Tracheal narrowing secondary to airway obstruction in two cats

Tracheal narrowing is described in two cats. In both cases, inspiratory radiographs demonstrated tracheal narrowing just cranial to the thoracic inlet; no narrowing was seen on expiratory radiographs. Magnetic resonance imaging revealed suspected nasal tumours in both cases, but no abnormalities were identified in the region of the narrowed trachea. Nasal biopsy confirmed intranasal lymphoma in one cat and nasal adenocarcinoma in the other. The former cat was treated with chemotherapy. The owner of the latter cat declined further treatment. The tracheal narrowing disappeared after the initiation of chemotherapy in the cat with intranasal lymphoma and it is suggested that the narrowing might have been associated with the nasal tumour. A careful evaluation of the airway, especially cranial to the narrowing, is recommended in cases of tracheal narrowing in cats.     

Diagnosis and treatment of tracheal basal cell carcinoma in a Maine coon and long-term outcome

A 6 yr old castrated male Maine coon presented with a 2 wk history of progressive dyspnea. Thoracic radiographs revealed a 2 cm diameter intratracheal mass at the level of the fourth rib. The tracheal mass was marginally excised via a combination of resection and anastomosis. Infiltrative basal cell carcinoma (BCC) with nodular osseous metaplasia was diagnosed. The thoracic trachea was then irradiated postoperatively for definitive treatment. The cat remained asymptomatic following surgical excision and radiation therapy for 32 mo when this report was written. The purpose of this report is to describe the treatment and long-term outcome of a Maine coon diagnosed with, and treated for, tracheal BCC.     

Radiographic measurements of the trachea in domestic shorthair and Persian cats

Tracheal diameter can be assessed from a thoracic radiograph, with assessment of tracheal diameter in dogs based on ratios between tracheal diameter and a skeletal measurement. Reference intervals are not, however, available for the cat. Tracheal narrowing may cause significant clinical problems, although tracheal hypoplasia in dogs may be clinically silent, and is rarely reported in cats (both mesati- and brachycephalic). The tracheal diameter and trachea:thoracic inlet and trachea:rib ratios were calculated for populations of domestic shorthair (DSH) (n?=?68) and Persian (n?=?40) cats. This gave reference intervals for radiographic tracheal measurements in these breeds. It is proposed that the tracheal diameter in a normal DSH cat should be 18% of the diameter of the thoracic inlet, and compared to 20% in Persian cats.     

A quantitative study on the trachea of the dog

This study was carried out to record the detailed morphometric structure of the trachea in dogs using 15 female and four male healthy adult mongrel dogs. The diameter and thickness of each tracheal ring were measured, the number of tracheal rings varying from 36 to 45. All data were subjected to statistical analysis which was carried out on individual sections of the trachea, i.e. the cranial cervical, middle cervical, thoracic inlet and the intrathoracic tracheal regions, which consisted of 12, 12, nine and 12 tracheal rings, respectively. Fusion of the tracheal rings was especially obvious in the cranial cervical and thoracic inlet regions as a result of neck movements. The diameter and thickness of the tracheal rings are smallest at the thoracic inlet level because the direction of the trachea changes at this point where the thoracic inlet is relatively small and surrounded by bone. The ratios of inner transverse to inner vertical and outer transverse to outer vertical diameters were almost the same, between 1.14 and 1.25 in all regions, which indicated that the trachea is near-circular in shape in the dog. At the thoracic inlet level cross-sectional lumen areas are 7 and 6% smaller than those in the middle cervical and intrathoracic regions, respectively. The thinnest cartilage was seen at the thoracic inlet level where there is a risk of tracheal collapse.     

COMPUTED TOMOGRAPHIC,RADIOGRAPHIC, AND ENDOSCOPIC TRACHEAL DIMENSIONS IN ENGLISH BULLDOGS WITH GRADE 1 CLINICAL SIGNS OF BRACHYCEPHALIC AIRWAY SYNDROME

Tracheal hypoplasia is commonly seen in English Bulldogs affected with brachycephalic airway syndrome. Previously published diagnostic criteria for tracheal hypoplasia in this breed have been a radiographic tracheal diameter:tracheal inlet ratio (TD:TI) < 0.12 or a tracheal diameter:third rib diameter ratio (TD:3R) < 2.0. Computed tomography has become increasingly used for airway evaluation, however published information is lacking regarding CT tracheal dimensions in English Bulldogs. Objectives of this prospective cross‐sectional study were to describe radiographic and CT tracheal dimensions in a sample of clinically normal English Bulldogs and compare these values with tracheoscopy scores. Computed tomography (n = 40), radiography (n = 38), and tracheoscopy (n = 40) studies were performed during a single general anesthesia session for each included dog. Tracheal measurements were recorded at three locations: cervical, thoracic inlet, and thorax. Tracheal diameters were narrowest at the thoracic inlet with all techniques. Computed tomographic measurements averaged 19% greater than radiographic measurements. All included dogs had radiographic tracheal measurements greater than the previously published criteria for tracheal hypoplasia. Mean CT TD:TI was 0.26 (± 0.03, 0.20–0.33), and mean CT TT:3R was 2.27 (± 0.24, 1.71–2.74). Radiographic TD:TI and CT TD:TI were significantly correlated (P = 0.00); however radiographic TT:3R and CT TT:3R were not significantly correlated (P = 0.25). Tracheoscopy identified hypoplastic changes in all dogs and tracheoscopy scores were not correlated with CT or radiography diameter measurements. In conclusion, findings indicated that some CT and radiographic tracheal diameter measurements were comparable in English Bulldogs however diameters for both imaging techniques were not comparable with tracheoscopy scores.     

Measurement of tracheal diameters using ultrasonography versus computed tomography in Beagle dogs

ObjectiveTo compare ultrasonography with computed tomography (CT) for assessment of tracheal diameter as a feasibility study for endotracheal tube selection.Study designProspective study.AnimalsA total of nine Beagle dogs with a median (interquartile range) weight of 7.4 (7.2–7.7) kg.MethodsTracheal diameter measurements were obtained at two locations: 1 cm proximal to caudal border of the cricoid cartilage (sublaryngeal; SL) and dorsal to above cranial border of the manubrium (thoracic inlet; TI). For CT, dogs were anesthetized with propofol and sevoflurane, in sternal recumbency, and measurements obtained after controlled ventilation–induced apnea and the endotracheal tube cuff was deflated. Transverse diameter, right and left 45° oblique diameters were measured. For ultrasonography, unsedated dogs were standing with slight neck extension, and images obtained in ventrodorsal, 45° right and left oblique ways after expiration. Diameters between the tracheal lumen mucosal borders were measured. The degree of agreement between the tracheal diameters measured at SL and TI locations with CT (TD_CT-SL and TD_CT-TI) and ultrasonography (TD_US-SL and TD_US-TI) was verified using the Bland-Altman method.ResultsThe agreement between the measurements obtained with CT and ultrasonography was revealed by Bland-Altman analyses, although ultrasonography tended to slightly underestimate the tracheal diameter.Conclusions and clinical relevanceUltrasonography can be applied for tracheal diameter measurement. Although further studies are required, an endotracheal tube selection method, using ultrasonography, could be proposed.     

Multimodality imaging characteristics of tension pyopneumothorax secondary to pulmonary carcinoma in a cat

A 3‐year‐old Himalayan cat was presented with respiratory distress. Radiography showed multiple gas opacity foci, with the locations dependent on patient positioning, and severe pleural effusion with a contralateral mediastinal shift. A large volume of fluid and air was aspirated, and the fluid components were consistent with a nonseptic exudate. A pulmonary mass, pleural nodules, and an air–fluid interface with air bubbles trapped in fibrous septations were identified using thoracic ultrasonography and CT. The cat died 2 days after imaging studies. Necropsy revealed tension pyopneumothorax caused by pulmonary carcinoma and multiple pleural metastases.     

RADIOGRAPHIC QUANTIFICATION OF TRACHEAL DIMENSIONS OF THE NORMAL THOROUGHBRED HORSE

Radiographic measurement of tracheal dimensions in the horse may be useful in evaluating upper and lower respiratory tract conditions due to the gradient of pressure changes between these areas. Lateral radiographs of the trachea of 15 normal sedated Thoroughbred horses were made at inspiration and expiration and magnification-corrected mean airway heights measured were, respectively: larynx: 5.89 and 5.86 cm; trachea at the third cervical vertebra (C3): 4.17 and 4.04 cm; at the fifth cervical vertebra (C5): 3.62 and 3.59 cm; at the first thoracic vertebra (T1): 3.4 and 3.23 cm; and carina: 3.85 and 4.12 cm. The ratio of airway height to nearby vertebral body lengths, at inspiration and expiration were, respectively: laryngeal height at C3: 0.56 and 0.56; tracheal height at C3: 0.4 and 0.39; at C5: 0.37 and 0.37; at T1: 0.59 and 0.59; and carina height: 0.91 and 0.94. The ratio of tracheal height to the thoracic inlet at inspiration and expiration was, respectively, 0.15 and 0.15. There was not a statistically significant association between airway diameter and phase of respiration. No association was found between tracheal height and body mass or height at the withers. Radiographic tracheal height can be measured independent of respiratory phase in sedated horses. It is suggested that the ratio of tracheal height to an adjacent bony landmark is more reliable for comparison between horses and tracheal height measurement should be made at C5, due to a lower standard deviation. If only thoracic radiographs are made, measurements of tracheal height at the thoracic inlet may be valuable.     

Fracture of an endoluminal nitinol stent used in the treatment of tracheal collapse in a dog

A 5-year-old castrated male Pomeranian was evaluated because of severe dyspnea and coughing, and a diagnosis of complete, static collapse of the trachea at the thoracic inlet was made. After failure to improve with medical management alone, an endoluminal tracheal stent was placed, which resulted in resolution of signs. Ten weeks after stent placement, the dog underwent tracheal resection and anastomosis because the stent had fractured at the level of the thoracic inlet. One year after surgery, the dog was doing well and required treatment with hydrocodone infrequently. Compared with other surgical treatment options, placement of an endoluminal tracheal stent is a relatively noninvasive intervention that can provide effective relief from the clinical signs associated with tracheal collapse in dogs. Implantation of endoluminal tracheal stents may be associated with complications; therefore, the procedure may best be regarded as a salvage procedure for dogs with end-stage disease that are refractory to appropriate medical management, have extensive collapse of the intrathoracic portion of the trachea, or are poor candidates for surgery.     

Fluoroscopic and radiographic evaluation of tracheal collapse in dogs: 62 cases (2001-2006)

OBJECTIVE: To compare the use of radiography and fluoroscopy for detection and grading of tracheal collapse in dogs. DESIGN: Retrospective case series. Animals-62 dogs with tracheal collapse. PROCEDURES: For each dog, tracheal collapse was confirmed fluoroscopically and lateral cervical and thoracic radiographic views were reviewed. A board-certified radiologist (who was unaware of the dogs' clinical history) evaluated the cervical, thoracic inlet, thoracic, carinal, and main stem bronchial regions in all fluoroscopic videos and radiographic images for evidence of collapse. Cervical, thoracic inlet, thoracic, and carinal regions in both radio-graphic and fluoroscopic studies were graded for collapse (0%, 25%, 50%, 75%, or 100% decrease in diameter). RESULTS: Lateral cervical and thoracic radiographic images were available for 54 dogs, and inspiratory and expiratory lateral cervical and thoracic radiographic images were available for 8 dogs. For detection of tracheal collapse, assessment of radiographic views was sensitive and had the best negative predictive value in the cervical and thoracic inlet regions. Assessment of radiographic views was most specific and had the best positive predictive value in the thoracic inlet, thoracic, carina, and main stem bronchial regions. Radiography underestimated the degree of collapse in all areas. Review of inspiratory and expiratory views improved the accuracy of radiography for tracheal collapse diagnosis only slightly. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with fluoroscopy, radiography underestimated the frequency and degree of tracheal collapse. However, radiography appears to be useful for screening dogs with potential tracheal collapse.     

Acute tracheal obstruction associated with anticoagulant rodenticide intoxication in a dog

An adult female neutered crossbred dog was referred in respiratory distress. Thoracic radiographs revealed tracheal narrowing with a soft tissue opacity dorsal to the trachea, near the thoracic inlet, and a patchy interstitial pulmonary infiltrate. The tracheal narrowing was thought to be due to a combination of intraluminal haemorrhage and mediastinal haemorrhage resulting from a coagulopathy caused by anticoagulant rodenticide intoxication. Treatment included supportive care and administration of vitamin K1, and the dog showed a complete resolution of the clinical signs.     

Pericardial effusion and cardiac tamponade in a cat with extranodal lymphoma

A five-year-old domestic longhaired cat was evaluated for a seven-day history of worsening respiratory distress. Serum analysis for feline leukaemia virus antigen was positive. Pleural effusion was detected on thoracic radiographs and echocardiography revealed a pericardial effusion and cardiac tamponade. Cytological evaluation of the pleural and pericardial effusions showed lymphoblastic cells indicative of disseminated lymphoma. Following thoracocentesis and pericardiocentesis, the cat was treated for lymphoma using the University of Wisconsin-Madison chemotherapy protocol. The cat was sent home after three days and, at the time of writing (six months after initial presentation), was still symptom free. To the authors' knowledge, this is the first report confirming pericardial effusion and cardiac tamponade in the cat as a direct result of an extranodal lymphoma with cytological evidence of neoplastic cells in the pericardial fluid.     

Segmental tracheal dysplasia in a mixed breed dog

A 6-month-old, spayed female, mixed breed dog was referred for respiratory difficulty. Radiographic and bronchoscopic evaluations showed tracheal narrowing from the thoracic inlet to its bifurcation. Under anesthesia, the trachea ruptured and the dog died. Microscopic evaluation revealed underlying segmental tracheal and bronchial cartilaginous malformation (dysplasia).     

Thoracic vertebral osteochondroma in a cat

A thoracic vertebral (T5) osteochondroma was discovered in a 1 1/2-year-old male blue Persian cat with a history of acute hind limb paresis. Myelography revealed a mass on the dorsal surface of the vertebral body, which resulted in dorsal compression of the spinal cord. A dorsal laminectomy was performed, and the mass was rongeured entirely from the vertebral body. Although the cat's progress was initially slow after surgery, its neurologic status was assessed to be near normal, 15 months later.     

Radiographic and computed tomographic appearance of tracheal collapse with axial rotation in four dogs

Tracheal collapse with axial rotation was diagnosed in four dogs. Radiographs showed increased tracheal dorsoventral height at the caudal cervical and thoracic inlet with and apparent intraluminal soft tissue opacity, mimicking an intraluminal tracheal foreign body. Computed tomography confirmed dorsoventral tracheal collapse with axial rotation in all dogs. Short‐term outcome with medical treatment of all dogs was excellent.     

Tracheal resection and anastomosis for congenital stenosis in a dog

A one-year-old Cocker Spaniel dog was presented for the investigation of exercise-related stridor and respiratory embarrassment evident since birth. Radiography demonstrated a segmental tracheal stenosis at the thoracic inlet which was found to result from the congenital absence of tracheal rings at this point. The stenotic segment was resected at surgery and an end-to-end tracheal anastomosis performed. The dog now enjoys normal respiratory and exercise function with minimal narrowing of the trachea at the site of the anastomosis.     

Mediastinal lymphoma in a young Turkish Angora cat

An 8-month old intact male Turkish Angora cat was referred to the Veterinary Medical Teaching Hospital (VMTH), Seoul National University, for an evaluation of anorexia and severe dyspnea. The thoracic radiographs revealed significant pleural effusion. A cytology evaluation of the pleural fluid strongly suggested a lymphoma containing variable sized lymphocytes with frequent mitotic figures and prominent nucleoli. The feline leukemia virus and feline immunodeficiency virus tests were negative. The cat was euthanized at his owner''s request and a necropsy was performed. A mass was detected on the mediastinum and lung lobes. A histopathology evaluation confirmed the mass to be a lymphoma. Immunohistochemistry revealed the mass to be CD3 positive. In conclusion, the cat was diagnosed as a T-cell mediastinal lymphoma.     

Incomplete tracheal intussusception in a dog

An 18-year-old male miniature poodle had a chronic nonproductive cough. On radiographic examination, an opacification resembling a foreign body was noticed within the trachea at the level of the sixth cervical vertebra. When the trachea was examined endoscopically, a circumferential flap-like lesion was found. To differentiate the invagination from an annular mass, thoracic computed tomography (CT) of the trachea was performed. There was cranial displacement and invagination of a tracheal segment creating the flap-like lesion. Tracheal intussusception should be considered as a cause of an annular tracheal mass.     

Vaccine-associated rhabdomyosarcoma with spinal epidural invasion and pulmonary metastasis in a cat

A 7-year-old, female, domestic medium-haired cat had a recurrent deep dermal mass in the interscapular region after initial surgical removal 3 months earlier. The cat had received a killed rabies vaccine and a five-in-one vaccine in the same area about 2 months prior to the first surgery. The relapsed mass was diagnosed as vaccine-associated sarcoma. The cat was euthanized 2 months later because of hind limb paralysis. At necropsy, multiple, poorly demarcated, nodular masses were seen in the muscles around the shoulders, neck, and thoracic vertebrae. Pulmonary metastasis and spinal epidural invasion at T1-T3 with regional cord compression and malacia were observed. Microscopically, the masses consisted of interwoven bundles of spindle cells with prominent multinucleated giant cell formation. The neoplastic cells stained strongly positive for myoglobin, and moderately but variably positive for vimentin, desmin, and alpha- smooth muscle actin. Phosphotungstic acid-hematoxylin staining revealed cytoplasmic striations in scattered tumor cells. The tumor was considered a vaccine-associated rhabdomyosarcoma.