Introduction

Penetrating injuries to the oral cavity and pharyngolaryngeal area from foreign objects are sometimes seen in dogs^1-3 that chew on or carry and retrieve sticks and ^are seen rarely in cats⁴. Commonly affected areas include the sublingual area, lateral pharyngeal wall and tonsillar crypt, soft palate and dorsal esophageal wall. In one study, the most common site of injury was sublingual.² Symptoms, clinical approach, and treatment options vary depending on the acute or chronic presentation of the patient, the exact location of the trauma and the severity of it.

Symptoms

Pharyngeal trauma is often witnessed by the owner, though most do not seek medical help immediately.² Common presenting complaints in the acute stage are dysphagia, drooling, depression, oral pain, pain on flexion of the neck, subcutaneous emphysema in the cervical region, blood in the saliva, and pain on opening of the mouth.⁵ Cases with chronic penetrating stick injuries present with a recurrent swelling or abscess of the head or neck, with or without a cutaneous draining sinus in the cervical region.

Diagnosis

The management of acute penetrating pharyngeal stick injury is primarily directed at emergency stabilization of the patient and diagnostic workup should be delayed until the patient has been stabilized. Animals can present in severe dyspnea as a result of pharyngeal swelling or mediastinal emphysema. Hypoxia, hypovolemia, and shock should be addressed prior to further workup.

Plain radiographs of the head, neck, and thorax are recommended for initial diagnostic workup in animals with a suspected or confirmed acute penetrating injury to the throat or esophagus.^1-3 Subcutaneous emphysema, gas between fascial planes in the cervical region, confirms that penetration has occurred and can help localize the injury.⁵ However, this gas can dissect away from the original leakage along fascial planes, causing pneumomediastinum or pneumothorax, making localisation difficult.^1,2 Despite being helpful for assessment of the degree of trauma and for localisation, the stick itself or fragments do not show on radiographs. Ultrasonography of the throat or neck is not of great use in the acute patient either for this purpose since subcutaneous emphysema can mask small foreign bodies.⁶ Advanced imaging techniques as computed tomography (CT) and magnetic resonance imaging (MRI), have not been evaluated for use in pharyngeal stick injury in patients with an acute presentation.

Consistent radiographic abnormalities were not seen in patients with chronic presentations,³ but sinography, though only applicable in cases with external draining sinuses, appeared to have a high sensitivity and specificity for identification of foreign bodies⁷. Ultrasonography has been reported to be a valuable aid as well in identification of abscesses and wooden foreign bodies in patients with a chronic presentation, is relatively cheap and can usually be performed without anesthesia.^8,9 Most foreign bodies are easily recognized when surrounded by exudative fluid. Though only evaluated in small case series, computer tomography with or without IV contrast and MRI are very accurate in recognizing wood foreign bodies.^10,11 Depending on the water content of the different layers of the sticks, the foreign bodies show a variable attenuation pattern on CT.¹¹

General anesthesia permits thorough examination of the entire oral cavity and inspection of the pharynx, larynx, and rostral esophagus. With the dog in sternal recumbency and before endotracheal intubation, careful examination of the sublingual areas on the left and right of the frenulum, of the tongue base, the lateral pharyngeal walls and tonsillar crypts, and hard and soft palate needs to be performed. After inspection of the larynx, an endotracheal tube can be inserted to secure the airways. After rostral retraction of the soft palate and inspection of the caudal nasopharynx and laryngopharynx, a long laryngoscope blade can be advanced into the rostral esophagus. When perforations are not found at this time, complete cervical esophageal endoscopy is advised. The site of penetration is frequently not apparent though, especially in chronic cases. When a piece of wood is visible in the soft tissues, withdrawal is not recommended because of the risk of fragmentation.⁶ Small perforations in the oral cavity to the level of the oropharynx that can be fully inspected and flushed and do not contain foreign material, do not have to be explored surgically but can be left to heal by second intention. In all cases of perforations of the caudal pharyngeal (laryngopharynx) or esophageal wall, surgical exploration of the neck via a ventral midline approach is recommended. A logical decision as to whether or not surgery is indicated also depends on the point of entry and direction of the stick injury. Trauma in the direction of the dorsal nasopharynx (usually through the soft palate) and brain cannot be explored via a ventral neck approach. Diagnostic imaging findings will help aid in surgical planning in patients with chronic presentations and abscesses. In most of these patients a midline ventral neck approach is indicated as well.

Surgery

Surgical exploration of the retropharyngeal space is accomplished through a ventral midline approach from hyoid apparatus to the manubrium of the sternum with the patient in dorsal recumbency and with a support under the neck. A probe or sterile catheter may be inserted at the oral perforation site to help identification and direction of the penetration tract. A gastric tube is very helpful for identification of the esophagus, yet needs to be carefully inserted as not to enlarge any possible tears. The goal is to locate and remove foreign material, obtain tissue or fluid samples for cytology and culture, debride nonviable tissue, and establish drainage if necessary.⁵ The exploration is started in the distal neck area and extended rostrally, working from unaffected (clean) towards affected (dirty) tissues.⁶ The laryngeal area should be explored with great care to avoid disruption of the recurrent laryngeal nerves or pharyngeal plexus during dissection. Stay sutures in the laryngeal cartilages can help visualise pharyngolaryngeal perforations and rostral esophageal lesions. Stay sutures in the esophageal wall can be used if necessary as well to rotate the esophagus and aid in accurate suture placement. After local debridement, the esophageal tear is sutured in one or two layers with PDS. A local muscular flap can be used as "muscular patch" to improve wound healing. After exposure of the penetration tract and after removing the foreign bodies, the tract is flushed with saline, and the surgical wound is sutured over a drain. Drainage can be active or passive, passive drains should exit in a dependent direction through a separate incision. A gastrostomy feeding tube is recommended after esophageal repair to bypass the area and avoid contamination of the wound with food particles. Empirical administration of antibiotics is usually indicated if infection is suspected.⁵ Therapy can be modified after culture and sensitivity results are available.

Prognosis and Complications

Acute penetrating injury of the oropharyngeal region, when treated appropriately, has a good prognosis with most or all patients making a complete recovery.^1-3 Acute injuries to the oropharyngeal region have a better prognosis than acute esophageal penetrations.¹ The most common postoperative complication of the latter is septic mediastinitis and death. Clinical signs resolved in 62% of dogs that presented with chronic signs in one large study.² Aggressive surgical debridement of all sinus tracts is essential in obtaining a successful result, but recovery of a foreign body is not necessarily a determinant of success.²

References

1.  Doran IP, Wright CA, Moore AH. Acute oropharyngeal and esophageal stick injury in forty-one dogs. Veterinary Surgery. 2008;37(8):781–785.

2.  Griffiths LG, Tiruneh R, Sullivan M, Reid SW. Oropharyngeal penetrating injuries in 50 dogs: a retrospective study. Veterinary Surgery. 2000;29(5):383–388.

3.  White R, Lane JG. Pharyngeal stick penetration injuries in the dog. The Journal of Small Animal Practice. 1988;29(1):13–35.

4.  Bright SR, Mellanby RJ, Williams JM. Oropharyngeal stick injury in a Bengal cat. Journal of Feline Medicine and Surgery. 2002;4(3):153–155.

5.  Anderson GM. Soft tissue of the oral cavity. In: Tobias KM, Johnston SA, eds. Veterinary Surgery Small Animal. St. Louis, MO, USA: Elsevier Saunders; 2012: 1425–1438.

6.  Peeters ME. The Management of pharyngeal stick penetrating injuries in dogs. In: Proceedings from the European Veterinary Conference Voorjaarsdagen (Abstracts); 2010: 1–2.

7.  Lamb CR, White RN, McEvoy FJ. Sinography in the investigation of draining tracts in small animals: retrospective review of 25 cases. Veterinary Surgery. 1994;23(2):129–134.

8.  Armbrust LJ, Biller DS, Radlinsky MG, Hoskinson JJ. Ultrasonographic diagnosis of foreign bodies associated with chronic draining tracts and abscesses in dogs. Veterinary Radiology & Ultrasound. 2003;44(1):66–70.

9.  Staudte KL, Hopper BJ, Gibson NR, Read RA. Use of ultrasonography to facilitate surgical removal of non-enteric foreign bodies in 17 dogs. The Journal of Small Animal Practice. 2004;45(8):395–400.

10. Dobromylskyj MJ, Dennis R, Ladlow JF, Adams VJ. The use of magnetic resonance imaging in the management of pharyngeal penetration injuries in dogs. The Journal of Small Animal Practice. 2008;49(2):74–97.

11. Nicholson I, Halfacree Z, Whatmough C, Mantis P, Baines S. Computed tomography as an aid to management of chronic oropharyngeal stick injury in the dog. The Journal of Small Animal Practice. 2008;49(9):451–457.