兽研1. 引言
犬和猫原发性气管肿瘤的发病率尚未确定，但被认为非常低，人类也是如此，据报道人类发病率为每10万人0.142–0.27例[1,2]。已报道的气管肿瘤包括腺癌、癌、髓外浆细胞瘤、平滑肌瘤、纤维肉瘤、肥大细胞瘤、横纹肌肉瘤和鳞状细胞癌[3,4,5,6,7,8]。然而，大多数报道的气管肿瘤为恶性[9,10]。
无论其组织学类型或生物学行为如何，临床症状和影像学表现通常相似。这些肿瘤往往引起气道阻塞[11]，导致非特异性临床症状，包括咳嗽、呼吸困难、血染痰、支气管炎和失声[12,13]。影像学上，它们通常表现为孤立的、边界清晰的气管内肿块[5]。
气管肿瘤通常报道于中年或老年动物，尽管已有报道在2岁以下的犬中描述良性骨软骨瘤和骨软骨发育不良[14,15]。
尽管在人类和兽医学中仅报道了孤立病例，但气管平滑肌瘤在男性中的报道频率高于女性[16]。
鉴于气管肿块可能导致严重、潜在危及生命的气道阻塞，需要及时干预，计算机断层扫描（CT）和支气管镜检查是有价值的补充诊断手段，可用于准确描述病变的位置和范围、评估管腔内受累和腔外延伸、获取组织样本、指导手术规划以及支持预后评估[14,17,18]。根据肿瘤的附着部位，可考虑替代方法，如使用息肉切除圈套器或激光治疗进行内镜下切除[19]。即使未达到完整的手术切缘，气管切除和吻合术也可能比内镜下减瘤术提供更长的无病间期[20]。
2. 病例描述
2.1. 临床表现
一只12岁已绝育雌性比特犬，体重27 kg，因慢性呼吸系统症状就诊，包括咳嗽、打喷嚏、发绀和呼吸急促，其特征为冬季月份季节性加重，并在前一个月内进行性恶化。该犬因符合严重上气道阻塞的体征（包括吸气性呼吸困难、呼吸急促和发绀发作）而作为急诊收治。上气道检查发现双侧喉麻痹（LP），并进行了左侧杓状软骨外侧化术。血液学和血清生化结果，包括血清总甲状腺素浓度，均在各自的参考区间内。尽管接受了手术治疗，该犬仍持续表现出需要经口气管插管的呼吸阻塞体征。随后进行了急诊支气管镜检查，发现一个气管内肿块导致约90%的气道管腔阻塞。由于阻塞的严重性和确保气道的需要，在肿块尾侧进行了临时气管造口术。
2.2. 影像学诊断
进行了平扫和增强CT检查，以规划肿瘤切除并评估是否存在额外肿块或转移性疾病。CT显示一个气管肿块从第9至第15气管环延伸，占据约90%的气管管腔。平扫CT上，肿块的平均衰减值为33 HU，符合软组织病变。尽管先前左侧杓状软骨外侧化术后声门开口充分，但仍观察到持续性气道阻塞。肿块似乎起源于背侧气管韧带，并在C3–C4椎体水平引起食管压迫（图1）。未检测到转移性疾病的证据。
胸部和颈部X线片未显示气管内肿块的证据，可能是由于其影像学显眼度低以及邻近软组织结构的重叠。
2.3. 手术和麻醉管理
将犬置于仰卧位，颈部伸展。从环状软骨尾侧缘做腹侧中线皮肤切口，向尾侧延伸约12 cm，包括临时气管造口部位。沿中线缝将成对的胸骨甲状肌分开，暴露气管。肿块位于气管右背外侧，并延伸入气管管腔。双侧识别并仔细分离颈动脉鞘和喉返神经。在环状软骨尾侧20 mm处和气管造口部位尾侧一个气管环处横断气管。共切除10个气管环，相当于气管总长度的24%。获得了10 mm的头侧和尾侧手术切缘（图2）。
气管吻合采用2-0尼龙支撑缝合线。首先在气管背侧韧带放置三根缝线，随后围绕气管周径分布放置额外的间断缝线，每根缝线均穿过切除部位头侧一个软骨环和尾侧一个软骨环。所有缝线放置完毕后，依次打结以完成端端吻合[21]。其余组织层按常规使用3-0 Monosyn闭合（图3）。
麻醉最初采用丙泊酚全静脉麻醉维持，经气管造口部位行气管插管。端端气管吻合开始后，改为经口气管插管，并将维持方式转为部分静脉麻醉，即100%氧气输送异氟烷联合右美托咪定持续速率输注（表1）。
2.4. 组织学检查结果
手术标本为一段包含10个气管环的气管节段及一个边界清晰、质地坚实、肉样肿块，直径3 cm。肿块压迫气管并导致气管腔明显狭窄（图2c）。标本置于福尔马林中送检进行组织病理学检查。
组织病理学检查显示肿瘤起源于气管平滑肌。肿瘤无侵袭性、无包膜、边界清晰。肿瘤细胞呈致密束状排列，束间由少量结缔组织分隔，细胞质边界不清。细胞核呈长形、两端钝圆，呈特征性雪茄状外观。所检切片中未见核分裂象。最终诊断为气管平滑肌瘤（图4）。未进行免疫组化染色以确认平滑肌分化。
2.5. 转归
犬恢复顺利，无并发症。术后管理包括以维持速率输注乳酸林格氏液进行液体治疗，以及多模式镇痛，即美沙酮（0.1 mg/kg，每4 h一次）联合安乃近（10 mg/kg，每12 h一次）。根据格拉斯哥复合疼痛量表系列疼痛评估结果，逐步递减镇痛。
阿莫西林-克拉维酸（20 mg/kg，每12 h一次）作为围手术期抗菌预防给药。其他静脉用药包括马罗匹坦止吐（1 mg/kg，每24 h一次）和地塞米松抗炎（0.1 mg/kg，每24 h一次）。
住院期间手术部位保持清洁干燥。犬于术后48 h出院，无呼吸系统症状。术后15天复查时，除兴奋或紧张时偶有轻度咳嗽外，犬无呼吸异常。随后通过电话进行随访，主人报告临床转归良好。撰写本文时，即接受端端气管吻合术后两年，该犬仍无呼吸系统症状。主人报告其活动水平明显增加，能够奔跑和玩耍，无呼吸困难或咳嗽。
3. 讨论
原发性气管肿瘤在兽医和人医中均不常见[23,24]。在人类中，气管平滑肌瘤约占所有已报告气管肿瘤的1%，而已报告的气管肿瘤中90%以上为恶性[16,25,26]。在犬中，气管肿瘤可分为软骨性和非软骨性，后者更常见；气管平滑肌瘤属于此组[27]。
与既往报告一致，气管肿瘤最常位于气管颈段，通常发生于中年至老年犬[13]，本病例犬确诊时12岁，病变位于C3–C4椎体水平。
关于气管平滑肌瘤的现有文献有限。在人类医学中，原发性气管平滑肌瘤似乎更常见于男性，而肺实质平滑肌瘤则更多见于女性。在此背景下，呼吸道平滑肌病变应与良性转移性平滑肌瘤相鉴别，后者是一种罕见病变，主要见于有子宫平滑肌瘤病史或既往子宫手术史的女性。因此，评估生殖史和手术史具有相关性[28]。在本病例中，该犬为已绝育雌性，无已知子宫平滑肌瘤病史。此外，进行了CT以排除其他肿块的存在，未发现其他病变或转移性疾病证据。这些发现连同病变的孤立性，支持肿瘤原发于气管。
此类肿瘤的主要风险不一定在于恶性生物学行为，而在于其引起功能性气道阻塞的能力，可能严重损害通气[11,28]。在本病例中，临床症状逐渐进展，并出现急性加重，需要临时气管造口以稳定犬的状况并允许规划确定性手术治疗。
临床表现无特异性，与既往报道一致，包括与上气道梗阻相符的呼吸异常，如吸气性呼吸困难、呼吸急促、发绀发作及声音嘶哑[13,28,29]。尽管CT上观察到食管受压，但该犬未表现出吞咽困难。平扫CT上，肿块平均衰减为33亨氏单位（HU），与软组织衰减一致。该值处于人类气管支气管平滑肌瘤的报道范围（25–46 HU）内。尽管这些肿瘤通常在造影后表现为均匀强化，但本病例中病灶仅显示轻微强化，其平均衰减从33仅增至34 HU[30]。
尽管气管腔内肿块在X线片上可被识别为边界清晰的病变[5]，但在本病例中，胸部和颈部X线片未显示与气管肿瘤相符的征象。直至因左侧杓状软骨外侧化术后呼吸症状加重而实施紧急支气管镜检查时，才诊断出腔内肿块。这一发现强调了对于持续性梗阻症状的犬，即使影像学检查未见明显异常，也应考虑气管腔内病变的重要性。
从解剖和外科角度来看，气管是下呼吸道的一部分，在哺乳动物中由一系列C形透明软骨环组成，软骨环之间由环状韧带连接，背侧由气管肌连接[31]。犬的气管约包含35–46个气管环（cartilagines tracheales）[32]。尽管关于犬可安全切除的气管最大长度尚无明确共识，但一些研究提示可切除成人气管长度的50%[33]。然而，据报道切除约30%的气管长度与肺的前移相关[34]。在人类医学中，超过50%气管长度的切除通常需要端端吻合以外的重建技术，因为吻合线处会产生张力[35]。相反，绵羊研究表明可切除高达58%的气管而不发生并发症[36]。
本病例采用的手术技术为气管节段性切除加端端吻合，与既往兽医外科文献描述一致[21]。在本犬中，切除部分占气管总长度的24%。无需更广泛的切除，因为头侧和尾侧均获得了10 mm的充分宏观手术切缘。该百分比处于文献认为安全的范围内，这可能有助于降低与吻合口张力相关的并发症风险[37]。因此，术后无需保持颈部屈曲位，也无需使用术后减张缝线，如颏胸缝线。采用2-0不可吸收单丝缝线（尼龙）构建吻合。然而，科学文献中更常描述使用更细的可吸收单丝缝线材料[21,34]。
关于手术切缘，犬气管肿瘤的具体证据有限。然而，在某些恶性气管肿瘤（如鳞状细胞癌）中，大于5 mm的切缘已被描述为足够[20]。在本病例中，由于肿瘤为平滑肌瘤且实现了完全切除，预后被认为良好[38]。临床结局支持这一点，该犬在两年随访期内无呼吸道症状且无复发证据。由于附着基底部宽且病变范围大，支气管镜引导下内镜切除被认为不合适。
尽管气管切除吻合的手术技术在兽医领域已有充分描述，但这些操作中麻醉管理的现有信息仍然有限[39,40,41]。在本病例中，该犬不需要逆行插管或使用声门上气道装置。最初，通过先前放置的临时气管造口进行通气，这在操作初期提供了安全的气道控制。一旦开始端端吻合，即改为经口气管插管，从而在不显著干扰术野的情况下完成气管重建。
在人类医学中，尽管在专科中心进行气管切除重建术的死亡率较低，约为1-2%，但并发症发生率可达18.2%[42]。在本病例中，气管切除及端端吻合术后，该犬未出现术后并发症。无需放置颈部保护性缝线来限制颈部伸展并减少吻合口张力。同样，也未观察到相关麻醉并发症，如低氧血症发作，此前一些小动物气管手术麻醉管理的报告中曾描述过此类情况[39]。关于喉麻痹（LP），最常报告的病因是特发性的，但也有获得性病因的描述，如咬伤创伤或纵隔肿块[43]。较少见的病因包括周围肌肉矿化[44]和肌肉假性肿瘤[45]。在本病例中，怀疑LP继发于气管肿瘤与喉返神经的粘连，尽管无法确认明确的因果关系。杓状软骨侧向化术有助于气管肿块切除后气流的改善。入院时注意到的吠声音调轻度改变归因于LP[43]，并在长期随访中持续存在。术后其持续存在可能与左侧杓状软骨侧向化术有关，因为将杓状软骨维持在外展位置可能影响声带张力和振动。在粘连肿块分离过程中对迷走神经或其喉返分支的操作也可能有所贡献。虽然不能排除节段性气管切除后气道共振的改变，但这被认为是可能性较小的解释。因此，吠声音调的改变无法确定地归因于单一原因。
总体而言，本病例强调了在持续性阻塞性气道症状的犬的鉴别诊断中纳入气管腔内肿瘤的重要性，即使影像学发现为非特异性的。支气管镜检查和CT对诊断和手术规划至关重要。节段性气管切除联合端端吻合术实现了病变的完全切除，临床结局良好，无相关围手术期并发症。
4. 结论
气管平滑肌瘤在兽医和人类医学中均为罕见肿瘤。尽管由于功能性气道阻塞可能引起明显的呼吸症状，但肿块的完全手术切除可能具有治愈性。然而，这些病变的管理需要外科和麻醉团队之间的密切协调，特别是确保整个手术过程中充分的气道控制。
撰写本文时，距手术已过去两年，呼吸症状无复发。主人仅报告吠声音调轻度改变，与临床症状出现时注意到的相似。
本病例强调了多学科方法对罕见或复杂疾病（如气管平滑肌瘤）的重要性，并表明适当的诊断、手术和麻醉规划可带来良好的长期临床结局。
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1. Introduction
The incidence of primary tracheal neoplasms in dogs and cats has not been established, but it is considered to be very low, as is also the case in humans, in whom an incidence of 0.142–0.27 cases per 100,000 people has been reported [1,2]. Reported tracheal neoplasms include adenocarcinoma, carcinoma, extramedullary plasmacytoma, leiomyoma, fibrosarcoma, mast cell tumour, rhabdomyosarcoma, and squamous cell carcinoma [3,4,5,6,7,8]. However, most reported tracheal tumours are malignant [9,10].
Regardless of their histological type or biological behaviour, the clinical signs and radiographic findings are usually similar. These tumours tend to cause airway obstruction [11], resulting in non-specific clinical signs, including coughing, dyspnoea, blood-tinged sputum, bronchitis, and aphonia [12,13]. Radiographically, they usually appear as solitary, well-defined intratracheal masses [5].
Tracheal neoplasms are usually reported in middle-aged or older animals, although benign osteochondroma and osteochondral dysplasia have been described in dogs younger than 2 years of age [14,15].
Although only isolated cases have been reported in both human and veterinary medicine, tracheal leiomyomas have been reported more frequently in men than in women [16].
Given the potential for tracheal masses to cause severe, potentially life-threatening airway obstruction requiring prompt intervention, computed tomography (CT) and bronchoscopy are valuable complementary diagnostic modalities for accurately characterising the location and extent of the lesion, assessing luminal involvement and extraluminal extension, obtaining tissue samples, guiding surgical planning, and supporting prognostic assessment [14,17,18]. Depending on the attachment site of the tumour, alternative approaches such as endoscopic resection using a polypectomy snare or laser therapy may be considered [19]. Tracheal resection and anastomosis may provide a longer disease-free interval than endoscopic debulking, even when complete surgical margins are not achieved [20].
2. Case Description
2.1. Clinical Presentation
A 12-year-old spayed female Pit Bull weighing 27 kg was presented with a history of chronic respiratory signs, including coughing, sneezing, cyanosis, and tachypnoea, characterised by seasonal worsening during the winter months and progressive deterioration over the preceding month. The dog was admitted as an emergency because of signs compatible with severe upper airway obstruction, including inspiratory dyspnoea, tachypnoea, and cyanotic episodes. Examination of the upper airway revealed bilateral laryngeal paralysis (LP), and left arytenoid lateralisation was performed. Haematological and serum biochemical results, including the serum total thyroxine concentration, were within their respective reference intervals. Despite surgical treatment, the dog continued to show signs of respiratory obstruction requiring orotracheal intubation. Emergency bronchoscopy was subsequently performed and revealed an intraluminal tracheal mass causing approximately 90% obstruction of the airway lumen. Because of the severity of the obstruction and the need to secure the airway, a temporary tracheostomy was performed caudal to the mass.
2.2. Imaging Diagnosis
An unenhanced and contrast-enhanced CT examination was performed to plan tumour resection and to assess the presence of additional masses or metastatic disease. CT revealed a tracheal mass extending from the ninth to the 15th tracheal ring and occupying approximately 90% of the tracheal lumen. On unenhanced CT, the mass showed a mean attenuation value of 33 HU, consistent with a soft-tissue lesion. Persistent airway obstruction was observed despite adequate glottic opening following the previous left arytenoid lateralisation. The mass appeared to arise from the dorsal tracheal ligament and caused oesophageal compression at the level of the C3–C4 vertebral bodies (Figure 1). No evidence of metastatic disease was detected.
Thoracic and cervical radiographs did not reveal evidence of the intraluminal tracheal mass, probably because of its low radiographic conspicuity and superimposition of adjacent soft-tissue structures.
2.3. Surgical and Anaesthetic Management
The dog was positioned in dorsal recumbency with the neck extended. A ventral midline skin incision was made from the caudal border of the cricoid cartilage and extended approximately 12 cm caudally, incorporating the temporary tracheostomy site. The paired sternothyroid muscles were separated along the midline raphe, and the trachea was exposed. The mass was located on the right dorsolateral aspect of the trachea and extended into the tracheal lumen. The carotid sheaths and recurrent laryngeal nerves were identified and carefully dissected bilaterally. The trachea was transected 20 mm caudal to the cricoid cartilage and one tracheal ring caudal to the tracheostomy site. A total of 10 tracheal rings were removed, corresponding to 24% of the total tracheal length. Cranial and caudal surgical margins of 10 mm were obtained (Figure 2).
For the tracheal anastomosis, 2-0 nylon stay sutures were used. Three sutures were initially placed in the dorsal tracheal ligament, followed by additional interrupted sutures distributed circumferentially around the trachea, each engaging one cartilage ring cranial and one cartilage ring caudal to the resection site. Once all sutures had been placed, they were sequentially tied to complete the end-to-end anastomosis [21]. The remaining tissue layers were closed routinely using 3-0 Monosyn (Figure 3).
Anaesthesia was initially maintained using total intravenous anaesthesia with propofol, with the trachea intubated via the tracheostomy site. Once the end-to-end tracheal anastomosis was initiated, orotracheal intubation was performed, and maintenance was transitioned to partial intravenous anaesthesia, consisting of isoflurane delivered in 100% oxygen combined with a continuous rate infusion of dexmedetomidine (Table 1).
2.4. Histological Findings
The surgical specimen consisted of a tracheal segment containing 10 tracheal rings and a well-demarcated, firm, fleshy mass measuring 3 cm in diameter. The mass compressed the trachea and caused marked narrowing of the tracheal lumen (Figure 2c). The specimen was placed in formalin and submitted for histopathological examination.
Histopathological examination showed that the neoplasm arose from the tracheal smooth muscle. It was non-invasive, unencapsulated, and well-demarcated. The neoplastic cells were arranged in dense bundles separated by scant connective tissue and had indistinct cytoplasmic borders. The nuclei were elongated with rounded ends, giving them the characteristic cigar-shaped appearance. No mitotic figures were identified in the sections examined. The final diagnosis was tracheal leiomyoma (Figure 4). Immunohistochemical staining was not performed to confirm smooth muscle differentiation.
2.5. Outcome
The dog recovered without complications. Postoperative management included fluid therapy with lactated Ringer’s solution at a maintenance rate, together with multimodal analgesia consisting of methadone (0.1 mg/kg every 4 h) combined with metamizole (10 mg/kg every 12 h). Analgesia was progressively tapered according to serial pain assessments using the Glasgow Composite Measure Pain Scale.
Amoxicillin–clavulanic acid (20 mg/kg every 12 h) was administered as perioperative antimicrobial prophylaxis. Additional intravenous medications included maropitant as an antiemetic (1 mg/kg every 24 h) and dexamethasone for anti-inflammatory treatment (0.1 mg/kg every 24 h).
The surgical site was kept clean and dry throughout the hospitalisation period. The dog was discharged 48 h after surgery with no respiratory signs. At the follow-up examination 15 days after surgery, the dog showed no respiratory abnormalities, except for occasional mild coughing episodes when excited or nervous. Further follow-up was conducted by telephone, during which the owners reported a favourable clinical outcome. At the time of writing, two years after undergoing end-to-end tracheal anastomosis, the dog remains free of respiratory signs. The owners reported that her activity level had markedly increased and that she was able to run and play without respiratory distress or coughing.
3. Discussion
Primary tracheal neoplasms are uncommon in both veterinary and human medicine [23,24]. In humans, tracheal leiomyomas account for approximately 1% of all reported tracheal neoplasms, and more than 90% of reported tracheal tumours are malignant [16,25,26]. In dogs, tracheal neoplasms can be classified as cartilaginous or non-cartilaginous, with the latter being more frequent; tracheal leiomyoma is included within this group [27].
Consistent with previous reports, in which tracheal neoplasms are most commonly located in the cervical portion of the trachea and usually occur in middle-aged to geriatric dogs [13], the dog in the present case was diagnosed at 12 years of age, and the lesion was located at the level of the C3–C4 vertebral bodies.
The available literature on tracheal leiomyomas is limited. In human medicine, primary tracheal leiomyomas appear to occur more frequently in men, whereas pulmonary parenchymal leiomyomas have been reported more commonly in women. In this context, leiomyomatous lesions of the respiratory tract should be differentiated from benign metastasising leiomyoma, a rare entity described mainly in women with a history of uterine leiomyoma or previous uterine surgery. Therefore, assessment of reproductive and surgical history is relevant [28]. In the present case, the dog was a spayed female with no known history of uterine leiomyoma. In addition, CT was performed to rule out the presence of other masses, and no additional lesions or evidence of metastatic disease were identified. These findings, together with the solitary nature of the lesion, supported a primary tracheal origin of the neoplasm.
The main risk associated with this type of neoplasm does not necessarily lie in malignant biological behaviour, but rather in its ability to cause functional airway obstruction, which may severely compromise ventilation [11,28]. In this case, the clinical signs progressed gradually, with acute worsening that required temporary tracheostomy to stabilise the dog and allow planning of definitive surgical treatment.
The clinical signs were non-specific, as previously reported, and included respiratory abnormalities compatible with upper airway obstruction, such as inspiratory dyspnoea, tachypnoea, cyanotic episodes, and hoarseness [13,28,29]. Although oesophageal compression was observed on CT, the dog did not show dysphagia. On unenhanced CT, the mass showed a mean attenuation of 33 Hounsfield units (HU), consistent with soft-tissue attenuation. This value falls within the range reported for human tracheobronchial leiomyomas (25–46 HU). Although these tumours typically show homogeneous enhancement following contrast administration, the lesion in the present case showed minimal enhancement, with its mean attenuation increasing from 33 to only 34 HU [30].
Although intraluminal tracheal masses may be radiographically identified as well-defined lesions [5], in this case, thoracic and cervical radiographs did not reveal findings compatible with tracheal neoplasia. The intraluminal mass was not diagnosed until emergency bronchoscopy was performed because of worsening respiratory signs after left arytenoid lateralisation. This finding highlights the importance of considering intraluminal tracheal lesions in dogs with persistent obstructive signs, even when radiographic examination does not show evident abnormalities.
From an anatomical and surgical perspective, the trachea is part of the lower respiratory tract and, in mammals, consists of a sequence of C-shaped hyaline cartilage rings connected by annular ligaments and joined dorsally by the trachealis muscle [31]. In dogs, the trachea comprises approximately 35–46 tracheal rings (cartilagines tracheales) [32]. Although there is no definitive consensus regarding the maximum length of the trachea that can be safely resected in dogs, some studies suggest that up to 50% of the adult tracheal length may be removed [33]. However, resection of approximately 30% of the tracheal length has been reported to be associated with cranial displacement of the lungs [34]. In human medicine, resections exceeding 50% of the tracheal length usually require reconstructive techniques other than end-to-end anastomosis because of the tension generated at the suture line [35]. Conversely, studies in sheep have shown that up to 58% of the trachea can be resected without the development of complications [36].
The surgical technique used in this case was segmental tracheal resection with end-to-end anastomosis, as previously described in the veterinary surgical literature [21]. In the present dog, the resection represented 24% of the total tracheal length. A more extensive resection was not required, as adequate macroscopic surgical margins of 10 mm were obtained both cranially and caudally. This percentage is within the limits considered safe in the literature, which probably contributed to reducing the risk of complications associated with anastomotic tension [37]. Accordingly, it was not necessary to maintain the neck in flexion during the postoperative period or to use postoperative tension-relieving sutures, such as chin-to-chest sutures. A 2-0 non-absorbable monofilament suture (nylon) was used to construct the anastomosis. However, finer absorbable monofilament suture material is more commonly described in the scientific literature [21,34].
Regarding surgical margins, specific evidence for canine tracheal tumours is limited. However, in some malignant tracheal neoplasms, such as squamous cell carcinoma, margins greater than 5 mm have been described as sufficient [20]. In this case, because the tumour was a leiomyoma and complete resection was achieved, the prognosis was considered favourable [38]. This was supported by the clinical outcome, as the dog remained free of respiratory signs and showed no evidence of recurrence during a two-year follow-up period. Owing to the broad base of attachment and the extent of the lesion, endoscopic excision under bronchoscopic guidance was not considered appropriate.
Although the surgical technique of tracheal resection and anastomosis is well-described in veterinary medicine, the available information on anaesthetic management during these procedures remains limited [39,40,41]. In the present case, the dog did not require retrograde intubation or the use of a supraglottic airway device. Initially, ventilation was performed through the previously placed temporary tracheostomy, which allowed safe airway control during the initial phase of the procedure. Once the end-to-end anastomosis had been initiated, the dog was intubated orotracheally, allowing completion of the tracheal reconstruction without significant interference with the surgical field.
In human medicine, although mortality associated with tracheal resection and reconstruction in specialised centres is low, approximately 1–2%, the complication rate may reach 18.2% [42]. In the present case, after tracheal resection and end-to-end anastomosis, the dog did not develop postoperative complications. Placement of a cervical guardian suture to limit neck extension and reduce tension on the anastomosis was not required. Likewise, no relevant anaesthetic complications, such as episodes of hypoxaemia, which have previously been described in some reports of anaesthetic management of tracheal surgery in small animals, were observed [39]. Regarding LP, the most commonly reported cause is idiopathic, although acquired causes such as bite trauma or mediastinal masses have also been described [43]. Less frequent causes include mineralisation of the surrounding muscles [44] and muscular pseudotumours [45]. In the present case, LP was suspected to be secondary to adhesion of the tracheal tumour to the recurrent laryngeal nerve, although a definitive causal relationship could not be confirmed. Arytenoid lateralisation contributed to improved airflow following removal of the tracheal mass. The mild change in bark tone noted at admission was attributed to LP [43] and persisted throughout long-term follow-up. Its persistence after surgery may have been associated with left arytenoid lateralisation, as maintaining the arytenoid cartilage in an abducted position may affect vocal fold tension and vibration. Manipulation of the vagus nerve or its recurrent laryngeal branch during dissection of the adherent mass may also have contributed. Although changes in airway resonance following segmental tracheal resection cannot be ruled out, this was considered a less likely explanation. Consequently, the change in bark tone could not be attributed with certainty to a single cause.
Overall, this case highlights the importance of including intraluminal tracheal neoplasms in the differential diagnosis of dogs with persistent obstructive airway signs, even when radiographic findings are non-specific. Bronchoscopy and CT were essential for diagnosis and surgical planning. Segmental tracheal resection with end-to-end anastomosis allowed complete excision of the lesion, with a favourable clinical outcome and no relevant perioperative complications.
4. Conclusions
Tracheal leiomyomas are rare neoplasms in both veterinary and human medicine. Although they may cause marked respiratory signs due to functional airway obstruction, complete surgical resection of the mass may be curative. However, the management of these lesions requires close coordination between the surgical and anaesthetic teams, particularly to ensure adequate airway control throughout the procedure.
At the time of writing, two years had elapsed since surgery, with no recurrence of respiratory signs. The owners reported only a mild change in the tone of the bark, similar to that noted at the onset of the clinical signs.
This case highlights the importance of a multidisciplinary approach to rare or complex conditions, such as tracheal leiomyoma, and demonstrates that appropriate diagnostic, surgical, and anaesthetic planning can lead to favourable long-term clinical outcomes.