Tracheal Collapse

1. Tracheal Collapse Christina Copple, DVM Radiology Resident NCSU CVM-VTH Accession numbers 109894 and 109673

2. Pooh • 11yr old M Yorkshire Terrier • Internal Medicine Service for evaluation elevated liver & kidney enzymes, and cardio consult (hx of ARF due to pyelonephritis and also mitral & tricuspid regurgitation) • Owner reports cough for 3-4 years, in the morning, attempts to cough something up • Recent weight gain

3. Pooh’s Physical Examination • TPR normal • BCS-7/9 = overconditioned • Thoracic auscultation: soft murmur on right side, slightly harsh lung sounds with inspiratory crackles on right and expiratory effort • Hepatomegaly on abdominal palpation http://www.welcometothedoghouse.net/pics/yorkshire_terrier_wallpaper.jpg

4. Pooh’s Diagnostics • BP elevated at 210 • Inflammatory leukogram • Hypercholesterolemia, moderately elevated ALT/ALP • Cardio consult: unchanged left/right atrial enlargement and mitral/tricuspid regurgitation, new- mild right ventricular enlargement and moderate pulmonary hypertension • Endotracheal wash-suggestive of chronic inflammation • Thoracic radiographs

5. Left lateral Accession # 109894 Right lateral

6. VD thorax Accession # 109894

7. Acquired disease of middle-aged Toy and Miniature breeds with unknown cause; prevalence 0.5-2.9% Two types Dorsoventral = most common; often associated with a redundant, flaccid dorsal tracheal membrane Lateral = rare Usually involves cervical region but both cervical & thoracic areas can be involved and may extend into the bronchi No loss of tracheal ring size but rings lose ability to remain firm and become weakened= deficiency in organic matrix of tracheal cartilage Hypocellular Lacking or deficient glycoproteins and glycosaminoglycans, chondroitin sulfate and calcium Tracheal Collapse

8. Associated problems: Chronic coughing-long term airway and/or pulmonary parenchymal disease Obesity and increased mediastinal fat Chronic cardiac disease with tracheal/bronchial compression Also tracheal trauma, denervation of dorsal tracheal membrane, congenital defects Increasing respiratory work dynamic collapse of dorsal tracheal membrane into lumen Results in further irritation and inflammation of mucous membranes, disruption of mucociliary apparatus, increased risk of small airway disease Tracheal Collapse

9. Tracheal Collapse (“Respiratory Distress Syndrome”)-History and Physical Examination • Paroxysmal, chronic cough for long period of time • Cough elicited on tracheal palpation: chronic, harsh, dry, “goose honk” • Toy and miniature breeds: Chihuahuas, Pomeranians, Toy Poodles, Shih Tzus, Lhasa apsos, and Yorkshire Terriers • Obese • Varying degrees of inspiratory or expiratory dyspnea, inspiratory noises, expiratory grunt with abdominal effort • Lung sounds-normal to rattling, stridorous, wheezing • Hepatomegaly-relationship to syndrome unclear

10. Tracheal Collapse-Diagnostics • Radiographs: during both phases or respiration to demonstrate dynamic nature; inspiratory-cervical region collapse, expiratory-thoracic region collapse with unchanged or slightly dilated cervical region • Fluoroscopy-assess severity; may only see collapse during forced expiration of coughing • Tracheoscopy/Bronchoscopy with wash -decreased dorsoventral tracheal diameter and pendulous dorsal tracheal membrane http://i180.photobucket.com/albums/x146/ciethe529/YorkshireTerrier.jpg

11. Tracheal Collapse-Chronic Medical Therapy • Bronchodilators (Aminophylline or Theophylline): reduction in spasm of smaller airways-reduces intrathoracic pressures and thus decreases tendency of larger airways to collapse; improves mucociliary clearance; reduces diaphragmatic fatigue • Beta-agonists (Terbutaline or Albuterol) • Antitussives (Butorphanol) • WEIGHT REDUCTION • No neck collars, remove noxious irritants such as gas, smoke, or dust

12. Tracheal Collapse-Surgical Therapy • Last resort!-does not resolve mainstem or distal bronchial collapse if present • Plication of dorsal tracheal membrane • Placement of external tracheal ring prostheses • Intraluminal stents http://cvm.msu.edu/hospital/services/interventional-radiology/ir-media/Tracheal%20Stent.jpg

13. Thoracic radiographs fundamental to diagnosis-detects tracheal collapse in 60-84% esp. with inspiratory/expiratory views Fluoroscopy-imaging modality of choice for dynamic airway changes Bronchoscopy-when former are inconclusive, evaluate diameter and grade luminal changes Tracheal narrowing = ratio of tracheal diameter:thoracic inlet width <0.2 Thoracic radiographs-first line assessment of bronchiectasis Bronchial wall thickening and alveolar disease Cylindrical (failure to taper peripherally) and saccular (distal bronchi dilated with rounded, cyst-like structures) bronchial wall dilation A Retrospective Study of the Relationship Between Tracheal Collapse and Bronchiectasis in DogsVetRadUS, Vol. 48.3, 2007:199-203

14. Tracheal Collapse and Bronchiectasis cont’dVetRadUS, Vol. 48.3, 2007:199-203 • 60 patients included, all had tracheal collapse (No control group) • 90% small breed dogs • Most commonly affected breed = Yorkshire Terrier • 30% had both tracheal collapse and bronchiectasis; all were cylindrical • Most commonly affected breed = Yorkshire Terrier • Evidence of link between tracheal collapse & bronchiectasis and patients with both conditions should be further evaluated for chronic lower airway disease

15. References • Ettinger, Stephen J. and Edward C. Feldman. Textbook of Veterinary Internal Medicine. 6th ed. Volume 2. Elsevier. St. Louis, MO. 2000:1224-1228. • Marolf, Angela, Margaret Blaik, and Andrew Specht. A Retrospective Study of the Relationship Between Tracheal Collapse and Bronchiectasis in Dogs.Veterinary Radiology & Ultrasound. 48.3, 2007:199-203.

16. Trach Fluoroscopy during coughing episode Accession # 109673