Gastrointestinal foreign body

What it is

Dogs frequently swallow indigestible objects: bones, toys, balls, stones, corn cobs, fruit stones, socks and other fabrics, and string or rope. Small objects pass in the faeces; larger ones stop where the tract narrows. Mechanical obstruction causes fluid and gas to accumulate proximally, with vomiting, dehydration, electrolyte and acid–base disorders. Pressure on the wall causes ischaemia, necrosis and perforation, leading to septic peritonitis. Linear foreign bodies (string, fabric) anchor at one point — often the pylorus or the base of the tongue — while peristalsis gathers the intestine along them, so that the bowel bunches up (plication) and the object cuts through the mesenteric border.

Who it affects

Dogs of any age, but most often young dogs and breeds prone to chewing and swallowing objects, such as retrievers. Dogs that scavenge or eat bones are at risk of oesophageal foreign bodies.

Anatomy involved

• Oesophagus: objects (often bones) lodge at the thoracic inlet, over the base of the heart or just cranial to the cardia, where the oesophagus cannot dilate as much.
• Stomach: many objects stay there for a long time with intermittent vomiting; the pylorus is a frequent point of obstruction and anchoring.
• Small intestine: the most common site of obstruction, usually the jejunum; linear bodies plicate the duodenum and jejunum.

Clinical signs

Vomiting (acute and repeated with complete proximal obstruction, intermittent with partial or gastric bodies), anorexia, lethargy, abdominal pain and dehydration; sometimes diarrhoea. Oesophageal foreign bodies cause ptyalism, gagging, regurgitation and repeated swallowing. Fever, collapse and severe pain suggest perforation and peritonitis. Linear bodies may be seen under the tongue.

Diagnosis

• History of chewing or a missing object.
• Abdominal palpation: occasionally the object or a plicated intestine can be felt.
• Radiographs: radiopaque objects; in obstruction, segmental gas-distended small intestinal loops (with a clear difference in diameter between dilated and normal loops); in linear bodies, bunched loops with small, comma-shaped gas bubbles. Free abdominal gas indicates perforation.
• Ultrasound: identifies radiolucent objects, plication, wall thickness and peritoneal fluid.
• Contrast studies or endoscopy in selected cases.

Treatment

After fluid and electrolyte stabilisation: endoscopic retrieval for oesophageal and many gastric foreign bodies. Objects that cannot be removed endoscopically are removed surgically by gastrotomy or enterotomy; non-viable intestine is resected with enterectomy and anastomosis. Linear bodies require release of the anchor and often several enterotomies. Peritonitis is managed with lavage, drainage and antibiotics. Inducing vomiting is not advised for sharp or large objects. The prognosis is good when the condition is treated before perforation.

In the cat

In the cat linear foreign bodies predominate: sewing thread (sometimes with the needle still attached), wool, ribbons, hair ties, tinsel and string. The thread is often anchored under the tongue, wrapped around its base, or at the pylorus, while the rest moves along the intestine and plicates it. This is why the base of the tongue must always be examined in a vomiting cat, lifting it carefully or under sedation. Hairballs (trichobezoars) can also cause obstruction, and young cats swallow small toys.

Signs can be subtler than in the dog: anorexia, lethargy, drooling, repeated swallowing and intermittent vomiting. On radiographs linear bodies show bunched intestinal loops with small gas bubbles; ultrasound is very useful. Thread protruding from the mouth or anus must never be pulled, because it can cut through the intestine; in stable cats with a recent thread anchored under the tongue and no intestinal plication it can be cut there and the cat monitored closely, but if it does not pass or signs of obstruction appear, surgery is performed without delay. The prognosis is good when treated before perforation.

Key studies in the cat

• Felts et al. (1984), review of 64 cats with thread or sewing needles as gastrointestinal foreign bodies. Most were under 4 years old. Oral examination combined with abdominal palpation allowed the diagnosis in about 75% of cases, and survey radiographs contributed in 86% of the cats in which they were taken. Surgery was needed in 96.9%; 83.9% of operated cats did well, but only about half of those with intestinal lacerations recovered.
• Basher and Fowler (1987), 24 cats with linear foreign bodies. Nine passed the thread with conservative management within 1–3 days; 10 first managed conservatively needed surgery when signs worsened or the thread did not pass, and 5 were operated on from the start. Cats managed successfully without surgery had been ill for less time and had less abdominal pain and palpable plication. None died. A small, old series.
• Hayes (2009), retrospective study of 208 dogs and cats in first-opinion practice. In cats, survival was 100% with discrete foreign bodies but 63% with linear ones. A longer duration of signs, a linear foreign body and multiple intestinal procedures were associated with higher mortality.
• Gollnick et al. (2023), 56 cats operated on at a university hospital, 38 with discrete and 18 with linear foreign bodies. All survived and none developed septic peritonitis; linear foreign bodies needed longer surgery and had more surgical-site infections.
• Miller et al. (2024), 169 cats operated on for small-intestinal foreign body obstruction. Survival to discharge and complications did not differ between linear and discrete foreign bodies, intestinal dehiscence occurred in only 2 cats, and a red rubber catheter technique removed linear foreign bodies in 20 of 24 attempts.