Intestinal Foreign Bodies in Dogs and Cats

Abstract

Intestinal foreign bodies are some of the most common causes of intestinal obstruction
in dogs and cats. The size of the foreign body determines whether obstruction is partial or
complete. Life-threatening complications caused by fluid and electrolyte imbalances, hypovolemia,
and toxemia may be associated with intestinal foreign bodies. Diagnosis is made on the
basis of clinical signs and results of radiography and ultrasonography and is confirmed by
abdominal exploration. Most foreign bodies can be removed through one or more enterotomies.

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Intestinal Foreign Bodies
in Dogs and Cats
Aristotle University of Thessaloniki
Thessaloniki, Greece
L. G. Papazoglou, DVM, PhD, MRCVS
M. N. Patsikas, DVM, PhD, DECVDI
T. Rallis, DVM, PhD
ABSTRACT: Intestinal foreign bodies are some of the most common causes of intestinal obstruc-
tion in dogs and cats. The size of the foreign body determines whether obstruction is partial or
complete. Life-threatening complications caused by fluid and electrolyte imbalances, hypo-
volemia, and toxemia may be associated with intestinal foreign bodies. Diagnosis is made on the
basis of clinical signs and results of radiography and ultrasonography and is confirmed by
abdominal exploration. Most foreign bodies can be removed through one or more enterotomies.
Dogs and cats may ingest foreign bodies (FBs) that cause intestinal
obstruction, which is one of the most common intestinal disorders
requiring emergency surgical treatment. FBs may lodge in any part of
the intestinal tract; obstruction most often develops in the small intestine when
the luminal diameter becomes smaller.
FB obstruction may be classified1–3 on the basis of:
•Degree of obstruction (complete or partial)
•Location of obstruction along the intestinal tract (proximal or “high”; mid-
dle; distal, or “low”; and colonic)
•Pathophysiologic alterations (simple, or mechanical, versus strangulating)
The degree of obstruction is usually dictated by the size of the FB. Small irreg-
ular or linear FBs can cause partial obstruction (with limited passage of fluid or
gas), whereas complete obstruction may be attributed to large circular FBs. A
high intestinal obstruction involves the duodenum or upper jejunum; a middle
intestinal obstruction, the middle jejunal region; and a low intestinal obstruc-
tion, the distal small intestine. FBs usually induce simple (or mechanical) intes-
tinal obstruction in which no compromise in the intestinal wall blood supply
occurs. A strangulating obstruction, which is usually complete, involves impair-
ment of the blood supply of the involved intestinal segment. However, in clini-
cal situations few obstructions are purely simple because there is almost always
some form of vascular impairment in the affected region of the intestinal wall.3
Knowledge of pathophysiology is essential for correct diagnosis and quick and
systematic treatment of the patient with suspected intestinal obstruction.
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■Ultrasonography is a valuable
tool for diagnosis of intestinal
foreign bodies.
■Proper fluid and electrolyte
administration is essential for
management of patients with
intestinal foreign bodies.
■Asymptomatic cats with linear
foreign bodies may be managed
conservatively.
830 Vol. 25, No. 11 November 2003
Article #2 (1.5 contact hours)
Refereed Peer Review
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KEY FACTS
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and ileal mucosa for reabsorption.2In distal intestinal
obstructions, some fluid moves proximally by reverse
peristalsis and reaches a nondistended intestinal loop,
where normal absorption occurs.2Although the patho-
physiology of these events has yet to be completely
defined, four major mechanisms of hypersecretion and
decreased absorption may exist:
•Hypersecretion mediated by enteric bacterial toxins
secreted by noninvasive pathogenic bacteria that
bind specific enterocyte receptors and stimulate salt
and water production via the messenger cAMP or
cyclic guanosine monophosphate pathways4,5
•Increased concentrations of bile and fatty acids and
products of tissue ischemia at the obstruction site4
•Increased blood flow in the proximal parts of the
intestinal obstruction that may stimulate secretory
activity10
•Release of serotonin (5-hydroxytryptamine) by
enteroendocrine cells that may be stimulated by
increased luminal distention, which activates reflex
pathways that increase chloride ion secretion11
Moreover, chemical mediators of the enteric nervous
system, such as acetylcholine, vasoactive intestinal
polypeptide, and substance P, activate chloride ion–rich
fluid secretion by various mechanisms.5,12,13
The effects of luminal distention are related to the
increasing intraluminal pressure generated proximal to
Ingested air and fluids
Diarrhea
Vomiting Fluid and electrolytes
Gas and fluid distention
Foreign
Body
Edematous intestinal wall
Cause of lymphatic and venous congestion
Secretion
Absorption
Myoelectric activity
Bacterial overgrowth and toxins
Mucosal pressure causes
ischemia/necrosis
Figure 1—Basic pathophysiologic mechanisms of FB-induced intestinal obstruction.
PATHOPHYSIOLOGY
Intestinal obstruction involves a complex interaction
of local and systemic factors1,2,4,5 (Figure 1), which
remain partly obscure. Life-threatening complications
result because of fluid, acid–base, and electrolyte imbal-
ances, hypovolemia, and toxemia.4,6
In complete simple intestinal obstruction, accumula-
tion of gas and fluid contributes to luminal distention
proximal to the obstruction.1,7 Most of the gas is swal-
lowed air (70% nitrogen, 10% to 12% oxygen, and 1%
to 3% hydrogen); carbon dioxide (6% to 9%) formed as
a result of bicarbonate neutralization in the intestinal
lumen; and organic gases (methane [1%] and hydrogen
sulfide [1% to 10%]) derived from bacterial fermenta-
tion.1Gaseous luminal distention gradually increases be-
cause nitrogen is not absorbed by the intestinal mucosa.3
Accumulating fluids come from two sources: an
increased amount of secretion in the upper gastrointesti-
nal tract (saliva and bile, and gastric, pancreatic, and
small intestinal secretions) and retention of ingested flu-
ids.2Solute absorption is reduced because of lymphatic
and venous congestion, increased intraluminal osmolal-
ity, and decreased enterocyte turnover rate.2,8,9 After 24
hours of obstruction, the distended bowel may lose its
ability to absorb fluids, and local hypersecretion is
observed.2Intraluminal fluid volume is increased as the
obstruction becomes prolonged.8In complete proximal
intestinal obstructions, a large quantity of secretions and
ingested fluids cannot establish contact with the jejunal

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fluid lost and its metabolic effects depend on the degree,
location, and duration of the intestinal obstruction. Fluid
and electrolyte losses are caused by vomiting, sequestra-
tion in the intestinal lumen, diarrhea, intestinal wall
edema, and extravasation into the peritoneal cavity.3,4
Clinical signs of partial intestinal obstruction are
associated with maldigestion and malabsorption of
nutrients (stagnant loop syndrome). Diarrhea may be
attributed to combined osmotic effects of unabsorbed
substances in the intestinal lumen and to secretory
activity of enterocytes.6,9 FB-induced colonic obstruc-
tion is usually partly due to distensibility of the colon
and its slightly rhythmic segmentation.3Obstruction
causes large quantities of feces to accumulate in the
colon and water and electrolyte absorption to take
place, often prolonging the course of the disease.6
NONLINEAR FOREIGN BODIES
Dogs, especially young dogs (mean age, 3.5 to 3.7
years),17 may ingest a large variety of nonlinear FBs.4,17,18
Young dogs commonly chew on objects, and the recent
disappearance of an object may raise suspicion of intes-
tinal obstruction. In dogs, the nonlinear FBs most
often encountered include stones, plastics, fabrics,
coins, rubber objects, food wrappings, toys, bottle caps,
fish hooks, sewing needles, marbles, corn cobs, hair-
balls, fruit seeds, tampons, and bones.4,17,18 In cats,
however, ingestion of nonlinear FBs, except trichobe-
zoars, is rare.19 Round smooth FBs, such as balls, may
cause complete intestinal obstruction and pressure
necrosis of the intestinal wall. Sometimes, if they move
down the intestine, these objects can cause intestinal
edema.3Sharp FBs may penetrate the intestinal wall
and cause septic peritonitis and adynamic ileus.
Diagnosis
Clinical Signs and Physical Examination
Findings
The clinical picture and survival associated with intes-
tinal obstruction depend on the degree of obstruction,
location of obstruction, and changes in intestinal blood
flow.6Complete obstructions are usually more acute
than are partial obstructions, proximal obstructions are
more acute than are distal obstructions, and strangulat-
ing obstructions are more severe than are simple
obstructions.6Common clinical signs include anorexia,
dehydration, depression, abdominal pain or discomfort,
and vomiting.17,20 Intestinal obstruction should be
included in the differential diagnosis of a patient with
acute vomiting, chronic diarrhea, acute abdomen, and
weight loss. The differential diagnosis includes acute
gastritis, intussusception, acute pancreatitis, peritonitis,
and parvoviral enteritis in young dogs.
the intestinal obstruction and to the duration of the
obstruction.1Intraluminal pressure proximal to the
obstruction increases gradually because of fluid and gas
accumulation (Figure 1). The arterial circulation is not
affected, but capillary bed congestion may occur and
lead to elevated hydrostatic pressure that produces
intestinal wall edema.3In addition, fluid can be
extravasated through the serosal surface to the peri-
toneal cavity.2Experimental studies with dogs docu-
mented selective mucosal ischemia after simple intes-
tinal obstruction, when intraluminal pressure rose
above 40 mm Hg.14 At a pressure of 44 mm Hg, the
blood supply to the intestinal segment may be severely
compromised so that blood is shunted away from intes-
tinal capillaries and into arteriovenous anastomoses. In
spontaneous intestinal obstruction, full-thickness
necrosis of the intestinal wall may not be seen in the
dilated proximal segment because intraluminal pressure
is apparently below 50 mm Hg.14 Large FBs, because of
the pressure that they apply on the intestinal wall, may
cause venous stasis and edema followed by arterial flow
compromise, ulceration, necrosis, and perforation.1
Also, linear FBs may cause increased peristaltic activity
proximal and distal to the obstruction site and con-
tribute to intestinal wall laceration.1
Intestinal luminal distention causes increased myo-
electric activity proximal to the obstruction and a
simultaneous decrease distally.15 As the duration of
obstruction is prolonged, clusters of intense myoelectric
activity that migrate distally are interrupted by periods
of absent motor activity. These periods of inactivation
may represent a protective mechanism because unin-
hibited hyperperistalsis may result in elevated intralu-
minal pressure that can lead to ischemia and rupture.15
Increased myoelectric activity proximal to an intestinal
obstruction appeared to be cholinergically mediated,
whereas noncholinergic nonadrenergic pathways may
mediate distal inhibition of spike bursts.16
Simple intestinal obstruction may cause an increase
in the intraluminal pathogenic bacterial population as a
result of stasis or loss of the migratory myoelectric com-
plex, which helps move intestinal contents distally and
keeps bacterial numbers low.2,4 Prolonged and severe
luminal distention may impair the enteric mucosal bar-
rier and result in increased permeability and entry of
bacteria and toxins into the systemic circulation, caus-
ing endotoxic shock, or into the peritoneal cavity,
resulting in septic peritonitis.1Prompt decompression
of obstruction is advisable because it allows quick
mucosal regeneration.14
A significant amount of fluids and electrolytes can be
lost in simple obstruction, which results in hypovolemia
and electrolyte and acid–base imbalances.1The volume of

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Vomiting may lead to dehydration and depression. In
these situations, signs of malabsorption and maldiges-
tion are noted. In experimental complete proximal
intestinal obstruction in dogs and cats, vomiting began
within 24 to 72 hours after obstruction.2,8,21 Profuse
vomiting may be seen in complete proximal obstruc-
tions, whereas vomiting is usually intermittent in par-
tial distal obstructions and may be seen 2 to 3 days
after obstruction.2Defecation may be absent17 or
decreased in frequency; bloody stools may occur, with
or without mucus. Diarrhea is common in animals
with partial intestinal obstruction. Distal intestinal
obstruction is characterized by lethargy, anorexia, and
weight loss; animals can drink but not eat.2
Careful abdominal palpation may or may not reveal
the presence of an FB17,18 and intestinal fluid and gas
accumulating proximally. In deep-chested dogs, abdom-
inal palpation is facilitated if the front legs are elevated.
Palpation may elicit abdominal pain,17 and sedation is
required for nervous animals. Abdominal auscultation
may detect noise resulting from peristaltic rushes or
silence in the case of adynamic ileus or peritonitis.4
The major cause of death in animals with proximal
intestinal obstruction may be hypovolemia and acid–
base and severe electrolyte imbalances. With no treat-
ment of these disorders, death usually results in 3 to 4
days.1If the animal survives, toxemia caused by bacter-
ial proliferation in the obstruction site may also cause
death.6In distal intestinal obstruction, however, ani-
mals may live for 3 weeks or longer if water intake is
adequate.2Fluid loss and toxemia related to bacterial
proliferation are causes of death in complete distal
intestinal obstruction. In chronic colonic obstructions,
animals become anorectic and die of starvation.6
Laboratory Findings
Laboratory findings vary according to the nature of
the intestinal obstruction. Packed cell volume and total
protein levels may be elevated, and serum albumin con-
centration may be decreased. Intestinal perforation may
cause leukocytosis with a shift to the left. In early stages
of pyloric obstruction, vomiting of gastric juices that
are rich in potassium, sodium, hydrogen, and chloride
ions may result in hypochloremic, hypokalemic, and
moderately hyponatremic metabolic alkalosis.2Duode-
nal and proximal jejunal obstructions may be associated
with vomiting of intestinal contents containing
hydrochloric acid and pancreatic secretions rich in
bicarbonate, which results in mild metabolic acidosis
and dehydration.2In distal intestinal obstruction, prox-
imal intestinal secretions rich in bicarbonate are
sequestered at the obstruction site. Bicarbonate loss,
dehydration, and starvation contribute to development
of metabolic acidosis.1In cases of chronic intestinal
obstruction, a slight increase in the activity of alanine
aminotransferase, alkaline phosphatase, and lipase, as
well as in blood urea nitrogen and creatinine concentra-
tions, may be noted.
Diagnostic Imaging
Radiopaque intestinal FBs can easily be seen in plain
radiographs (Figure 2). Certain other nonopaque FBs
can be identified on the basis of a typical shape and
contained gas lucencies22 (Figure 3). Diagnosis of radio-
lucent intestinal FBs is based on radiographic signs of
intestinal obstruction. The radiologic diagnosis of FB-
induced intestinal obstruction is usually based on signs
that may include localized intestinal distention related
to gas or fluid accumulation, distended intestinal loops
Figure 3—Lateral abdominal radiograph showing a peach
seed (arrowheads) in the small intestine of a dog.
Figure 2—Lateral abdominal radiograph showing a plastic FB
in the small intestine of a dog.

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be used for the study.26 Barium-impregnated polyethyl-
ene spheres were developed to assist in the diagnosis of
intestinal obstruction in dogs and cats. Radiopaque
spheres may have a high sensitivity for diagnosis of
chronic partial intestinal obstruction. In acute simple
intestinal obstruction, however, spheres are of limited
use because they cannot differentiate functional intes-
tinal obstruction from simple.27
Ultrasonography appears to be a valuable adjunct to
radiography for detection of FBs (Figure 4). Acoustic
patterns vary, depending on the physical properties of
the FB and interaction with the ultrasound beam. FBs
that transmit sound can be accurately detected; strongly
attenuating FBs produce acoustic shadows that, if seen
in association with the intestinal lumen, can be a useful
indicator of an FB.28
Treatment
Conservative
Some small, sharp FBs, such as pins, sewing needles,
and fish hooks, that are found in asymptomatic animals
may be treated conservatively and will pass unevent-
fully, possibly because of the generation of local intes-
tinal dilation (mural withdrawal reflex) in response to
contact between the mucosa and this kind of FB.4FB
transit through the intestinal tract should be monitored
radiographically, and the animal should be evaluated
clinically on a regular basis to ensure uncomplicated FB
passage.3,20 Movement of the FB through the ileocolic
junction is not an indication of complete elimination
because colonic or rectal perforation is still possible.3
Occasionally, a nonlinear FB that causes a large intes-
tinal obstruction may be dislodged endoscopically.
Conservative treatment of hairballs in long-haired cats
Figure 4—Two ultrasonographic appearances of intestinal FBs in dogs.
that lie in layers parallel to each other and are con-
nected with sharp hairpin turns, and unequal gas–fluid
interfaces seen in a standing lateral projection.7,23 Distal
intestinal obstruction may produce greater distention
with more accumulation of fluid or gas compared with
proximal intestinal obstruction.20 The differential diag-
nosis should include other intraluminal, extraluminal,
or intramural causes of intestinal obstruction. Ady-
namic ileus produced by parvoviral enteritis in young
dogs may be considered.23
Diagnosis of intestinal distention may be aided by
use of the ratio of maximum intestinal diameter to the
height of the body of the fifth lumbar vertebra at its
narrowest point. Values higher than 1.6 indicate the
presence of distention; values higher than 2 indicate a
high probability of obstruction.24 No intestinal disten-
tion may be evident in cases of partial obstruction, but
accumulation of indigestible material proximal to the
obstruction may be noted (“graveling” sign).4
In questionable cases, diagnosis requires examination
of the intestinal tract with contrast enhancement. A
radiolucent area surrounded by contrast material out-
lining the FB may be visualized. Prolonged gastric
emptying or small intestine transit time or complete
stasis (depending on the degree of obstruction) charac-
terizes simple intestinal obstruction.25 Dilution of the
barium suspension can be seen in a distended, fluid-
filled, proximal intestinal segment.25 Contrast studies
may be repeated at 6-hour intervals after barium
administration for diagnosis of most proximal small
intestinal obstructions; for repeated studies of most dis-
tal small intestinal obstructions, 24-hour intervals are
needed.20 In cases of suspected intestinal perforation, a
water-soluble contrast agent rather than barium should
AB
Figure 4A—The irregular curvilinear strong echogenicity that
casts a “clear” shadow represents metallic wires obstructing
the intestinal lumen.
Figure 4B—A rubber ball (FB) in the small intestine. The ball
has echogenic borders but is anechoic.

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characterizes the distended intestinal loops. The affected
intestinal segment is exteriorized and isolated from the
other viscera by moistened laparotomy sponges. Intesti-
nal viability may be best assessed after decompression of
the distended loops and removal of the FB.
An enterotomy distal to the FB is performed in the
antimesenteric border, and the FB is removed. Incisions
over the FB or proximal to the obstruction in the dis-
tended intestine may interfere with normal intestinal
healing, possibly because of some degree of vascular
compromise of the intestinal wall, and therefore such
incisions are not recommended.20 The enterotomy is
closed in a single layer with a simple interrupted or
continuous approximating pattern,31 by using 3-0 or 4-
0 synthetic absorbable sutures (polydioxanone, polygly-
conate). Monofilament nonabsorbable sutures such as
polypropylene or skin staples may also be used. Suture
bites are spaced 2 to 3 mm from the incision edges and
3 to 4 mm apart.32 After closure, the enterotomy is
lavaged with warm sterile saline, and omentum is put
around the incision to prevent leakage. Serosal patch
reinforcement is advised for the contused intestinal wall
to prevent postoperative leakage. For enterotomies in
an intestinal loop with a small diameter, a transverse
closure is preferable to a longitudinal one to avoid
stenosis. On rare occasions, FBs such as needles, bones,
and hairballs that are entrapped in the colon wall
require colotomy for removal. Most colonic FBs can be
milked distally to a point where they may be retrieved
by using long forceps inserted through the anus.
In most cases of simple intestinal obstruction, intes-
tinal viability is preserved, and the appearance of dark
distended loops improves as soon as decompression and
FB removal are achieved.2If nonviable tissue is present,
intestinal resection and anastomosis are required. Clini-
cal criteria for intestinal viability assessment may
include wall color, presence of arterial pulsations, or
peristaltic contractions induced by a mechanical stimu-
lation such as a pinch.2However, these criteria do not
give consistently accurate results.26 Fluorescein dye (20
mg/kg injected IV) viewed by a Wood’s lamp may assist
in the appreciation of intestinal wall vascularity.20 If via-
bility is questionable and a significant length of intes-
tine is not involved, intestinal resection and anastomo-
sis would be safer and easier to perform.
Finally, the abdominal cavity is lavaged with warm
sterile saline and the celiotomy incision is closed
routinely.
Postoperative Care and Complications
Maintenance fluid and electrolyte therapy should
continue until the patient starts eating again. Usually,
food and water are started 24 hours after surgery, pro-
may include administration of semisolid petrolatum-
based laxatives for lubrication and easy aboral elimina-
tion of the hairball and introduction of a commercial
diet to facilitate passage of ingested hair (e.g., Hill’s Sci-
ence Diet Hairball Control formula).19
Surgical
Treatment of FB-induced intestinal obstruction is
achieved by exploratory celiotomy. Preoperative stabi-
lization of the patient includes antibiotic prophylaxis
and management of fluid, acid–base, and electrolyte
imbalances. Prophylactic antibiotics are indicated in
animals with intestinal obstruction for two reasons: (1)
surgical techniques involving entrance to the intestinal
lumen are considered clean-contaminated, and (2) the
risk of contamination is high because of bacterial over-
growth. For proximal and midintestinal surgery, first-
generation cephalosporins (e.g., cefazolin at 30 mg/kg
IV) should be administered. For distal small and large
intestine surgery, second-generation cephalosporins
(e.g., cefoxitin at 30 mg/kg IV) are recommended. Ide-
ally, antibiotic prophylaxis should commence preopera-
tively, approximately 30 minutes before the surgical
incision, at the time of anesthetic induction; a second
dose may be given if surgical time exceeds 1.5 hours.29
Fluid therapy aims at correcting dehydration and
improving tissue perfusion. The fluid volume and rate
of fluid administration depend on the degree of dehy-
dration and the presence of shock. Acid–base and elec-
trolyte values, if available, determine the type of fluid
to be administered. In the case of pyloric and proximal
intestinal obstruction, administration of 0.9% sodium
chloride supplemented with potassium chloride (20
mEq/L) is recommended because of possible alkalosis.
Otherwise, lactated Ringer’s solution supplemented
with potassium chloride (20 mEq/L) is the appropriate
replacement fluid.4In an experimental study of dogs
with intestinal obstruction, colloids were better than
crystalloids when large volumes of fluids were required
for volume expansion.30 Plasma oncotic pressure and
net loss of fluid into the dilated intestinal lumen were
decreased after crystalloid administration, whereas with
colloids the plasma oncotic pressure increased tem-
porarily and the jejunum was allowed to maintain nor-
mal absorptive capacity.30
A ventral midline celiotomy of sufficient length to
allow adequate inspection of the abdomen should be
performed. The FB can be localized by evaluation of the
entire intestinal tract. The most common obstruction
sites in order of frequency are the jejunum, ileum, and
duodenum.17,18 When complete intestinal obstruction is
present, marked intestinal distention proximal to the
obstruction may be seen, and congestion or cyanosis

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vided the animal is not vomiting. A bland diet is
offered in frequent, small feedings during the day. Early
food introduction may provide a source of fluids and
electrolytes and may stimulate intestinal motility.
The most common and serious complication after
FB removal is dehiscence of the enterotomy incision
with subsequent leakage of intestinal contents into the
peritoneal cavity, resulting in peritonitis. In a study of
dogs that underwent enterotomy for FB removal, the
postoperative mortality rate in the dehiscence group
was 73.7%.33 Signs of peritonitis may be vague at early
stages. Persistent vomiting, pyrexia, tachycardia,
abdominal pain, and leukocytosis may be seen and
indicate peritonitis. Diagnosis can be based on history,
clinical signs, and results of abdominocentesis or diag-
nostic peritoneal lavage. Abdominal exploration, copi-
ous lavage, resection, and anastomosis of the dehisced
segment and peritoneal drainage are the recommended
treatments.34 Dehiscence rates in small animals after FB
removal in two studies ranged from 6% to 27.7%.31,33
FB entrapment in the intestinal lumen may compro-
mise blood supply, impair intestinal integrity, and result
in dehiscence.31,33 One study found that the mean time
from surgery to dehiscence was 3.9 days, which corre-
lated well with the lag phase of intestinal healing.33 The
same study also found a significantly higher band neu-
trophil count during the first 4 to 6 postoperative days
and a higher incidence of peritonitis in the dehiscence
group when compared with a group of animals without
dehiscence. Reasons that may contribute to dehiscence
include excessive tension on the suture line, sutures
placed in nonviable tissue, poorly placed sutures, inap-
propriate suture material, traumatic tissue handling,
and excessive mucosal eversion.26,31,33 Another study
reported no difference in mortality for animals having
surgery on the small or large intestine: Both groups of
patients had the same risk for dehiscence or bacterial
peritonitis.35
LINEAR FOREIGN BODIES
Linear FBs produce a unique type of intestinal
obstruction in small animals because they may cause
serious and extensive damage to the intestinal tract.
Linear FBs are more commonly reported in cats36–38
than in dogs36,39: String and thread were found in
cats,37,38 whereas string, elastic tape, carpet, nylon
hosiery, cord, plastics, and fabrics were found in
dogs.36,39 In cats, 90.6% of FBs were thread and 9.4%
were thread and needle.38 Linear FBs initially cause a
partial intestinal obstruction; a chronic problem will
result in large portions of the small intestine becoming
damaged and nonfunctional, which leads to signs simi-
lar to those of complete intestinal obstruction.
The pathogenesis of linear FB intestinal obstruction
involves fixation of the FB at a cranial site of the diges-
tive tract. Usually, the linear FB either wraps around
the base of the tongue or is entrapped in the pylorus.
Peristaltic waves continue to move the free end of the
FB in a distal direction in the small intestine, with
resultant pleating or gathering of the intestine around
the FB. Occasionally, secondary intussusception may
occur. Intestinal pleating may be explained by the fact
that peristaltic waves cause movement of the intestine
and intestinal contents in an opposite direction. The
small intestine forms circular loops because of mesen-
teric restriction, and the linear FB, being under ten-
sion, tends to arrange in a straight line. The mesenteric
border thus becomes firm and edematous as the linear
FB is forced against the intestinal wall. Perforation of
the affected intestinal loops eventually occurs as the FB
cuts through the intestinal wall at the mesenteric bor-
der; local or generalized peritonitis ensues.4,7,36,38
Diagnosis
Clinical Signs and Physical Examination
Findings
Cats with linear FBs (mean age of 64 cats, 2.7
years38; median age of 24 cats, 1 year37) are younger
than dogs with linear FBs (mean age of 32 dogs, 4.5
years; median age, 2 years39). Vomiting and anorexia are
common clinical signs37–39; bloody diarrhea may also be
seen.4,20,38 Most affected cats may drink small amounts
of water, and in many cats the frequency of vomiting
decreased as the duration of intestinal obstruction
increased.38 Physical examination findings include
depression, fever, dehydration, abdominal pain, a
thread looped around the tongue, an FB hanging from
the mouth, an FB protruding from the anus, and pal-
pable intestinal plication.37–39 Thorough oral examina-
tion is mandatory for animals with a suspected linear
FB intestinal obstruction. An initial physical examina-
tion failed to detect the linear FB found at the base of
the tongue in 6 of 13 cats that presented with the linear
FB lodged sublingually.37 Nervous animals may need
sedation to allow thorough oral inspection. A string
was found around the base of the tongue in 50% of
affected cats in two reports,37,38 whereas only 6% of
affected dogs had a string revealed by physical examina-
tion.39 Hematologic and biochemical findings in an
animal with a linear FB intestinal obstruction are not
different from those in an animal with a nonlinear FB
intestinal obstruction.
Diagnostic Imaging
Survey abdominal radiographic findings in cats with
a linear FB intestinal obstruction include intestinal pli-

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cation, increased numbers of ec-
centrically located comma-shaped
or tapered luminal gas bubbles,
small intestinal shortening to the
right of the midline as viewed ven-
trodorsally, radiopaque FB visuali-
zation, intestinal obstruction, and
peritonitis36,38 (Figure 5). These
findings led to a tentative diagnosis
of linear FB in 54% of cats in one
study.38 In this study, however, no
radiographic abnormalities were
seen in 14% of affected cats. It was
thought that tapered bubbles pos-
sibly resulted from gas-filled intes-
tine that was corrugated around
the linear FB.38
Radiographic signs of linear FBs
in cats may be differentiated from
(1) hyperperistaltic activity result-
ing in symmetric convolutions and formation of cen-
trally located luminal bubbles in the affected intestinal
segment (linear FBs, in contrast, cause asymmetric con-
volutions and eccentrically located gas bubbles36); (2)
intestinal adhesions after previous intraabdominal sur-
gery4,36; and (3) intestinal ascarids, which appeared as
luminal linear filling defects but without intestinal
pleating.36 Findings obtained from radiography with
contrast enhancement include eccentric plication and
shortening of the small intestine, fixation of the duode-
num in pleated position, and occasional visualization of
eccentrically located gas bubbles36 (Figure 6).
Radiographic findings in dogs with a linear FB intes-
tinal obstruction were similar to those of cats. However,
on the basis of the same radiographic findings as men-
tioned above, diagnosis of a linear FB was more com-
mon in dogs (71%)39 than in cats (54%).38 In addition,
the presence of tapered gas bubbles is not a common
radiographic finding in dogs.39 Ultrasonographic exam-
ination may detect intestinal plication, which is consid-
ered diagnostic for linear FBs. However, linear FBs are
not always visualized during this examination.28
Treatment
Although most surgeons favor surgical treatment as
soon as the diagnosis of linear FB is established, conser-
vative therapy can be tried in selected feline cases.
Conservative
One study37 found that 38% of cats that have a linear
FB looped around the base of the tongue may be man-
aged conservatively, provided certain criteria are met.
The cat must be presented soon after linear FB inges-
Figure 5—Lateral abdominal radiograph of a cat with intestinal plication and tapered gas
bubbles resulting from thread and a needle in the small and large intestine, respectively.
Figure 6—Ventrodorsal radiograph of a cat after barium admin-
istration showing intestinal plication secondary to a linear FB.

Compendium November 2003 Intestinal Foreign Bodies in Dogs and Cats 841
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tion and the owner must be aware of the ingestion; if
the cat is showing no signs of peritonitis, the linear FB
that is embedded sublingually should be cut, which
may allow elimination of the linear FB in the feces
within 1 to 3 days. Hospitalization of the cat is essen-
tial for clinical, radiologic, and laboratory monitoring.
Immediate surgical intervention is warranted if the
patient’s clinical condition deteriorates or if peritonitis
or pyloric entrapment of the linear FB occurs.37
Surgical
A linear FB that is wrapped around the tongue
should be identified and released before a celiotomy.
The linear FB may be localized by identifying intestinal
plication after a midline celiotomy. Usually, a gastrot-
omy is required to release a linear FB lodged in the
pylorus, a common location in dogs, possibly because
of the large size of ingested foreign material in canine
species.39 An enterotomy is performed midway along
the site of obstruction. With the aid of a curved mos-
quito hemostat, a linear FB located in a mesenteric site
can be pulled gently and gradually until the more distal
point of fixation is reached. Another enterotomy is
made at the distal position. Multiple enterotomies,
spaced along the intestine, are required to minimize
excessive traction and avoid subsequent intestinal per-
foration and to remove the FB completely32 (Figure 7).
A single-incision technique has been described for
extraction of string in cats, provided no penetration of
the mucosa has occurred.40 An enterotomy is made to
the most proximal site of the duodenum, and the linear
FB is attached with suture to the end of a red rubber
catheter. The entire catheter is placed into the small
intestine in a proximal direction, and the incision is
closed routinely. The catheter is then milked along the
intestine, so that the plicated intestine is resolved and
the linear FB is carried along with the catheter until an
assistant retrieves it through the anus. However, failure
of this technique in a cat was reported.41
The linear FB may compromise the intestinal wall at
several sites, which can result in multiple perforations
and subsequent peritonitis. If the linear FB has been
present for a long period, localized peritonitis and
intestinal fibrosis may occur, leading to permanent pli-
cation. Those cases may be best managed with intes-
tinal resection and anastomosis. Peritonitis should be
managed as described earlier.
Intussusception was reported to accompany linear
FBs in dogs, possibly because of increased irritation by
the types of linear FBs ingested by dogs or because of
different reactions of the canine intestine to linear FBs39
(Figure 8). Enterotomies may be closed as described
earlier or by using skin staples in dogs.42 The stapling
technique reduces time at surgery and minimizes
spilling of intestinal contents during surgery.42 After
closure, the entire intestinal tract should be examined
for perforations in the mesenteric border. Fat and fibrin
deposition may mask intestinal leaks. Normal saline
injection into the isolated intestinal segment may facili-
tate detection of leakage. The abdominal cavity is thor-
oughly lavaged and is then closed in a routine fashion.
Postoperative Care, Complications,
and Prognosis
Postoperative care and complications are similar to
those for animals with nonlinear FBs. Short-bowel syn-
drome may result after resection of 90% of the small
intestine.20,26 After ileocecal valve removal, overgrowth
of bacteria that ascend from the colon may contribute
to diarrhea.20 The small intestine that remains after
extensive resection may undergo adaptation associated
with increased diameter, enlarged microvilli, and
Figure 8—Intestinal plication and intussusception secondary
to a linear FB in a dog.
Figure 7—Multiple enterotomies are required for removal of a
linear FB in a dog.

842 Small Animal/Exotics Compendium November 2003
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increased numbers of mucosal cells, the result being
increased absorption.20,26
Mortality rates after surgical removal of linear FBs
were higher in dogs (22%)39 than in cats (16%)38
because frequencies of perforations and peritonitis were
higher in dogs (31%)39 than in cats (16%).38 Moreover,
a significant prognostic indicator associated with an
increased probability of peritonitis in dogs is the pres-
ence of fabric and plastic linear FBs.39 One study
reported decreased survival of dogs and cats that under-
went more than one intestinal procedure in the same
operation.35 In addition, dogs require an increased
number of intestinal resections for linear FB manage-
ment compared with cats, possibly because of the
increased severity of intestinal trauma in dogs.39
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10. Enochsson L, Nylander G, Ohman U: Effects of intraluminal
pressure on regional blood flow in obstructed and unobstructed
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11. Cooke HJ, Reddix RA: Neural regulation of intestinal elec-
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12. Cullen JJ, Caropreso DK, Hemman LL, et al: Pathophysiology
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14. Shikata JI, Shida T, Amino K, Ishioka K: Experimental studies
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15. Summers RW, Yanda R, Prihoda M, Flatt A: Acute intestinal
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16. Prihoda M, Flatt A, Summers RW: Mechanisms of motility
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17. Capak D, Simpraga M, Maticic D, et al: Incidence of foreign-
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18. Clark WT: Foreign bodies in the small intestine of the dog. Vet
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Compendium November 2003 Intestinal Foreign Bodies in Dogs and Cats 843
CE
ARTICLE #2 CE TEST
The article you have read qualifies for 1.5 con-
tact hours of Continuing Education Credit from
the Auburn University College of Veterinary Med-
icine. Choose the best answer to each of the follow-
ing questions; then mark your answers on the
postage-paid envelope inserted in Compendium.
1. Which factors contribute to luminal distention in
complete intestinal obstruction?
a. gas accumulation
b. fluid accumulation related to hypersecretion in the
gastrointestinal tract
c. fluid accumulation related to reduced absorption in
the gastrointestinal tract
d. all of the above
2. Experimental studies of dogs with intestinal obstruc-
tion showed selective intestinal mucosal ischemia
when intraluminal pressure was
a. 10 mm Hg. c. higher than 40 mm Hg.
b. 30 mm Hg. d. 80 mm Hg.
3. Fluid and electrolyte losses in intestinal obstruction
may be the result of
a. vomiting.
b. diarrhea.
c. fluid sequestration in the intestinal lumen.
d. all of the above
33. Allen DA, Smeak DD, Schertel ER: Prevalence of small intes-
tinal dehiscence and associated clinical factors: A retrospective
study of 121 dogs. JAAHA 28:70–76, 1992.
34. Papazoglou LG, Rallis T: Diagnosis and surgical management of
septic peritonitis in the dog and cat. Waltham Focus 11:9–14,
2001.
35. Wyllie KB, Hosgood G: Mortality and morbidity of small and
large intestinal surgery in dogs and cats: 74 cases (1980–1992).
JAAHA 30:469–474, 1994.
36. Root CR, Lord PF: Linear radiolucent gastrointestinal foreign
bodies in cats and dogs: Their radiographic appearance. J Am
Vet Radiol Soc 12:45–53, 1971.
37. Basher AWP, Fowler JD: Conservative versus surgical manage-
ment of gastrointestinal linear foreign bodies in the cat. Vet Surg
16:135–138, 1987.
38. Felts JF, Fox PR, Burk RL: Thread and sewing needles as gas-
trointestinal foreign bodies in the cat: A review of 64 cases.
JAVMA 184:56–59, 1984.
39. Evans KL, Smeak DD, Biller DS: Gastrointestinal linear foreign
bodies in 32 dogs: A retrospective evaluation and feline compar-
ison. JAAHA 30:445–450, 1994.
40. Anderson S, Lippincott CL, Gill PJ: Single enterotomy removal
of gastrointestinal linear foreign bodies. JAAHA 28:487–490,
1992.
41. Muir P, Rosin E: Failure of the single enterotomy technique to
remove a linear intestinal foreign body from a cat. Vet Rec 136:
75, 1995.
42. Coolman BR, Ehrhart N, Marretta SM: Use of skin staples for
rapid closure of gastrointestinal incisions in the treatment of
canine linear foreign bodies. JAAHA 36:542–547, 2000.

844 Small Animal/Exotics Compendium November 2003
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4. Vomiting in a dog with distal intestinal obstruction
may result in
a. metabolic alkalosis.
b. metabolic acidosis.
c. hypokalemic metabolic alkalosis.
d. hypochloremic metabolic alkalosis.
5. Which antibiotic is recommended for prophylactic use
in surgery on the large intestine?
a. cefalexin c. cefazolin
b. cefoxitin d. cefadroxil
6. Which characteristic is not used for assessment of
intestinal viability?
a. wall thickness
b. wall color
c. appearance with IV fluorescein dye
d. arterial pulsations
7. ________ may increase the possibility of dehiscence
after enterotomy closure.
a. Minimal mucosal eversion
b. Excessive mucosal eversion
c. Atraumatic tissue handling
d. Lack of tension on the suture line
8. Cats with linear FB ingestion may be managed conser-
vatively if they
a. present soon after ingestion and have no signs of
peritonitis.
b. show signs of acute abdomen.
c. show signs of pyloric obstruction.
d. have chronic hemorrhagic diarrhea.
9. Which approach is not recommended for enterotomy
closure?
a. simple continuous approximating suture pattern
b. simple interrupted approximating suture pattern
c. skin staples
d. wound glue
10. In patients with linear FBs, intestinal resection and
anastomosis are recommended for treatment of
a. multiple perforations and subsequent peritonitis.
b. intestinal fibrosis and permanent plication.
c. extensive intestinal wall compromise.
d. all of the above