Intestinal Obstruction and Gastrointestinal Foreign Bodies in Dogs
Any problem that interferes with the passage of intestinal contents through the GI tract results in a blocked bowel. The most common cause is a gastrointestinal foreign body. The second most common cause is intussusception-a situation in which the bowel telescopes in upon itself, like a sock pulled inside out. Most cases of intussusception occur at the cecum, where the small bowel joins the colon. As the small bowel inverts into the cecum and colon, the lead point travels a considerable distance, dragging the small intestine after it. Intussusceptions generally occur in puppies and young dogs.
Other causes of intestinal obstruction are tumors and strictures, adhesions following abdominal surgery, and navel and groin hernias that trap loops of bowel in the hernia sac. In young puppies, heavy infestations of roundworms may obstruct the bowel.
An intestinal obstruction can be partial or complete. Partial obstructions cause intermittent vomiting and/or diarrhea, which tend to occur over several weeks. Complete obstructions produce sudden abdominal pain and vomiting that continues without relief. When the blockage is in the upper small bowel, the vomiting may be projectile. Blockages in the lower GI tract cause abdominal distension and the vomiting of brown, fecal-smelling material. Dogs with complete obstruction pass no stool or gas.
Intestinal strangulation occurs when the obstruction interferes with the blood supply to the bowel. Within hours the bowel becomes gangrenous. The dog's condition deteriorates rapidly (see Peritonitis).
The diagnosis of intestinal obstruction is made by abdominal X-rays or ultrasound showing distended, gas-filled loops of bowel.
Treatment: Obstructions require immediate veterinary attention. Surgical exploration and relief of the blockage is necessary. Gangrenous bowel is resected back to viable bowel, and intestinal continuity is restored with end-to-end suturing of the bowel.
Gastrointestinal Foreign Bodies
Dogs have been known to swallow bones, toys, sticks, stones, pins, needles, wood splinters, cloth, rubber balls, rawhide, leather, string, peach pits, and other objects. With string, one end often knots up while the other gets caught in food. Tension on the string then causes it to cut through the wall of the bowel. Swallowing pennies will not usually cause an obstruction, but can lead to zinc toxicity as the metal leaches out of the coins. Batteries can also cause toxicity when swallowed.
The esophagus of the dog is larger than the outlet of his stomach. Thus, dogs may swallow objects that are too large to pass out of the stomach. Gastric foreign bodies are therefore associated with chronic gastritis and episodes of gastric outflow obstruction.
If an object makes it into the small intestine, it may pass through the entire GI tract without causing problems. Those that do cause an obstruction usually do so at the ileocecal valve or in the colon and rectum. Foreign bodies in the rectum cause anorectal obstructions. Sharp objects such as pins, splinters, and bone chips can lodge anywhere in the GI tract and obstruct or perforate the bowel, causing intestinal obstruction or peritonitis.
Unless it also causes indigestion, a swallowed foreign body will go unnoticed until it produces symptoms. Many foreign bodies can be seen on X-rays of the abdomen if they are radio-opaque. A contrast study may be needed to identify foreign bodies that are not visible on X-rays.
Treatment: Foreign bodies that produce symptoms should be removed. This usually involves abdominal surgery. Gastric foreign bodies can sometimes be removed through an endoscope.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.
Copyright © 2007 by Howell Book House. All rights reserved.