Pulmonary Adenocarcinoma in Dogs: Surgical Treatment with Real-Time Video-Thermometry

Abstract

Background: Pulmonary neoplasia is an abnormal proliferation of cells at the lung tissue, and may be classified as primary, secondary or metastatic, and multisystemic. However, primary neoplasia is rare in canids. Additionally, neoplasms may be classified according to their biological behavior as either malignant or benign. Malignant tumors are more prevalent. The diagnosis can be difficult due to nonspecific symptoms, taking into account that some affected patients do not have symptoms at all; thus, the real incidence of the disease might remain undiagnosed on certain occasions. Therefore, we aimed to report an unprecedented successful case of lung lobectomy surgery in dogs with the aid of infrared video thermometry, which showed real-time images during the surgical procedure. Case: A 10-year-old male dog, crossbreed with Cocker Spaniel, was attended with a history of lethargy, dullness, progressive weight loss, cough, and difficulty breathing. Due to the chronic severity of the clinical signs and the normal physiological clinical examination, complementary exams were requested, such as radiography of the cervical and thoracic regions, cranial and thoracoabdominal computed tomography (TCT). The results of the exams showed the presence of a nodule mass in the right caudal pulmonary lobe which caused a lateral deviation to the left hemithorax of the cardiac silhouette. The patient underwent a surgical procedure with an approach through the thoracic region, at the height of the seventh intercostal space, and a total lobectomy was performed. Throughout the surgical procedure, video thermometry in real-time through the MART station (Metabolic Activity in Real-Time FLIR SC325®) was used to determine the viability of adjacent tissues through temperature differences measured in degrees Celsius. The surgical fragment containing the direct caudal pulmonary lobe and the mass were sent to the pathology sector for anatomopathological evaluation. An abundant papillary epithelial proliferation was visualized through microscopy, presenting areas of necrosis and inflammatory polymorphonuclear infiltrate. The nodule was diagnosed as lung papillary adenocarcinoma. Discussion: Adenocarcinomas consist of papillary, acinar, solid, or mixed glandular structures. They may originate from the airways, bronchial glands, or bronchoalveolar region, and often show invasive growth presenting a rudimentary and irregular shape. The clinical signs are non-specific, including exercise intolerance, non-productive cough, chronic respiratory signs such as tachypnoea or dyspnea, reduced appetite, weight loss, lethargy, chest palpation pain, hemothorax, pneumothorax, and pleural effusion. The diagnosis is concluded through imaging diagnostic tests, of which chest radiography is the most important, followed by magnetic resonance and computed tomography. Also, histopathological examination is essential to determine a definitive diagnosis. The treatment of choice for adenocarcinoma nodules is a surgical excision of the tumor mass. However, the type of surgical approach is determined by different factors such as size, location, and involvement of adjacent structures. The ablation of pulmonary masses may be performed either via partial or total lobectomies. Nevertheless, partial lobectomy is more often performed on non-neoplastic masses or to obtain material for biopsy, whilst total lobectomy is recommended for a malignant neoplasm removal. The prognosis is always guarded, having a more favorable outcome in masses of the smaller diameter without the involvement of adjacent structures.