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Hypoplastic Trachea 521

severe deficiency exists, correcting hypomag- but antipyretic drugs (e.g., nonsteroidal but clients should be prepared for frequent
nesemia may resolve the hypoparathyroidism. • Compounded calcitriol formulations have • Treatment must be lifelong with naturally
antiinflammatories) are not.
rechecks.
VetBooks.ir • Glucocorticoids may worsen/precipitate hypo- variable stabilities. It is best to use an occurring hypoparathyroidism. Diseases and Disorders
• Over-the-counter vitamin D supplements
are not appropriate for treatment.
experienced compounding pharmacy and
SUGGESTED READING
calcemia associated with hypoparathyroidism.
to heed the labeled expiration date.
Henderson AK, et al: Hypoparathyroidism: patho-
Technician Tips Client Education physiology and diagnosis. Compend Contin Educ
• Hyperthermia in hypocalcemic patients usually • Appropriate therapy requires repeated Vet 27:270-279, 2005.
results from muscle fasciculations, not true evaluation of serum calcium concentrations. AUTHOR: Patty Lathan, VMD, MS, DACVIM
fever. Cooling measures (e.g., moistening paw Monitoring will become less intensive as EDITOR: Ellen N. Behrend, VMD, PhD, DACVIM
pads, fan/air circulation) may be appropriate, serum calcium concentrations stabilize,

Hypoplastic Trachea Client Education
Sheet

BASIC INFORMATION (e.g., increased lung sounds, fever, lethargy, ○ TD/TI ratio is the ratio of tracheal
tachypnea, increased respiratory effort) diameter (TD) at the level of the thoracic
Definition • Hyperthermia inlet to the thoracic inlet diameter (TI).
Congenital narrowing of the tracheal lumen TI is the distance from the ventral aspect
Etiology and Pathophysiology of the vertebral column at the midpoint
Epidemiology • Trachea develops with rigid cartilaginous of the first rib to the closest point on the
SPECIES, AGE, SEX rings, ring ends apposed/overlapped, and inner surface of the manubrium. For dogs
Dogs < 1 year old but persists for life; 2 : 1 dorsal membrane narrow/absent, narrowing older than 6 months, radiographic TD/
males : females; not reported in cats the tracheal lumen. TI < 0.18 for breeds other than bulldogs
• Narrowed tracheal lumen increases linear and < 0.14-0.15 for bulldogs is diagnostic
GENETICS, BREED PREDISPOSITION air velocity, tracheal resistance, and work for tracheal hypoplasia.
• Of reported dogs, 55% are bulldogs and of respiration. ○ CT measurements average 19% larger than
15% are Boston terriers. tracheal measurements.
• Reported as a recessive trait in Husky-mix DIAGNOSIS ○ Persian cats have the same tracheal
puppies with blue eyes and partially white diameter as nonbrachycephalic cats.
faces Diagnostic Overview ○ Diameter measured with tracheoscopy
Diagnosis is based on comparison of tracheal does not correlate with CT or radiography.
ASSOCIATED DISORDERS diameter to thoracic inlet diameter or by • Tracheoscopy: luminal narrowing, mucosal
• Brachycephalic airway syndrome (BAS): tracheoscopic evaluation. Normal tracheal swelling, overlapping tracheal cartilage rings,
○ Hypoplastic trachea seen in 13% dogs diameter is smaller in bulldogs than in other narrow dorsal membrane
with BAS breeds. • Airway lavage in dogs with bronchopneu-
Elongated soft palate in 43% of dogs monia for cytology plus bacterial culture and
■
with hypoplastic trachea, stenotic nares Differential Diagnosis sensitivity (pp. 1073 and 1074)
in 22% • Elongated soft palate
• Other congenital anomalies (pulmonic or • Everted laryngeal saccules
aortic stenosis, megaesophagus) or respiratory • Stenotic nares
abnormalities (bronchopneumonia, laryngeal • Laryngeal paralysis or collapse
paralysis, everted laryngeal saccules, laryngeal • Tracheal collapse
collapse) may be present. • Any cause of bronchopneumonia or
tracheobronchitis
Clinical Presentation • Ciliary dyskinesia
HISTORY, CHIEF COMPLAINT
• Incidental finding in ≈10% of affected Initial Database
dogs • CBC: inflammatory leukogram ± left shift
• Recurrent respiratory infections poorly possible if bronchopneumonia present
responsive to treatment • Serum biochemistry panel and urinalysis:
• Clinical signs associated with concurrent usually normal
brachycephalic syndrome such as stertor, • Thoracic radiographs
stridor, exercise intolerance, lethargy, cough- ○ Diffusely narrowed tracheal lumen
ing, gagging, regurgitation, syncope ○ Bronchopneumonia in approximately 8%
of cases at the time they present for care
PHYSICAL EXAM FINDINGS
• Physical exam can be unremarkable. Advanced or Confirmatory Testing HYPOPLASTIC TRACHEA Hypoplastic trachea in
• Respiratory signs (e.g., dyspnea [pre- • Decreased tracheal diameter on lateral a 4-month-old pug with seizures and stenotic nares.
dominantly inspiratory], cough, inspiratory thoracic radiographs, CT, or tracheoscopy On necropsy, the puppy’s trachea had complete
stridor if laryngeal abnormalities, stertor if ○ On radiographs and CT, diffuse sym- (solid) cartilaginous rings and no dorsal longitudinal
elongated soft palate), bronchopneumonia metrical (round) narrowing membrane.

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