antibiotics SIBO



A dog receiving regular doses of antibiotics may also receive probiotics to replace the good bacteria being flushed out of her system. Digestion and nutrient absorption rely on good bacteria to break down the food. The digestive system requires a delicate balance of bacteria to function properly.



Dietary changes

Your veterinarian may suggest adjusting your dog's diet to accommodate his sensitive gut. Dairy products are not recommended for dogs with SIBO because intestinal damage affects the lactase available in the gut that is needed to break down dairy. Your dog may also require a low-fiber diet for a while, to limit the intake of "fuel" needed by the bad bacteria to grow in the small intestine.

SIBO dietary



If your dog has SIBO, she is probably lacking in nutrients. Nutritional supplements can help get your dog back on track so that she can continue to develop and grow. Ask your veterinarian which supplements she recommends to fill in your dog's nutritional gaps.


If you notice a change in dietary habits or other signs, take your dog to the vet. SIBO can be difficult to diagnose and is often a process of ruling out other causes of the symptoms. In this ‘ruling out' process, description and history of the symptoms are very important. Remember, you know your pet better than anyone.


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