Balloon dilation and transient stenting of unilateral membranous choanal atresia in a British Shorthair cat with chronic purulent rhinitis and ascending meningoencephalitis.

INTRODUCTION: Choanal atresia is a rare congenital anomaly in humans and animals, characterized by the absence of communication of one or both nasal cavities with the nasopharynx. The severity of clinical signs depends on the presence of unilateral versus bilateral stenosis as well as comorbidities. With bilateral atresia, respiration may be severely compromised particularly during sleep, as airflow can only occur when breathing through the open mouth. Various therapeutic modalities have been described in people and adopted for animals. All treatments may be associated with complications, the most important being post-therapeutic scar formation with re-stenosis. This report describes a 10-month-old British Shorthair cat with chronic unilateral serosal nasal discharge that changed to mucopurulent discharge. When acute neurological signs developed, the cat was presented to the veterinary hospital. A diagnosis of primary, membranous right sided choanal atresia was achieved via computed tomography (CT) and nasopharyngeal (posterior) rhinoscopy. Secondary changes included destructive rhinitis with progression to the CNS with a subdural empyema and meningoencephalitis. Retinal changes and aspiration bronchopneumonia were suspected additional complications. After recovery from the secondary infections, the membranous obstruction was perforated and dilated using a valvuloplasty balloon by an orthograde transnasal approach under endoscopic guidance from a retroflexed nasopharyngeal view. To prevent re-stenosis, a foley catheter was placed as a transient stent for 6 days. The cat recovered uneventfully and was asymptomatic after the stent removal. Endoscopic re-examination after 5 months confirmed a persistent opening and patency of the generated right choanal passage. The cat remains asymptomatic 10 months after the procedure. Transnasal endoscopic balloon dilation and transient stenting of choanal atresia is a minimally invasive and relatively simple procedure with potentially sustained success.

INTRODUCTION: L'atrésie des choanes est une anomalie congénitale rare chez l'homme et l'animal, caractérisée par l'absence de communication d'une ou des deux cavités nasales avec le nasopharynx. La gravité des signes cliniques dépend de la présence d'une sténose unilatérale ou bilatérale, ainsi que des comorbidités. En cas d'atrésie bilatérale, la respiration peut être gravement compromise, en particulier pendant le sommeil, car l'air ne peut circuler que par la bouche ouverte. Diverses modalités thérapeutiques ont été décrites chez l'homme et adaptées pour les animaux. Tous les traitements peuvent être associés à des complications, la plus importante étant la formation de cicatrices post-thérapeutiques avec resténose. Ce rapport décrit un chat British Shorthair de 10 mois présentant un écoulement nasal séreux unilatéral chronique qui s'est finalement transformé en un écoulement muco-purulent. Lorsque des signes neurologiques aigus sont apparus, le chat a été présenté à l'hôpital vétérinaire. La tomodensitométrie (CT) et la rhinoscopie nasopharyngée (postérieure) ont permis de diagnostiquer une atrésie choanale primaire membraneuse du côté droit. Les altératiins secondaires comprenaient une rhinite destructrice avec une progression vers le SNC avec empyème sous-dural et méningo-encéphalite. Des altérations de la rétine et une bronchopneumonie par aspiration étaient des complications supplémentaires présumées. Après guérison des infections secondaires, l'obstruction membraneuse a été perforée et dilatée à l'aide d'un ballonnet de valvuloplastie par une approche transnasale orthograde sous guidage endoscopique à partir d'une vue nasopharyngée rétrofléchie. Pour éviter une nouvelle sténose, une sonde de Foley a été placée comme stent transitoire pendant 6 jours. Le chat s'est rétabli sans incident et était asymptomatique après le retrait du stent. Le réexamen endoscopique effectué 5 mois plus tard a confirmé la persistance de l'ouverture et de la perméabilité de la voie choanale droite générée. Le chat reste asymptomatique 10 mois après l'intervention. La dilatation endoscopique transnasale par ballonnet et la pose d'une endoprothèse transitoire dans le cas d'une atrésie des choanes est une procédure peu invasive et relativement simple dont le succès peut être durable.

Transpalatal reconstruction and stenting for treatment of choanal atresia and nasopharyngeal stenosis in a dog.

CASE DESCRIPTION: A 3-year-old 17.5-kg (38.5-lb) mixed-breed dog was referred for evaluation because of nasal discharge, sneezing, and signs of nasal congestion of approximately 9 months' duration. A diagnosis of nasopharyngeal stenosis (NPS) was made prior to referral. CLINICAL FINDINGS: Sneezing, bilateral mucopurulent nasal discharge, reduced nasal airflow, stertor, and increased inspiratory effort were noted on physical examination. Results of serum biochemical analysis were within respective reference ranges. Review of CT images of the skull revealed findings consistent with severe bilateral partial osseous choanal atresia and NPS. Retrograde rhinoscopy confirmed membranous NPS. TREATMENT AND OUTCOME: A ventral rhinotomy was performed; communication between the pharynx and nasal passageway was reestablished by surgical debridement of the caudal border of the palatine bone and vomerine crest and groove, followed by dissection of the membranous NPS and reconstruction of the caudal part of the nasopharynx. A covered nasopharyngeal stent was placed in the newly established nasopharynx. The dog recovered uneventfully but was presented 3 weeks later with recurrent signs; diagnostic findings were consistent with stenosis rostral to the stent. The stenosis was treated with balloon dilation, and a second covered stent was placed rostral to and overlapping the first stent, spanning the stenotic region. Eleven months after this procedure, the dog was doing well. CLINICAL RELEVANCE: Results for this patient suggested that ventral rhinotomy and covered nasopharyngeal stent placement can be used successfully for the management of osseous choanal atresia in dogs; however, careful attention to preoperative planning and potential complications is necessary.

Use of a novel surgical approach for treatment of complete bilateral membranous choanal atresia in an alpaca cria.

CASE DESCRIPTION A 4-hour-old 6.3-kg (13.9-lb) female alpaca cria was evaluated because of severe respiratory distress and difficulty nursing since birth. CLINICAL FINDINGS The cria had open-mouth breathing and cyanotic membranes, with no airflow evident from either nostril. Supplemental oxygen was delivered, and the patient was anesthetized and intubated orotracheally; a CT evaluation of the head confirmed bilateral membranous obstruction of the nasal cavities, consistent with complete bilateral choanal atresia. TREATMENT AND OUTCOME Choanal atresia was treated with an endoscopically assisted balloon-dilation technique, and temporary tracheostomy was performed. Stenosis recurred, requiring revision of the repair and intranasal stent placement 3 days after the first surgery. The tracheostomy tube was removed the next day. Complications during hospitalization included mucoid obstruction of the tracheostomy tube, granulation tissue development in the trachea near the tracheostomy site, mucoid stent obstruction, aspiration pneumonia, and presumed partial failure of passive transfer of immunity. The stents were removed 2 weeks after admission, and the cria was discharged 3 days later. The owner was advised that the animal should not be bred. At last follow-up 3 years later, the alpaca was doing well. CLINICAL RELEVANCE Surgical treatment with a balloon-dilation technique and placement of nasal stents with endoscopic guidance were curative in this neonatal alpaca with bilateral membranous choanal atresia. Computed tomography was useful to determine the nature of the atresia and aid surgical planning. Because a genetic component is likely, owners should be advised to prevent affected animals from breeding.

Evaluation of CHD7 as a candidate gene for choanal atresia in alpacas (Vicugna pacos).

Choanal atresia (CA) is a craniofacial malformation characterized by obstruction of the posterior nasal aperture, resulting in laborious respiratory inspiration and exhalation. Alpaca crias with CA typically develop fatal pneumonia, frequently as the result of milk aspiration during nursing, and euthanasia is usually inevitable. Nonsense or missense mutations in the CHD7 gene cause a comparable condition (CHARGE syndrome) in humans. In this study, the coding region of CHD7 was sequenced in six CA-affected alpacas. Forty-nine sequence variants were identified, of which 10 would result in amino acid changes (non-synonymous), some with potentially deleterious effects. However, none of the observed variants would result in the obvious deleterious effects caused by nonsense or missense mutations. Although a role for CHD7 mutations in CA cannot be definitively dismissed, these do not appear to be the primary cause of CA in alpacas.

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.

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.

A candidate gene for choanal atresia in alpaca.

Choanal atresia (CA) is a common nasal craniofacial malformation in New World domestic camelids (alpaca and llama). CA results from abnormal development of the nasal passages and is especially debilitating to newborn crias. CA in camelids shares many of the clinical manifestations of a similar condition in humans (CHARGE syndrome). Herein we report on the regulatory gene CHD7 of alpaca, whose homologue in humans is most frequently associated with CHARGE. Sequence of the CHD7 coding region was obtained from a non-affected cria. The complete coding region was 9003 bp, corresponding to a translated amino acid sequence of 3000 aa. Additional genomic sequences corresponding to a significant portion of the CHD7 gene were identified and assembled from the 2x alpaca whole genome sequence, providing confirmatory sequence for much of the CHD7 coding region. The alpaca CHD7 mRNA sequence was 97.9% similar to the human sequence, with the greatest sequence difference being an insertion in exon 38 that results in a polyalanine repeat (A12). Polymorphism in this repeat was tested for association with CA in alpaca by cloning and sequencing the repeat from both affected and non-affected individuals. Variation in length of the poly-A repeat was not associated with CA. Complete sequencing of the CHD7 gene will be necessary to determine whether other mutations in CHD7 are the cause of CA in camelids.

Management of neonatal llamas and alpacas.

Most llama and alpaca crias will be born without complication and survive the neonatal period without incident. However, it is important to be able to recognize which crias are likely to be at risk of complications so that you are best able to advise owners and take the correct course of action if required. This article deals with management of the pregnant camelid, the events associated with parturition and the peripartum period with emphasis on the cria, management of the newborn cria including assessment of passive transfer of immunity, issues relating to prematurity, and the major congenital defects that may present as emergencies within the neonatal period.

Choanal atresia in a Himalayan cat--first reported case and successful treatment.

A 2-year-old Himalayan cat was presented for investigation of chronic, persistent, unilateral nasal discharge that was unresponsive to antibiotics. Unilateral choanal atresia was diagnosed on nasopharyngoscopy. Following surgical repair using the transnasal route and temporary stenting all clinical signs resolved. This is the first reported case of choanal atresia in a cat. It serves to alert practitioners to the occurrence of this unusual condition which should be included in the differential diagnoses of upper respiratory tract signs in young cats.

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.

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.

Disorders of the pharynx.

Pharyngeal disorders are complex and difficult to treat. Disorders that lead to anatomic derangement, such as trauma and neoplasia, can significantly affect the function of this organ. Pharyngeal dysfunction can manifest as dysphagia, persistent palatal displacement, or exercise intolerance. Secondary complications are serious and life threatening and include aspiration pneumonia, weight loss, and death. Pharyngeal disorders that are only recognizable during strenuous exercise are difficult to diagnose and are treated with limited success, even though they are responsible for significant economic losses with performance animals.

Choanal atresia and secondary nasopharyngeal stenosis in a dog.

A 20-month-old, intact male shih tzu was evaluated for chronic upper airway disease. Endoscopic examination established a diagnosis of choanal atresia, a developmental anomaly of the posterior nasal cavity. Although surgical intervention provided temporary relief, stenosis of the nasopharynx by obstructive scar tissue was confirmed within four weeks. A permanent tracheostomy provided long-term relief of the respiratory difficulty. This is the first report of choanal atresia or nasopharyngeal stenosis in a dog.

Spontaneous cleft palate in a newborn gorilla (Gorilla gorilla gorilla).

OBJECTIVE: We report the first case of cleft palate in a newborn male gorilla (Gorilla gorilla gorilla). CASE HISTORY AND RESULTS: The full-term infant was born to clinically healthy, wild-caught parents and survived 5 days. Autopsy disclosed a unilateral cleft palate, moderate scalp hemorrhage (birth versus postnatal trauma), cerebral edema, and a sterile fibrin vegetation in the heart. The palate was also shorter and narrower than expected, and the biorbital breadth was reduced; otherwise, growth and development appeared normal. Standard cranial and intraoral radiographs and three-dimensional reconstructions of computerized tomographic (CT) scans provided thorough and noninvasive methods of studying the craniofacial complex and extracranial skeleton. By this technique, major findings were: intact premaxilla, interpremaxillary, and premaxillary/maxillary sutures; intramaxillary cleft with ipsilateral choanal atresia; mildly asymmetric inferior turbinates; and normal nasal septum and vomer. CONCLUSIONS: Except for choanal atresia, cleft palate was not associated with other major craniofacial or extracranial anomalies in this case. Choanal atresia has been observed at times with cleft palate, but to our knowledge, the association has not been reported in nonhuman primates. Cleft palate, with or without cleft lip, has been recognized in a variety of nonhuman primates, including the lemur, marmoset, tamarin, squirrel monkey, and macaque. Some occurrences are spontaneous, while others are syndromic and/or arise from genetic or teratogenic influences. Each mode of presentation is poorly understood in nonhuman primates, but in this case, the absence of relevant environmental or parental history suggests that the occurrence was spontaneous. Anatomic studies of nonhuman primates are particularly valuable when they involve endangered species and will hopefully increase our understanding of the pathogenesis and etiology of congenital disorders, as well as other relationships between nonhuman primates and humans.

Unilateral choanal atresia in a foal.

A 4-month-old Thoroughbred foal was examined because of a history of exercise intolerance and lack of airflow from the right nostril since birth. Endoscopy of the airways revealed complete membranous obstruction of the right nasal passage at the level of the nasopharynx and marked narrowing of the caudal aspect of the right ventral meatus. Unilateral choanal atresia was diagnosed. Laser ablation of the obstructing tissues was attempted through a videoendoscope. Scar tissue occluded the right nasal passage at follow-up examination 7 weeks later. Intranasal resection, using laparoscopic instruments, was then performed, and a nasal stent was maintained for 2 weeks after surgery. At 1 year of age, the foal was reported to have decreased airflow from the right nares and excessive respiratory noise during exercise. Atresia of the choanae in horses usually is bilateral and, therefore, life-threatening and detectable at birth. Unilateral choanal atresia may not be suspected until later, but should be considered in horses with decreased or no airflow from 1 naris.

Congenital diseases of the equine head.

Many questions concerning heritability arise when a veterinarian is asked to supervise and treat disease of congenital origin. Genetic counseling, ethics, and legality are often confronted in discussions between animal health professionals and laymen in animal industry. Guidelines have been offered as in the 1984 statement of the Judicial Council of the American Veterinary Medical Association: "Performance of surgical procedures in all species for the purpose of concealing genetic defects in animals to be shown, raced, bred, or sold as breeding animals is unethical. However, should the health or welfare of the individual patient require correction of such genetic defects, it is recommended that the patient be rendered incapable of reproduction." The Australian Veterinary Law, Ethics, Etiquette and Convention declares it fraud to alter a defect for sale purposes and unethical for a veterinarian to perform such treatments. It is permissible to correct defects causing discomfort or inconvenience, but the veterinarian is required to advise appropriate breeding counseling. Genetic counseling has progressed significantly in human medicine. This has been supported by better diagnostic methods for genetic disorders, greater acceptance of preventive measures, and extended screening programs to identify carriers of specific abnormal genes or chromosomal aberrations. Congenital diseases in veterinary medicine are constantly under investigation. The veterinary practitioner must continue to operate with an appreciation of the incomplete understanding of most of these abnormalities and act in accordance with personal ethical judgment and the guidance of the American Veterinary Medical Association when treating the affected individual animal patient.