Obstructive pathologies of the oesophagus include oesophageal foreign bodies, oesophageal stenoses, anomalies of the vascular ring, oesophageal neoplasms and gastro-oesophageal intussusception. Oesophageal foreign bodies are relatively common in the dog and rare in the cat. Bones and bone fragments are the most frequent foreign bodies (Fig. 1). This pathological condition, if not diagnosed and treated promptly, can have fatal consequences and does, therefore, represent a true clinical emergency.
SIGNALMENT
Oesophageal foreign bodies are found mostly in small or medium-sized young dogs, although adult and elderly animals can also easily ingest foreign bodies if they find themselves in a conducive situation. Large or giant dogs less frequently suffer from signs of obstruction due to foreign bodies, unless these latter are really big. Recently there was a report1 of 31 cases of oesophageal obstruction due to a chlorophyll-based chew, used for dental treatment in small or toy-sized dogs; of these 31 dogs, 87% weighed less than 10 kg.
CLINICAL SIGNS
When there is a description of the ingestion of a bone or other foreign body, the diagnosis is easy. Typically the owner reports that the dog was disturbed or threatened while chewing something and decided to swallow it thus causing the obstruction. If, however, there is no history, the onset and manifestation of the clinical signs can be non-specific and difficult to identify. Regurgitation is the main clinical sign, but can be missed in some cases if masked by the patient living with other animals. As in all oesophageal obstructive disorders, the regurgitation typically occurs immediately after eating food. Some subjects show only anorexia, depression or sialorrhoea. Vomiting may occur in some animals, particularly those in which the foreign body is in the cardia, straddling the oesophagus and stomach. Some dogs can keep down liquids, but not food. In any case, the clinical signs, particularly regurgitation when present, worsen progressively and respond, at best, only partially to medical treatment.
The factors that most strongly influence the clinical presentation and therapeutic management of oesophageal foreign bodies are the shape of the foreign body, its site and the duration of the obstruction. The shape influences the occurrence of the obstruction in that a foreign body with irregular and/or sharp surfaces causes trauma to the mucosa and is consequently trapped by the damaged mucosa. This happens, for example, when the foreign body is a bone and, in particular, a vertebra which, because of its spinal process, injures the mucosa and becomes lodged in it. In the case of fishhooks (Fig. 2) with the line still attached, it is the owner’s attempt to withdraw the object that transfixes the hook. This occurs typically, but not exclusively, in the cardia. Large foreign bodies (Fig. 3) cause obstruction through their bulk, even if they have smooth surfaces. The position of the foreign body is influenced by the anatomy of the oesophagus which, although capable of very considerable dilatation, cannot expand in some points of its course. For this reason the superior oesophageal sphincter, the entrance into the thorax, the peri-cardiac portion and the pre-cardial portion are the most common sites for lodgement of foreign bodies.
DIAGNOSIS AND TREATMENT
Radiological studies are usually diagnostic. If the foreign body is radio-opaque it is easily identified on latero-lateral X-rays of the neck and thorax. Even if the foreign body is not radio-opaque, the radio-transparency of the lungs acts as a useful contrast. Despite this, in some cases, particularly those involving rabbit or chicken bones, which are only weakly radio-opaque, X-rays may not enable a certain diagnosis. Superimposition can make it difficult to identify foreign bodies, particularly those located under the costal arch (Fig. 4a and b). In doubtful cases it is advisable to take other projections, including a dorsoventral one, and use contrast agents. Barium sulphate is an excellent aid (Fig. 5), although if there is any suggestion that there may be oesophageal perforation or if the purpose of the investigation is to locate a perforation, iodinated contrast agents must be used. An ultrasound examination is rarely useful for resolving diagnostic doubts about the presence of an oesophageal foreign body, since the air in the lungs prevents the transmission of the echoes.
Endoscopy is of fundamental importance for both the diagnosis and treatment of patients with a foreign body2,3. Endoscopic removal of the foreign body is the treatment of choice. To this end, rigid endoscopes and flexible endoscopes and videoendoscopes can be used and there are also reports of the possibility of removing the foreign body without direct vision, under fluoroscopic guidance4. The therapeutic success is dependent on the use of appropriate ancillary instruments, which are: Dormia snares, internal and external grasping forceps (laparoscopy forceps) (Fig. 6), type S-G rigid dilators and pneumatic dilators. The endoscopic technique comprises a first phase in which the operator views the foreign body and frees it from any food, saliva and detritus, which often accumulate cranially to a foreign body. For this purpose, the same forceps employed in the second phase or an external aspirator, attached or not to the endoscope, can be used. The second phase is more important because it is aimed at dislodging the foreign body from where it is causing an obstruction; Dormia or external grasping forceps anchored to the foreign body (Figs. 7 and 8) can be used with traction and to and fro movements to mobilise the foreign body.
When the foreign body seems to be less firmly attached, the operator can extract it through the oral cavity or displace it into the gastric cavity (Figs. 9 and 10). This latter option is preferable, or at any rate acceptable, when the foreign body is a bone and located in the pre-cardial part of the oesophagus and when the mucosa is severely damaged; in this condition cranial retraction is more uncertain and could cause further damage or mucosal perforation. Bone undergoes rapid decalcification following dislodgement into the stomach. Serrated (‘mouse’s teeth’) forceps are necessary to extract fishhooks (Fig. 11). The jaws of the forceps must grasp the curved part of the hook, which is then pushed caudally with the same movement used during “unhooking” a fish. If the fishing line is attached to the hook, this latter can be extracted using a rigid tube that acts as a disgorger: this procedure can be carried out blind or under endoscopic vision. Once the foreign body has been extracted, it is important to check the conditions of the oesophageal mucosa which usually has erosions and ulcers of variable size and severity (Fig. 12); if there is a perforation of the mucosa, its extent must be evaluated in order to determine whether to manage the problem with a conservative medical approach or surgery. The oesophagus is an organ with notable regenerative capacity and there are reports of perforations longer than cm which have resolved spontaneously with only functional rest.
In this author’s opinion, blind extraction of foreign bodies under fluoroscopic guidance should be a second-choice technique and definitely carries a higher risk than extraction under direct vision. If endoscopic removal of the foreign body is not successful, surgical asportation can be performed5. This is relatively simple if the foreign body is in the cervical oesophagus, while it is more complex if a thoracotomy is necessary for the surgical access. In all cases, it is easier to remove a foreign body from the stomach than from the oesophagus.
In cases in which the foreign body causes perforation and rupture of the oesophagus, the animal shows clinical signs of mediastinitis such as fever, tenderness and difficulty in breathing. This condition can also be detected in its late stages by radiological studies (Fig. 13), while in the earlier stages the patient may only show fever and asthenia. The evolution towards the development of a septic pleural effusion is fast and the patient’s prognosis is very poor. Following endoscopic removal of a foreign body, the patient should be given broad-spectrum antibiotics and an anti-H2 antacid (ranitidine 2-4 mg/kg bid per os). If the mucosal damage is severe, sucralfate can be used in the days following the removal of the foreign body; if complete inhibition of gastric acid is desired, proton pump inhibitors can be administered (omeprazole 0.7 mg/kg sid per os).
The outcome of patients with oesophageal foreign bodies is generally good; there is rapid clinical improvement and resolution of the regurgitation. However, following removal of a foreign body, whether endoscopically or surgically, a benign, intramural, fibrotic stenosis may develop. Indeed, if the patient shows regurgitation within 5-15 days after the removal of the foreign body, a stenosis should be suspected and the patient subjected to an endoscopic examination for diagnostic and therapeutic purposes.
References
- Esophageal foreign body obstruction caused by a dental chew treat in 31 dogs (2000-2006).Leib MS, Sartor LL. J Am Vet Med Assoc. 2008 Apr 1;232(7):1021-5
- Studio retrospettivo su 23 casi di corpi estranei ossei a sede esofagea nel cane e nel gatto trattati per via endoscopica. Bottero E., Bertoncello D., De Lorenzi D Veterinaria, Anno 21, n. 4, Agosto 2007
- Oesophageal and gastric endoscopic foreign body removal: complications and follow-up of 102 dogs. Gianella P, Pfammatter NS, Burgener IA. J Small Anim Pract. 2009 Dec;50(12):649-54
- Removal of oesophageal foreign bodies in dogs: use of the fluoroscopic method and outcome. Moore AH J Small Anim Pract. 42(5): 227-230, 2001
- Results of transthoracic esophagotomy retrieval of esophageal foreign body obstructions in dogs: 14 cases ( 2000-2004). Sale CS, Williams JM:J Am Anim Hosp Assoc. 2006 Nov-Dec;42 (6): 450-6.