Head and Neck Swelling Due to a Circumferential Cicatricial Scar in a Dog

Introduction

Anecdotal reports of circumferential cervical foreign bodies—such as collars that are placed too tightly, rubber bands, string, etc.—are not uncommon. Many times, the only complications resulting from these objects are skin abrasions and secondary infections. Only two reports are known of circumferential cervical foreign bodies causing acute respiratory effort and dysphagia.^1,2 This case report describes the features and management of long-term complications that appeared 2.5 years after a circumferential cervical foreign body was removed. Other differential diagnoses for head and neck swelling are also discussed.

Case Report

A 4-year-old, castrated male, mixed-breed dog weighing 26.4 kg was referred to The University of Tennessee Veterinary Teaching Hospital for head and neck swelling and increased respiratory effort. The owners had found the dog when it was approximately 6 months old; at that time, a rubber band and string were seen entwined around the dog’s neck. The rubber band and string had eroded through the skin and subcutaneous tissues of the neck, and the surrounding tissues appeared necrotic. The owners had removed the rubber band and string using a pocketknife, and the dog appeared to heal completely. The dog was clinically normal for the next 2.5 years.

Six months before presentation at the authors’ hospital, the dog developed moderate exercise intolerance and weight gain. One month before presentation, the owners noted progressive head swelling and increased respiratory effort and rate. At this time, the referring veterinarian found a significant circumferential indentation of the neck, suggestive of a cicatricial scar. Surgical release was attempted by transecting the scar with four 2-cm incisions perpendicular to the indentation. The swelling and respiratory effort improved only slightly, and the dog was referred to the Veterinary Teaching Hospital.

On presentation, the dog was depressed and obese, with a body condition score of 7/9. A cicatricial indentation was noted around the midcervical region, with crusting and ulceration at several sites along its length. The head, lips, and neck cranial to the scar were markedly swollen. Respiratory rate (40 to 60 breaths per minute), effort, and noise were increased, with occasional stertorous sounds. Although the dog was able to walk, it tired quickly and would lie down after walking short distances. No abnormalities were noted on funduscopic examination. Intraocular pressures in both eyes were 12 mm Hg. Results of a complete blood count (CBC), serum biochemical and electrolyte analyses, and coagulation panel were within normal limits.

Thoracic radiographs were normal, except for obesity. Abnormalities on a single lateral cervical view included a focal ventral indentation of the trachea at the level of the fourth to fifth cervical vertebra (C₄–C₅) and severe soft-tissue swelling extending caudal and ventral to the mandibles and to the level of the third cervical vertebra (C₃) just cranial to a circumferential lucency [Figure 1]. Surgical resection of the scar was recommended.

The dog was premedicated with glycopyrrolate (0.011 mg/kg intramuscularly [IM]), morphine (0.55 mg/kg IM), and acepromazine (0.009 mg/kg IM). Anesthesia was induced with thiopental (11 mg/kg intravenously [IV]) and maintained with isoflurane in oxygen. After the neck was clipped and cleaned, measurements of the neck circumference were 41 cm cranial to the site of constriction, 27 cm at the constriction, and 43 cm caudal to the site of constriction. Cefazolin (22 mg/kg IV) was given at induction and 90 minutes later.

After the site was prepared aseptically, the dog was placed in ventral recumbency, and the dorsal half of the scar was removed. Parallel incisions 2 cm cranial and caudal to the constriction were made. The skin and subcutaneous tissues were dissected toward the center of the scar, which consisted of a band of fibrous tissue that extended into the muscular layers of the neck. The band was attached dorsally to superficial cervical muscles and the nuchal ligament. The abnormal tissue was resected using sharp and blunt dissection. Amultifenestrated, continuous-suction drain was inserted into the wound, exiting through a separate stab incision in the skin caudal to the site. Fascia of the dorsal cervical muscles and subcutaneous tissues were apposed in two layers with 3-0 poliglecaprone 25 in a simple continuous pattern. The skin was apposed with 3-0 nylon in a cruciate pattern.

The dog was repositioned in dorsal recumbency, and, after aseptic preparation, the ventral half of the scar was resected in a similar manner. Lymphatic vessels cranial to the ventral half of the scar were engorged, and in one area these vessels extended through the skin, forming a proliferative soft-tissue mass [Figure 2]. The external jugular veins could not be indentified cranial or caudal to the scar [Figure 3]. Dilated lymphatic vessels were ligated before transection. Sharp dissection was required to transect the scar at midline, where it had adhered to the trachea. A second continuous- suction drain was placed, and the surgical site was closed as described above.

Recovery from anesthesia was uneventful. Postoperative pain was initially managed by administration of hydromorphone (0.1 mg/kg) and acepromazine (0.02 mg/kg) at extubation, followed by a constant-rate IV infusion of morphine (0.2 mg/kg per hour), lidocaine (46 μg/kg per hour), and ketamine (0.2 mg/kg per hour) for the first 18 hours. The dog was then given tramadol (3.8 mg/kg per os [PO] q 8 hours) and hydromorphone (0.1 mg/kg IV once, 30 hours after surgery). Cefazolin (22 mg/kg IV q 8 hours) was administered for the next 36 hours.

Continuous-suction drains were removed 16 hours after surgery, because fluid accumulation was minimal. Head swelling increased slightly 1 day after surgery, and the dog produced occasional stertorous sounds; however, exercise intolerance had resolved. The dog was released 48 hours after surgery. Tramadol (3.8 mg/kg PO q 8 hours) and deracoxib (0.9 mg/kg PO q 24 hours) were administered for 5 days, and amoxicillin/clavulanic acid (18 mg/kg PO q 12 hours) was given for 2 weeks.

Histologically, the excised tissue consisted of severe, chronic, regionally extensive fibrosis, fibroplasia, and neovascularization with multifocal epidermal ulceration, edema, mild lymphoplasmacytic dermatitis, and focal eosinophilic dermatitis with collagenolysis. A remarkable amount of proliferative granulation tissue, with active inflammation and proliferation of fibrovascular tissue, was noted on several sections. Also seen within the sections were naked hairs, which could have incited continued inflammation. No signs of lymphangioma were seen.

Skin sutures were removed 2 weeks after surgery by the referring veterinarian. Swelling had decreased substantially, and activity levels had increased. Two months after surgery, the owners reported that the swelling and clinical signs had resolved completely and that the dog’s activity level was normal. Twenty-seven months after surgery, the owners reported normal activity, appetite, and no palpable scars.

Discussion

Although anecdotal reports are not uncommon, documented reports of constricting circumferential cervical foreign bodies are rare. To the authors’ knowledge, only two cases have been reported in the veterinary literature.^1,2 In one report, a 3- month-old, male domestic shorthaired kitten was presented for respiratory distress and inappetence. The kitten had a rubber band embedded within the soft tissues of the neck, causing tracheal compression.¹ In the second report, a 4-year-old female cockatoo with a 2-week history of regurgitation and cranial cervical swelling had a string embedded within the skin of the neck.² In both animals, the circumferential foreign body was surgically removed, and clinical signs subsequently resolved completely.^1,2

Other differential diagnoses for head and neck swelling include angioedema, rattlesnake bite, subcutaneous emphysema, acute blunt trauma, lymphangiosarcoma of the head and neck, myxedema, salivary mucocele, jugular thrombosis or mass, cellulitis, and abscessation.^3–5 Cranial vena cava syndrome, caused by intrathoracic occlusion of the cranial vena cava, should be considered when the head, neck, and forelimbs display pitting edema. Cranial vena cava syndrome can be caused by thrombosis of the cranial vena cava or by impingement of the vessel by neoplastic or granulomatous masses.^6–8 Cranial vena cava syndrome secondary to a thymoma and a blastomycosis granuloma has also been reported in dogs.^7,8 Dogs with hypoalbuminemia, vasculitis, and right-sided congestive heart failure may be presented with head and neck swelling; however, swelling is rarely restricted to the head and cranial neck unless cervical compression (e.g., a circumferential neck bandage) is present.⁸

A thorough history and physical examination should be performed in animals with acute head swelling to exclude recent blunt trauma or reactions to drugs (e.g., vaccines), insects, or snake venom. A CBC, serum biochemical analysis, coagulation panel, and thoracic radiographs should also be obtained. Further diagnostics, such as skin biopsies or fine-needle aspirates, may be needed to obtain a diagnosis in cases of neoplastic or inflammatory processes (e.g., lymphangiosarcoma, cellulitis).

Treatment of head swelling is aimed at removing the underlying cause.Antihistamines can help decrease the clinical signs associated with hypersensitivity reactions. In severe cases that do not respond to antihistamines, corticosteroids and epinephrine may be necessary. In this dog, surgical resection of the scar most likely reduced compression of the lymphatics, which resulted in improved drainage from the region.

In the dog of this report, head swelling and dyspnea did not develop until 2.5 years after the rubber band had been removed. The occurrence of clinical signs may have been delayed because of continued inflammation or further lymphatic compression. Continued inflammation was noted on histological examination of the resected tissue, possibly because of embedded foreign material (hairs).⁹ In turn, this may have induced further fibroplasia and wound contraction. Additionally, weight gain could have contributed to the late onset of clinical signs because of increased compression of the trachea and lymphatics around the scar.

In dogs, lymphatic drainage of the head and cranial neck is through the right and left tracheal lymphatic trunks, which arise from the retropharyngeal lymph nodes. These lymphatic vessels extend down the neck in, or next to, the carotid sheath. The left tracheal trunk terminates in the thoracic duct, and the right tracheal trunk empties into the angle formed by the right external jugular and right subclavian veins.¹⁰ Although removal of the cicatricial fibrous band in the dog of this report resolved compression of the trachea and cervical soft tissues, vascular and lymphatic drainage of the head and neck were not reestablished surgically. Nevertheless, all clinical signs resolved 2 months after surgery, most likely because new lymphatic drainage routes became established. Experimentally, alternate lymphatic and venous pathways form within 30 days after surgical obstruction of major vessels.³ Techniques for documenting lymphatic drainage include contrast radiography, computed tomography, and magnetic resonance imaging.^11–13 Location of lymphatic and venous drainage was not documented in this dog before or after surgery.

Even though the dog’s owners reported normal activity 27 months after the surgery, potential complications could include recurrence of head swelling from the linear encircling cervical scar formed after surgical resection, particularly if further contracture or weight gain occurs. Use of reconstructive techniques such as Z-plasty could be considered to lengthen the skin along the excision site.¹⁴ However, resolution of the foreign body reaction secondary to embedded hairs and transection of the restrictive fibrous attachments to the underlying muscles and nuchal ligament in this dog may be sufficient to resolve clinical signs.

Conclusion

Although no evidence of rubber band or string remnants was noted within the sections of tissue removed from this dog, histological signs of ongoing inflammation were seen. Hairs within the tissue sections and lack of proper wound care after the rubber band and string were initially removed may have contributed to continued formation of fibrous tissue. To ensure complete healing, thorough examination and appropriate wound care should be performed after foreign bodies (such as string or rubber bands) are removed.