Magnet Ingestion in Dogs: Two Cases
Two dogs that had ingested foreign bodies were presented with vomiting. The foreign bodies appeared as metal and dense on abdominal radiographs. Abdominal exploratory identified intestinal perforation in one case and gastrointestinal tissue trapped between the two foreign bodies adhered to each other in the second case. The foreign bodies were identified as magnets in one case and magnets and other metallic foreign bodies in the second case. Both dogs had excellent outcomes following surgical intervention. These cases demonstrate the danger of tissue entrapment between the foreign bodies as a result of the magnetic attraction between two objects. Dogs that are presented with a history of or are suspect for ingesting multiple magnets or a magnet and metal foreign bodies should be treated with surgical intervention because of the risk of gastrointestinal perforation as a result of magnetic attraction between the foreign bodies.
Introduction
Foreign body ingestion is a common occurrence in veterinary medicine and often presents the clinician with difficulty in selecting the most appropriate therapy. Many animals that are presented with clinical signs consistent with obstruction but without diagnostic evidence (i.e., radiographs, contrast studies, ultrasound) of obstruction typically undergo surgical intervention only when medical management fails. Determining the appropriate timing for surgical intervention can be frustrating for the attending clinician, as a delay in surgery may result in intestinal perforation and sequelae such as septic abdomen and gastrointestinal necrosis. The following cases are presented to assist the clinician in management of dogs that have ingested magnetic foreign bodies.
Case Reports
Case No. 1
A 9-month-old, neutered male, Yorkshire terrier mix was admitted to Pet Central Animal Hospital in Minneapolis, Minnesota, for vomiting of 2 days’ duration. Physical examination was unremarkable. The owners were suspicious that the dog had ingested a foreign body, and they administered barium sulfate suspension (obtained from a family member employed within the veterinary field) per os (PO) the day prior to presentation. The dog vomited once following barium administration.
Abdominal radiographs [Figures 1, 2] were taken at the time of admission. Contrast material was present within the large intestine, but it had cleared the remainder of the gastrointestinal tract. A single, small, metal, dense foreign body (1.3 cm × 1.3 cm) was apparent. On the ventrodorsal view, the density appeared to be within the colon; however, on the lateral view, the foreign body appeared to be within the small intestine. The dog was admitted to the hospital for observation and radiographic reexamination. The dog defecated within 12 hours of admission, and orthogonal abdominal radiographs were repeated immediately after defecation [Figures 3, 4]. The second series of radiographs revealed that the contrast material had completely cleared the gastrointestinal system, but the radiodense foreign object remained in the same anatomical location as previously noted.
An exploratory laparotomy was performed. At surgery, the pylorus was adhered to the colon just aborad to the cecum, and hard foreign bodies were palpable within the lumen of both the pylorus and the colon at the site of the adhesion. The pylorus and colon were separated with blunt dissection, and the serosal surfaces of both the colon and pylorus at the adhesion site were black in color and necrotic in appearance. A partial gastrectomy at the site of tissue damage was performed, and a metallic foreign body was removed. A colotomy with debridement at the site of the compromised tissue was performed, and a second metallic foreign body was removed. The purpose of the colotomy was to address the presence of necrosis rather than to remove the foreign material. Both sites were closed with 3-0 polydioxanone (PDS)a in a simple interrupted pattern.
The dog recovered uneventfully from surgery. One dose of penicillinb was administered intraoperatively (150,000 U/kg intravenously [IV]), and amoxicillinc was administered PO at 20 mg/kg q 12 hours for 10 days, along with carprofend PO at 1.5 mg/kg q 12 hours for 7 days. The foreign bodies were determined to be two magnets, each approximately 1 cm × 1 cm, that appear to have been attracted to each other in the abdomen. They were suspected to have created enough of a magnetic force to cause pressure necrosis of the tissues trapped between them. Examination of the dog at the time of suture removal (10 days postoperatively) was unremarkable, and the dog was reported to be doing well at home.
Case No. 2
A 1-year-old, intact female basset hound was presented to Red Bank Veterinary Hospital in Red Bank, New Jersey, for vomiting of 2 days’ duration. On physical examination, the dog exhibited pain upon palpation of the cranial abdomen. The remainder of the examination was unremarkable. A complete blood count and serum biochemical panel revealed mild hypokalemia (3.4 mmol/L, normal reference range 3.5 to 5.8 mmol/L). All other values were within normal limits.
Abdominal radiographs [Figures 5, 6] showed several metallic foreign bodies of varying shapes in both the small and large intestines. Moderately dilated loops of small intestine were present in the caudal abdomen. The owner believed the foreign bodies to be staples, ball bearings, and magnets. Because of the dog’s clinical presentation and history of foreign body ingestion, an exploratory laparotomy was performed. One object was palpated within the jejunum; the other foreign bodies were palpated in the colon. A 0.8-cm, antimesenteric, jejunal perforation at the site of the palpable foreign body was identified. Omentum was adhered to the site of perforation. The colon appeared grossly normal, and no gross evidence of peritonitis was present. A jejunal resection and anastomosis at the site of perforation and removal of the foreign body were performed using 4-0 PDS in a simple interrupted pattern. Omentum was tacked over the site with 4-0 PDS.
The dog recovered uneventfully from surgery. Cefazoline was administered intraoperatively at 30 mg/kg IV and continued q 8 hours postoperatively for three doses. Cephalexinf was administered PO at 30 mg/kg q 8 hours for 14 days following surgery. The foreign bodies within the colon were recovered after the dog defecated; they were confirmed to be staples, ball bearings, and magnets. Examination at the time of suture removal 7 days postoperatively was unremarkable, and the dog was reported to be normal at home. Although not obvious at the time of surgery, it was suspected that magnetic attraction between two magnets (or between a magnet and a ball bearing) with interposition of the intestine had occurred at some time, resulting in the jejunal perforation.
Discussion
To the authors’ knowledge, magnet ingestion by dogs has not been reported in the scientific literature; however, multiple cases involving human pediatric patients have been reported.1–13 Ingestion of a single magnet alone is unlikely to create problems. Multiple magnets, however, or a magnet ingested with other metallic foreign bodies, present a potential danger when passing through the gastrointestinal tract, as observed in the two case reports described herein.
Complications associated with ingestion of multiple magnets (or a magnet and another metallic foreign body) in human medicine include bowel perforation,1–6 fistula formation,4,7–13 mesenteroaxial torsion,6,11 internal herniation with strangulation,1,12,13 and even death.6 All cases were identified as having radiopaque foreign bodies on abdominal radiographs. One study reported that 91% of all cases had enteroenteric fistula formation or bowel perforation. In one study, 82% of the human cases had radiographic evidence of intestinal obstruction.1 Another study reported that only 20% of cases had bowel obstruction, but 15% had intestinal volvulus and 75% experienced bowel perforation.6 In some case reports, the ingestion of one magnet with a nonmagnetic metallic object resulted in intestinal perforation.2,3,6
One human fatality has been reported as a result of magnet ingestion,6 and multiple cases requiring surgical intervention have been reported.1–13 Many of the human patients were old enough to convey that a magnet had been ingested; however, a few patients were too young to communicate.3,4,7,9,10 In these latter cases, either the patients’ parents were suspicious of magnet ingestion or the magnets were discovered at the time of surgery. The likelihood in veterinary medicine is that magnet ingestion will not be discovered until the time of surgery.
Unless an owner has witnessed the foreign body ingestion or has reason to suspect magnet ingestion, the increased risk to the animal may not be apparent until perforation or fistula formation has occurred. The Centers for Disease Control and Prevention (CDC) recommend the use of a magnetic compass placed near the patient’s body to observe for magnetic field disturbance in cases where magnet ingestion is suspected.6 Given the possible variations in the strength of different magnets, the authors suspect that a lack of an observable magnetic field disturbance does not rule out magnet ingestion, but an observable disturbance in the magnetic field warrants concern.
If magnet ingestion is a top differential of a presented animal, and radiographic evidence shows ingestion of metallic, dense foreign bodies, the clinician should proceed aggressively. The current standard of care in human medicine pertaining to foreign body ingestion is to remove any obstructive, gastric foreign material endoscopically.8,14 If the foreign material is not within reach of an endoscope, the patient is closely monitored for clinical symptoms of obstruction or peritonitis, with serial radiographic monitoring of the progression of the foreign object. Specifically concerning magnetic foreign body ingestion, endoscopic removal of gastric foreign bodies is recommended as well, while emergency surgery is recommended if the foreign body cannot be removed or if the magnetic foreign body is in the small intestine.8 As evidenced by case no. 1 described herein, one must be cognizant that even if only one foreign body is apparent radiographically, the foreign body could in fact be two magnets adhered to each other that simply appear to be only one object [Figures 1, 2, 3, 4]. If aboral progress of the foreign body ceases or the animal develops symptoms consistent with gastrointestinal obstruction or peritonitis, the clinician should not hesitate to proceed with surgical intervention.
The cases presented here demonstrate that the clinical concerns associated with magnet ingestion in humans are shared by veterinarians. Entrapment of tissues between the magnets resulted in significant tissue damage and arrest of the passage of the foreign bodies in one case. Since only one source of tissue damage was identified in the second case, it is possible that migration of a single foreign body across the intestinal wall, or pressure necrosis from a foreign body wedged at that site, could have caused the observed tissue damage (i.e., perforation). The absence of a foreign body free within the peritoneal cavity or of an obstructive foreign body at the site of perforation, coupled with the presence of magnets and other metallic foreign bodies, makes damage as a result of magnetic attraction the most likely differential.
Conclusion
Given the two veterinary cases presented here, it appears prudent to adopt the standard of care used in human medicine for management of animals that have ingested magnetic foreign bodies. If magnet ingestion is suspected, aggressive monitoring should be followed by exploratory surgery if arrest of a metallic foreign body occurs, even in the absence of pain on abdominal palpation.
PDS II polydioxanone suture; Ethicon, Inc., a Johnson & Johnson Company, Somerville, NJ 08869
Penicillin; Phoenix Scientific, Inc., St. Joseph, MO 64503
Amoxicillin, Amoxi-Tabs; GlaxoSmithKline, Research Triangle Park, NC 27709
Carprofen, Rimadyl Chewables; Pfizer Animal Health, New York, NY 10017
Cefazolin; Schein Pharmaceuticals, Inc., Florham Park, NJ 07932
Cephalexin; IVAX, Miami, FL 33127
Citation: Journal of the American Animal Hospital Association 46, 3; 10.5326/0460181
Citation: Journal of the American Animal Hospital Association 46, 3; 10.5326/0460181
Citation: Journal of the American Animal Hospital Association 46, 3; 10.5326/0460181
Citation: Journal of the American Animal Hospital Association 46, 3; 10.5326/0460181
Citation: Journal of the American Animal Hospital Association 46, 3; 10.5326/0460181
Citation: Journal of the American Animal Hospital Association 46, 3; 10.5326/0460181
Initial lateral radiograph (case no. 1) reveals barium present within the colon, and a metal, dense foreign body appears to partially overlay the colon.
Initial ventrodorsal radiograph (case no. 1) shows the metal, dense foreign body completely overlaying the colon.
Repeat lateral radiograph (case no. 1) reveals that barium completely cleared the gastrointestinal tract, but the metal, dense foreign object appears to remain in the same position.
Repeat ventrodorsal radiograph (case no. 1) shows imposition of the metal, dense foreign body over the colon at previously noted site.
Lateral radiograph (case no. 2) identifies multiple, metal, dense foreign objects clustered in the central abdomen.
Ventrodorsal radiograph (case no. 2) reveals multiple, metal, dense foreign objects in the cranial central abdomen.
