An intussusception is a telescoping of one part of the intestinal tract into an adjoining segment of intestinal tract. Intussusceptions can occur anywhere throughout the gastrointestinal tract but are most common in the small intestines. Partial or intermittent intussusceptions are often associated with chronic, or waxing and waning signs. A complete intussusception with a total blockage of the intestine may cause acute onset of severe clinical signs, with even shock and death. In general, when the blockage is high in the gastrointestinal tract, the signs are more severe and life threatening.

Many problems can cause intussusceptions, and many other diseases/disorders have the same symptoms. These include:

Viral enteritis, specifically parvovirus, which is a contagious virus that affects dogs

Bacterial enteritis, an inflammation/infection of the intestinal tract with agents such as Salmonella, Clostridia

Intestinal parasites such as roundworms, hookworms and whipworms

Ingestion of foreign bodies

Hemorrhagic gastroenteritis (HGE), a disease syndrome seen in dogs characterized by the acute (sudden) onset of bloody diarrhea

Mesenteric volvulus or twisting of the tissue that suspends the intestines in the abdomen

Gastrointestinal masses (tumors)

Hypoadrenocorticism (Addison's disease), an endocrine disorder arising from adrenal hormonal deficiency

Pancreatitis or an inflammation of the pancreas