URT Surgery in Small Animals

URT Surgery in Small Animals Notes

Pathophysiology - Primary & Secondary Factors

  • Stenotic external nares: Narrowed nostrils that significantly hinder airflow to the lungs, often causing increased respiratory effort and distress.

  • Relative overlength and hypertrophy of the soft palate: An excessively long or thick soft palate can lead to turbulent airflow and increased respiratory noise, negatively impacting the quality of life.

  • Tonsillar hypertrophy: Enlarged tonsils can obstruct the airway, particularly during inspiration, compounding respiratory issues in brachycephalic breeds.

  • Relative oversize of the tongue: A disproportionately large tongue can obstruct airflow, especially in breeds with short heads (brachycephalics), leading to obstructive sleep apnea and other complications.

  • Everted laryngeal ventricles/saccules: This condition causes eversion of the laryngeal vents, which can obstruct the airway and is often associated with other anatomical abnormalities.

  • Laryngeal collapse: A serious condition wherein the supporting structures of the larynx lose their rigidity, resulting in significant airway narrowing during respiration.

  • Pharyngeal collapse: A condition occurring concurrently with laryngeal collapse, further complicating airflow and clinical presentation in affected animals.

  • Tracheal hypoplasia/stenosis: This refers to an abnormally small or narrowed trachea, leading to reduced airflow capacity and increased risk for respiratory distress.

  • Glosso-epiglottic mucosa displacement: Displacement of the mucosal tissue surrounding the base of the epiglottis may obstruct the airway, particularly during swallowing or respiratory efforts.

  • Scrolling of epiglottic cartilage: Abnormal cartilage development can cause the epiglottis to obstruct the airway, often requiring surgical intervention.

  • Vomiting/regurgitation: These conditions can lead to aspiration pneumonia or exacerbate breathing difficulties, particularly in breeds prone to gastroesophageal issues.

  • Sliding hiatal hernia: This condition reflects displacement of abdominal organs into the thoracic cavity, which can contribute to airway obstruction and respiratory distress.

Brachycephalic Obstructive Airway Disease (BOAS)
Function Grading

  • Grade 0: Normal physiology; no signs of airway obstruction, allowing for unrestricted airflow and normal respiratory function.

  • Grade I: Mild obstruction present; observers may notice mild snoring or stertor, but the animal generally maintains adequate airflow.

  • Grade II: Moderate obstruction; characterized by increased respiratory effort, potential cyanosis during exercise, and visual difficulty breathing.

  • Grade III: Significant obstruction identified; surgical intervention is typically recommended to alleviate symptoms and improve quality of life.

Surgical Considerations

  • A comprehensive examination is advised for dogs diagnosed with high-grade BOAS to determine the most effective surgical interventions.

  • Common surgical procedures include nostril surgery to widen the nasal openings, partial staphylectomy to shorten the soft palate, and excision of everted laryngeal saccules to reduce airway obstruction.

Laryngeal Collapse Staging

  1. Stage 1: Eversion of the laryngeal saccules, which may lead to increased airflow resistance during breathing.

  2. Stage 2: Medial deviation of the cuneiform cartilage or collapse of the aryepiglottic fold, significantly impacting airflow and requiring surgical planning.

  3. Stage 3: Severe condition with medial deviation of the corniculate process of the arytenoid cartilage, necessitating immediate surgical intervention to restore airway patency.

Surgical Techniques

  • Rhinoplasty: Techniques such as wedge-resection or alar fold resection are employed to correct stenotic nostrils and improve airflow. No method is universally superior, but outcomes vary based on individual anatomical needs.

  • Surgery of the Soft Palate: Procedures like partial staphylectomy and palatoplasty (using folded-flap techniques) are commonly utilized to decrease the length and thickness of the soft palate.

  • Tonsillectomy: This procedure may be necessary in conjunction with other surgeries to relieve significant airway obstruction and is often indicated when tonsillar hypertrophy is present.

Idiopathic Acquired Laryngeal Paralysis

  • Clinical signs include: Stridor (abnormal high-pitched sounds), cough, dyspnea (difficulty breathing), changes in bark, and exercise intolerance; these signs necessitate careful observation and evaluation.

  • Diagnosis: Involves identifying characteristic clinical signs, performing laryngoscopy for direct visualization, neurological examinations, and imaging of the thorax to evaluate for underlying conditions.

  • Management: Emergency interventions include providing rest, oxygen support if needed, and potential surgical options (e.g., arytenoid lateralization) to correct the laryngeal dysfunction.

Surgical Management: Arytenoid Lateralization

  • This procedure aims to prevent dynamic collapse of the arytenoid cartilage during breathing, thereby restoring adequate airflow.

  • Post-operative management is critical and includes strict rest, monitoring for complications such as seroma formation, airway obstruction recurrence, and aspiration pneumonia.

Tracheal Collapse

  • Defined as an excessive collapsibility of the trachea during respiration, this condition can present with a characteristic 'goose-honk' cough, notably when excited or after exercise.

  • Management strategies generally consist of medical therapy involving antitussives and bronchodilators, along with surgical interventions (like open ring prosthesis or stenting) depending on the severity of the collapse and clinical symptoms.

Nasal Diseases in Dogs

  • Common nasal conditions seen in dogs include foreign bodies, neoplasms (e.g., nasal polyps and tumors), fungal infections (particularly aspergillosis), and chronic rhinitis.

  • Diagnostic approaches involve advanced imaging techniques such as CT scans, rhinoscopy, and cytological evaluations to determine precise underlying causes.

Chronic Rhinitis in Cats

  • This condition is characterized by persistent inflammation of the nasal passages, which may stem from viral infections (e.g., feline herpesvirus), ultimately leading to destruction of nasal conchae and impairing normal respiratory function.

  • Diagnosis often requires imaging and potential biopsy procedures to definitively identify the underlying pathology and guide appropriate treatment strategies.