Cat resting in the grass.

Gastrointestinal Response to Disease and Treatment

Considering what they have to go through each day, the stomach and intestines make up a remarkable organ system. In the performance of their daily nutritional functions, they must be on constant guard to protect themselves from autodigestion by digestive acids and enzymes produced and must constantly battle foreign organisms and agents that are inadvertently taken in by mouth.

When the stomach and/or intestines become acutely diseased, three major factors come into play that can quickly turn a sometimes seemingly harmless situation into a life-threatening predicament; these include pain, secondary bacterial invasion, and dehydration.


Any inflammation and/or excessive smooth-muscle contractions occurring within the gastrointestinal system can be quite discomforting and painful. In fact, in severe cases of viral enteritis, intestinal obstructions, and intussusceptions, this pain can be so great that the patient goes into life-threatening shock.

As a result, the sooner therapeutic measures are undertaken to correct the problem and stifle the pain associated with it, the less chance of complications occurring.

Secondary Bacterial Invasion

The second factor to contend with is secondary bacterial invasion. Normally, the intestines are inhabited by billions of bacteria that peacefully reside there without causing any problems whatsoever.

In fact, the very presence of these non-disease-causing bacteria actually helps prevent the growth of pathogenic, or disease-causing, bacteria within the intestinal setting. However, if disease strikes the small or large intestine, these “friendly” bacteria can be wiped out, allowing pathogenic ones to proliferate and cause disease themselves.

If the inflammation persists, or if an intestinal perforation occurs, these and any other bacteria within the intestines can leak out of the gut and even gain entrance into the bloodstream, causing a life-threatening systemic infection and shock.

For these reasons, it is obvious that antibiotics become very important in the treatment of moderate to severe cases of gastroenteritis, even if the original cause is nonbacterial in origin.


The final threatening factor that arises when acute gastroenteritis strikes a pet is dehydration. Pets suffering from vomiting and/or diarrhea can quickly become dehydrated as a result of water loss through the bowels.

Since inflamed bowels cannot regulate water absorption as they do when they are healthy, any fluid intake that indeed occurs will usually pass right out of the body via vomiting and/or diarrhea without being absorbed.

In fact, the disruption of normal motility and distension occurring within the affected bowel can actually attract and draw water right out of the body and into the intestinal lumen.

As a result, pets that have become dehydrated or are on the verge of dehydration due to gastroenteritis require intravenous fluids to correct the dehydration occurring within the body’s cells, at least until the gut has healed sufficiently to resume these functions once again.


Once the gastrointestinal system is on the mend, and all vomiting has been brought under control, a good level of nutrition is required to counteract any malnutrition induced by the disease.

Bland diets that are easily digested are prescribed until complete healing of the stomach and/or intestinal linings has taken place.

Offering a convalescent pet some type of electrolyte replacement drinks during these first few days can also promote rapid recovery as well. Feeding plain yogurt is also helpful toward repopulating the gastrointestinal tract with nonpathogenic bacteria.