Management of bilateral choanal atresia in a foal

CASE DESCRIPTION: A 1-day-old Standardbred foal with a history of extreme respiratory distress after birth consistent with upper airway obstruction was evaluated. A temporary tracheostomy tube was placed by the referring veterinarian. CLINICAL FINDINGS: On initial examination, there was evidence of hypoxic-ischemic syndrome, secondary to perinatal asphyxia. Endoscopy revealed obstruction of both nares at the level of the choanae; a diagnosis of bilateral choanal atresia was made. TREATMENT AND OUTCOME: The foal was anesthetized and underwent transendoscopic laser fenestration of the buccopharyngeal membranes. Three weeks after surgery, cicatricial narrowing of the choanae was apparent and further transendoscopic ablation was performed. Recurrent stenosis necessitated revision surgeries involving a combination of laser ablation with topical administration of mitomycin and, subsequently, a combination of radial incisions into the stenotic tissue and repeated bougienage with a cuffed endotracheal tube. The degree of stenosis decreased, and at 1 year of age, the horse was an appropriate size for its age, had choanae that were almost maximally open (> 85%), and had entered training. Mild stenosis was still evident when the horse was reexamined the following year, although there was no evidence of exercise intolerance or respiratory compromise. CLINICAL RELEVANCE: Bilateral choanal atresia in a foal can be successfully treated via transendoscopic fenestration of the buccopharyngeal membranes, enabling the horse to subsequently participate in athletic activities. Secondary problems resulting from initial asphyxia and recurrent stenosis at the surgical site can be overcome but may require prolonged and extensive treatment.     

Endoscopic electrosurgical excision of laryngeal granulation tissue in a standing pregnant mare

An 11-year-old, eight-months pregnant mare suddenly developed severe respiratory distress. Endoscopic examination identified intralaryngeal granulation tissue obstructing the airway. In order to avoid general anaesthesia and the problems associated with a permanent tracheostomy, the mass was resected electrosurgically while the mare was standing. Patency was restored to the airway and the mare foaled without complication.     

The use of intraluminal stents for tracheal collapse in two horses: Case management and long‐term treatment

Tracheal collapse is an uncommon clinical disorder in horses but when present can be difficult to correct. Various medical and surgical procedures to correct tracheal collapse have been described in horses with variable success. Recently, the use of an intraluminal stent has been described as a treatment for tracheal collapse in a miniature horse. The long‐term management, utilising intraluminal stents, in 2 miniature horses with tracheal collapse is presented here. In particular, various complications as a result of intraluminal stent placement are described, the most persistent being the formation of granulation tissue at various regions of the stents. Multiple methods of combating granulation tissue in this situation also are discussed.     

Use of intraluminal nitinol stents in the treatment of tracheal collapse in a dog

Tracheal collapse is a common problem that is typically observed in middle-aged and older small-breed dogs. It is a structural, obstructive airway disease with a dynamic component that can affect the intra- and extrathoracic portions of the trachea and mainstem bronchi. Many methods of treatment have been suggested, including medical management and provision of extraluminal and intraluminal support. All techniques used to treat intrathoracic and mainstem bronchial collapse have been associated with major complications or limitations. This report describes the implantation of intraluminal nitinol stents to successfully treat intrathoracic as well as extrathoracic tracheal collapse in a dog. The stents are composed of material that has characteristics similar to those of the trachea; nitinol stents may provide a method of supporting intrathoracic tracheal and mainstem bronchial collapse in dogs.     

Surgical repair of ruptured trachea in a horse

An Arabian mare was referred with traumatically induced complete transection of the trachea. A temporary airway was established through the open wound at the site of the rupture. Resection of devitalized tissue including 3 tracheal ring segments, and anastomosis of the tracheal ends was subsequently performed under general anesthesia. Wound healing was complicated by a peritracheal abscess, which responded successfully to drainage and antibiotic administration.     

Bilateral choanal atresia in a cat

A 7-month-old female spayed domestic shorthair cat was presented for investigation of stertor, open mouth breathing without apparent distress, and chronic bilateral nasal discharge that was unresponsive to antibiotics. Complete bilateral bony choanal atresia was diagnosed with computed tomography and nasopharyngoscopy. Choanal atresia is an uncommon congenital condition where the choana (nasal passage into the nasopharynx) is blocked by abnormal bone or soft tissue uni- or bilaterally. The cat's clinical signs improved dramatically immediately after trans-palatal surgical correction. Post-surgical complications included the development of nasopharyngeal scar tissue and subsequent stenosis, persistent right-sided nasal discharge, and permanent damage to the right eye (blindness and cataract formation). Nasopharyngeal stenosis was managed with repeated balloon dilatations and temporary stenting, and the owner reported an excellent quality of life at 8-month follow-up. Bilateral bony choanal atresia has not been previously reported in cats. Uni- or bilateral choanal atresia should be considered in young cats presenting with refractory stertor, chronic nasal discharge, and/or open mouth breathing.     

Surgical Correction of Congenital Bilateral Choanal Atresia in a Foal

Congenital bilateral choanal atresia was corrected surgically in a neonatal foal. Presenting clinical signs included complete obstruction of the upper airway, which had been relieved by tracheotomy. The diagnosis was confirmed by endoscopic examination and contrast radiography. Bilateral nasal flaps were used to gain access to the caudal nasal cavity, allowing removal of obstructive tissue and restoration of normal respiration. Malocclusion developed secondary to surgical intervention and resultant damage to suture lines of developing flat bones of the skull. Nine months postoperatively, the asynchronous growth of the mandible and maxilla had not resulted in difficulty during mastication. Respiration, although audible during periods of exercise, was acceptable to the owners.     

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.     

Tracheal perforation managed by temporary tracheostomy in a horse

Tracheal trauma with resultant rupture is uncommonly reported in veterinary literature. We report the case of a 16-year-old Thoroughbred gelding that sustained a 1 cm longitudinal perforation of the dorsal tracheal membrane in the proximal cervical region. The horse subsequently developed dyspnoea due to acute upper respiratory obstruction secondary to severe emphysema of the guttural pouches. A temporary tracheostomy caudal to the site of tracheal perforation was performed under local anaesthesia. This procedure helped relieve the upper airway obstruction and aided resolution of the injury by diverting air away from the site of tracheal perforation. After conservative management, the gelding recovered completely.     

Nodular immunocyte-derived (AL) amyloidosis in the trachea of a dog

A 7-year-old castrated male Miniature Schnauzer was examined because of labored breathing and episodes of respiratory distress that progressed to collapse. On cervical radiographs, a focal soft tissue mass in the caudal cervical portion of the trachea was observed, and during tracheoscopy, a 1 x 1 cm, pedunculated, multinodular, pink, intraluminal mass extending from the dorsal tracheal membrane and obstructing approximately 80% of the tracheal lumen was seen. Tracheal resection and anastomosis was performed to remove the mass, and the dog recovered without complications. On histologic examination, the mass consisted of a large accumulation of homogeneous, faintly fibrillar eosinophilic material admixed with a predominantly plasma cell infiltrate; examination of sections stained with thioflavin T and Congo red stain confirmed that the eosinophilic material was amyloid. A diagnosis of nodular, immunocyte-derived (AL) amyloidosis was made. Seventeen months after surgery, the dog had a relapse of respiratory distress because of an extramedullary plasmacytoma involving the trachea.     

Choanal atresia in a cat

CASE HISTORY: A 5-month-old domestic shorthair kitten with a history of chronic left unilateral nasal discharge was examined.

CLINICAL FINDINGS: Endoscopy and computed tomography (CT) demonstrated a complete membranous obstruction of the left nasal choana, confirming congenital unilateral choanal atresia. In addition, congenital hydrocephalus was detected on CT. Nasopharyngoscopy was performed for confirmation and treatment of choanal atresia.

DIAGNOSIS: Unilateral membranous choanal atresia associated with congenital hydrocephalus.

CLINICAL RELEVANCE: This report describes a rare congenital condition and for the first time, CT imaging provided an accurate diagnosis and allowed planning for the successful treatment of unilateral membranous choanal atresia. In addition, concurrent congenital hydrocephalus was diagnosed.     

An in vivo model for the study of Bordetella avium adherence to tracheal mucosa in turkeys

An in vivo model was developed for studies characterizing the adherence of Bordetella avium to the tracheal mucosa of turkeys. Three-week-old turkeys were anesthetized, and the cervical part of the trachea was isolated after tracheostomy was done. A hemostat was applied craniad to the tracheostomy site to occlude the tracheal lumen. Isolated tracheal segments were filled with an aqueous bacterial inoculum for 1 minute, and then excess inoculum and the hemostat were removed. After 1 hour, a 1-cm section was excised from each tracheal segment, and adherent viable bacteria were quantified. Modifications of the procedure were evaluated to produce a model that was technically simple to do, economical, and reproducible. To examine the validity of the model, adherence of B avium was compared with that of Escherichia coli and Staphylococcus aureus. Adherence of B avium to tracheal mucosa was 17 times greater than that with E coli and 1,550 times greater than that with S aureus. Colonization of the tracheal mucosa by B avium was demonstrated in tracheal sections obtained 6 hours after filling with bacterial inoculum. Because the ciliary clearance mechanism of the tracheal segments remained functional, washing of the tracheal lumen had no effect on numbers of associated bacteria. An important advantage of this model over in vitro models is the excellent preservation of the tracheal mucosal surface.     

Tracheal necrosis as a fatal complication of endotracheal intubation

This case report describes the death of a yearling Thoroughbred colt due to segmental severe necrotising tracheitis with stenosis of the tracheal lumen, 19 days after endotracheal intubation for elective endoscopic surgery. The stenosis of the trachea leading to asphyxiation was caused by an inflammatory process accompanied by massive accumulation of necrotic material, fibrinous inflammatory exudate, oedema and granulation tissue. The cause of this inflammation was likely to be a bacterial infection secondary to traumatic damage of the tracheal mucosa. Given the clinical history and location of the lesion, the endotracheal tube used for general anaesthesia was hypothesised to be responsible for this damage. Delayed tracheal necrosis as a fatal complication of endotracheal intubation has not previously been described in the horse and should be considered as a potential catastrophic consequence following relatively innocuous clinical signs.     

COMPUTED TOMOGRAPHIC APPEARANCE OF CHOANAL ATRESIA IN AN ALPACA CRIA

A 6-hour-old alpaca cria was admitted for evaluation of respiratory distress since birth. Contrast radiography confirmed the presence of bilateral choanal atresia, and computed tomography (CT) evaluation was planned to aid in the surgical treatment. Due to deterioration in the cria's condition, euthanasia was performed prior to the CT examination. Postmortem CT examination was performed to determine the appearance of choanal atresia. The embryology and CT appearance of choanal atresia is discussed.     

Dynamic tracheal collapse as a cause of exercise intolerance in a thoroughbred

A 2-year-old Thoroughbred filly was admitted to the hospital for evaluation of exercise intolerance. Resting videoendoscopic evaluation (i.e., while the horse was standing) of the nasopharynx and trachea revealed right arytenoid paresis and a tracheal defect that was 100 cm distal to the external nares. Surgery, consisting of a right prosthetic laryngoplasty, was performed. However, postoperative videoendoscopic evaluation revealed minimal abduction of the affected arytenoid cartilage. Dynamic videoendoscopic evaluation (i.e., while the horse was exercising) revealed the right arytenoid to be fixed in a submaximal position with no evidence of collapse into the airway. When the endoscope was positioned in the midcervical tracheal region, marked tracheal collapse was identified during exercise. Tracheal collapse can critically limit athletic function. Treatment of tracheal collapse depends on causative factors, the length of the trachea involved, and accessibility of the affected tracheal segment. The use of dynamic tracheal videoendoscopy should be considered in athletic horses with exercise intolerance in which the cause cannot be determined from resting or dynamic videoendoscopic evaluations of the nasopharynx.     

Computed Tomographic Features of Choanal Atresia in a Friesian Foal

A 3-week-old Friesian colt with a history of respiratory distress since birth was presented to our facility. Results after an endoscopy showed obstruction of the right nasal passage to the nasopharynx. Computed tomography was performed to further characterize this unilateral blockage. The images demonstrated a complete membranous obstruction of the ventral meatus, along with deviation of the vomer bone toward the left side of the nasal cavity. The diagnosis of unilateral choanal atresia was confirmed. This report is the first to describe computed tomographic features of choanal atresia in a foal.     

Intraluminal tracheal stent fracture in a Yorkshire terrier

An 8-year-old Yorkshire terrier was presented with tracheal collapse. Two intraluminal nitinol stents were implanted. The implanted stents were found to be fractured 4 weeks after implantation. The fractured stents were removed. To restore the collapsed trachea, ring prostheses were applied. However, the dog was euthanized because of a bad outcome following surgery.     

Surgical management of atypical lateral tracheal collapse in a dog

A FOUR-year-old spayed miniature poodle was presented for evaluation because of a chronic cough which had been present from eight weeks of age. The condition had gradually worsened until exercise intolerance, inappetence and abdominal breathing occurred. The dog was thin and weighed only 1.5 kg. Auscultation revealed tachycardia, a normal respiratory rate and wheezing noises - more prominent on inspiration and localised to the cervical portion of the trachea. There was marked inspiratory and expiratory effort. Tracheal sensitivity was moderate and palpation induced a dry hacking cough. Radiography demonstrated mild thickening of the bronchial wall and pulmonary hyperinflation. Expiratory/inspiratory radiographs failed to demonstrate dynamic tracheal collapse. On fluroscopy, substantial changes in tracheal calibre were not apparent. Bronchoscopy was performed and the tracheal lumen was normal up to 12.5 cm from the incisors. At this point, there was lateral tracheal collapse to about 30 per cent. There was dynamic collapse with respiratory effort. The bronchoscope could be passed beyond the narrowing (consisting of five tracheal rings) to a trachea of normal size. No pathogens were found on tracheal lavage. Surgery was undertaken through a midline, ventral approach. Six specially made tracheal ring prostheses were individually inserted around the trachea and inside the recurrent laryngeal nerve. Each prosthesis was sutured in four places to the tracheal ring, to give external support. The dog improved clinically and 11 months after surgery, bronchoscopy was again performed. The trachea was narrowed to approximately 60 per cent but there was no dynamic collapse of the airway. Twenty-seven months after surgery the dog continued to lead a healthy active life.     

Pneumomediastinum, pneumothorax and pneumoretroperitoneum following endoscopic retrieval of a tracheal foreign body from a cat

A 6-year-old entire male cat was presented with a 1-week history of severe dyspnoea without coughing. Upon auscultation, an inspiratory and particularly pronounced expiratory wheeze was noted, with severe dyspnoea. The minimum database was normal. Plain thoracic radiographs showed signs of a mural or intraluminal intrathoracic (T1-T4) tracheal narrowing. A dynamic collapsing trachea was ruled out using fluoroscopy. Bronchoscopy was performed and a dark green and brown spiculated foreign object was found just cranial to the carina. Following removal, the cat rapidly developed extensive truncal subcutaneous emphysema and oxygen-responsive dyspnoea and cyanosis. Follow-up radiographs demonstrated unilateral pneumothorax and lung collapse, marked pneumomediastinum and dissection of air through the tracheal wall. A thoracic drain was placed and the pneumothorax resolved rapidly. Follow-up radiographs demonstrated resolution of pneumothorax and development of extensive retroperitoneal air. The cat made an uneventful recovery. The foreign object was the calyx and stem of a flower. This article emphasises the importance of diagnostic imaging in the dyspnoeic patient, both for confirming initial suspicions of respiratory tract disease, and in managing and charting post-therapy resolution or complications.     

Resection of a cervical tracheal bronchus in a foal

A 3-day-old Thoroughbred foal developed a large, air-distended, midcervical swelling that was diagnosed as a congenital tracheal bronchus with associated ectopic lung tissue. Clinical signs consisted of a compressible air-filled sac that enveloped the trachea. The nature and extent of the defect were evaluated endoscopically and radiographically. Surgical resection of the bronchus and associated air-filled sac resulted in a functionally and cosmetically acceptable outcome.