Small Animal Surgical Emergencies. Группа авторов

constant rate infusion, CRI; cats loading dose 1 μg/kg, maintenance 1–5 μg/kg/hour CRI) or morphine–lidocaine–ketamine infusions are sometimes indicated (see Chapter 1, Table 1.3 for detailed information on analgesia). Bupivacaine is a local anesthetic agent of relatively long duration used to block intercostal nerves during surgery. It can be diluted and administered into the pleural space, via the thoracic drain, postoperatively. The author uses a 0.25% solution at 2 mg/kg diluted to a volume that will adequately distribute to bathe the intercostal incision (i.e., 5–10 ml depending on the animal's size). Administration begins around six hours postoperatively, once the intercostal block performed at the time of surgery wears off. Non‐steroidal anti‐inflammatory drugs (NSAIDs, e.g., meloxicam 0.2 mg/kg IV loading dose, then 0.1 mg/kg daily from day 2 to day 5) may be indicated for patients that are not hypotensive, azotemic, or suffering from gastroenteritis. Acetaminophen (10 mg/kg IV every 12 hours) provides adjunctive analgesia in dogs and may be combined with NSAIDs. Acetaminophen is toxic to cats. Omeprazole (0.5–1.5 mg/kg IV every 24 hours) and sucralfate (500 mg–2 g/dog orally every 8 hours) are used to treat or prevent the establishment of esophagitis, reduced lower esophageal sphincter tone, and gastroesophageal reflux, which can contribute to patient morbidity, and the risk of subsequent esophageal stricture formation. Because these patients are at risk for aspiration pneumonia, broad‐spectrum antibiotics (e.g., cefuroxime 10–15 mg/kg every 8–12 hours) are indicated. Regular monitoring of respiratory status via clinical examination, pulse oximetry measurement, arterial blood gas analysis, and by thoracic imaging, if indicated, should be performed. Chest tubes are normally maintained for 12–24 hours. The timing of removal depends on the volume and nature of drain egress as well as any continuing need for a route of interpleural administration of local anesthetic agents. Endoscopically placed gastrostomy tubes are maintained for a minimum of 10 days, to allow an adhesion to form between the stomach and body wall. Surgically placed gastrostomy tubes may be removed at any time, because the stomach is pexied to the body wall by sutures. Gastrostomy tubes may be useful in the administration of postoperative nutrition and medications.

Complications

      Early complications following foreign body removal can include esophagitis, ischemic necrosis, dehiscence, leakage, and infection. Esophageal strictures can arise as a late complication and are outside the scope of this chapter. It is the author's impression that this occurs more commonly after esophagotomy than after nonsurgical foreign body retrieval. Tracheoesophageal and bronchoesophageal fistulae are other, rare late complications.

Prognosis for Esophageal Bone Foreign Bodies

      A population of 223 dogs with esophageal bone foreign body was reviewed by Brisson et al. in 2018 [18]. While older animals, a longer duration of foreign body entrapment, and the presence of esophageal perforation were associated with a poorer prognosis, the overall findings were encouraging. Endoscopic retrieval or advancement to the stomach was achieved in 183 of 219 dogs in which it was attempted. Only 16 of 143 entrapments were associated with formation of an esophageal stricture.

Fishhooks and Needles

      Both fishhooks and needles are regularly found lodged in the esophagi or periesophageal tissues of dogs and cats. These foreign bodies do not pose an immediate risk to the animal, but they are a source of distress and provoke dysphagia and anorexia in most individuals. Many of these cases can be managed endoscopically, using a suitable gastroscope, such as the GIF XQ230 gastroscope (9.8 mm external diameter, 2.8 mm diameter biopsy channel).

      Fishhooks

Fishhooks may rest free within the esophageal lumen or their barbs may engage the esophageal wall (Figure 4.13). A review of endoscopic and surgical retrieval of fishhooks in a population of dogs and cats reported successful endoscopic retrieval in 23 of 36 cases of esophageal fishhooks [19]. Single barb hooks are more readily retrieved than treble barbed hooks [19]. Body size, elapsed time since hook ingestion, and hook shaft orientation are not significantly correlated with the probability of successful retrieval [19].

Figure 4.13 Radiograph demonstrating a large fishhook within the thoracic esophagus. The clinician must be mindful of the risk of laceration of great vessels during retrieval attempts.

      Two methods are commonly employed during endoscopic retrieval:

      1 Advance the hook into the stomach, rotate the hook shaft 180 degrees, such that the barb(s) are pointing aborally, and then regrasp the shaft for withdrawal. This ensures that the barbs do not catch the esophageal wall during hook retrieval up the esophagus. Endoscopic grasping forceps are appropriate for hook manipulation.

      2 Use a hook disgorger. These can be obtained through fishing suppliers, but they can also be improvised using tubing of suitable diameter and stiffness. The author employs a narrow‐bore stomach tube (Figure 4.14). A line must already be attached to the hook and the client should be advised in advance not to cut any line which protrudes from the animal's mouth but instead to tie this line to the animal's collar. The animal is anesthetized, and the disgorger is fully advanced over the line. The line must be regrasped before the disgorger enters the esophagus. It is often necessary to tie a second line to the end of the first to give adequate length to regrasp the line. Mild tension is maintained under endoscopic visualization. Once the disgorger reaches the hook, the operator applies a firm push on the disgorger which disengages the barb from the esophageal wall. Maintaining firm tension on the line to seat the hook within the tip of the disgorger leaves little opportunity for the barbs to protrude and reengage the esophageal wall. The hook, line, and disgorger are withdrawn as one unit.

      The proximal esophagus may prove difficult to inflate, as insufflated air readily exits via the esophageal aditus, rendering visualization difficult. The author has occasionally used long Rochester Pean artery forceps alongside a rigid esophagoscope to retrieve very proximally located hooks.

Figure 4.14 (a) Endoscopic view (looking distally) of a fishhook within the esophagus. The tip of the fishhook is engaging the esophageal wall. (b) A disgorger (narrow‐bore stomach tube) can be advanced over the fishing line to rest against the hook. The operator will thrust the disgorger to disengage the barb of the hook from the esophageal wall.

      The most common complication associated with endoscopic retrieval is mild mucosal laceration and this seldom requires further treatment. Reports of fatal pulmonary vein laceration during endoscopic hook retrieval exist [19].

      Surgical retrieval is indicated where endoscopic retrieval attempts fail or where gross esophageal tearing is identified. The surgeon adopts a ventral midline cervical approach or a lateral intercostal thoracotomy centered over an appropriate intercostal space. An esophagotomy is then often required, although some hooks may be retrieved endoscopically once the surgeon has snipped off a barb that penetrates the esophageal wall [19].

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