Objective—To validate the use of noninvasive pulmonary function testing in sedated and nonsedated llamas and establish reference range parameters of respiratory mechanical function.
Animals—10 healthy adult llamas.
Procedures—Pulmonary function testing in llamas included the following: measurement of functional residual capacity (FRC) via helium dilution, respiratory inductance plethysmography (RIP) to assess breathing pattern and flow limitations, esophageal-balloon pneumotachography, and a monofrequency forced oscillatory technique (FOT; 1 to 7 Hz) before and after IM administration of xylazine (0.2 mg/kg).
Results—The following mean ± SD measurements of respiratory function were obtained in nonsedated llamas: FRC (5.60 ± 1.24 L), tidal volume (1.03 ± 0.3 L), dynamic compliance (0.83 ± 0.4 L/cm H2O), pulmonary resistance (RL; 1.42 ± 0.54 cm H2O/L/s), and respiratory system resistance (2.4 ± 0.9, 2.3 ± 0.7, 2.2 ± 0.6, 2.7 ± 0.7, and 2.5 ± 0.5 cm H2O/L/s at 1, 2, 3, 5, and 7 Hz, respectively) by use of FOT. Measurements of flow limitations via RIP were comparable to other species. Sedation with xylazine induced significant increases in RL and maximum change in transpulmonary pressure. Following sedation, a mean 127% increase in RL and mean 116% increase in respiratory system resistance were observed across 1 to 7 Hz. The magnitude of change in respiratory system resistance increased with decreasing impulse frequency, suggesting bronchoconstriction.
Conclusions and Clinical Relevance—Noninvasive pulmonary function testing is well tolerated in untrained unsedated llamas. These techniques have clinical applications in the diagnosis and treatment of respiratory tract disease, although testing should not be performed after sedation with xylazine.
Objective—To evaluate respiratory mechanical function and bronchoalveolar lavage (BAL) cytologic results in healthy alpacas.
Animals—16 client-owned adult alpacas.
Procedures—Measurements of pulmonary function were performed, including functional residual capacity (FRC) via helium dilution, respiratory system resistance via forced oscillatory technique (FOT), and assessment of breathing pattern by use of respiratory inductive plethysmography (RIP) in standing and sternally recumbent alpacas. Bronchoalveolar lavage was performed orotracheally during short-term anesthesia.
Results—Mean ± SD measurements of respiratory function were obtained in standing alpacas for FRC (3.19 ± 0.53 L), tidal volume (0.8 ± 0.13 L), and respiratory system resistance at 1 Hz (2.70 ± 0.88 cm H2O/L/s), 2 Hz (2.98 ± 0.70 cm H2O/L/s), 3 Hz (3.14 ± 0.77 cm H2O/L/s), 5 Hz (3.45 ± 0.91 cm H2O/L/s), and 7 Hz (3.84 ± 0.93 cm H2O/L/s). Mean phase angle, as a measurement of thoracoabdominal asynchrony, was 19.59 ± 10.06°, and mean difference between nasal and plethysmographic flow measurements was 0.18 ± 0.07 L/s. Tidal volume, peak inspiratory flow, and peak expiratory flow were significantly higher in sternally recumbent alpacas than in standing alpacas. Cytologic examination of BAL fluid revealed 58.52 ± 12.36% alveolar macrophages, 30.53 ± 13.78% lymphocytes, 10.95 ± 9.29% neutrophils, 0% mast cells, and several ciliated epithelial cells.
Conclusions and Clinical Relevance—Pulmonary function testing was tolerated well in nonsedated untrained alpacas. Bronchoalveolar lavage in alpacas yielded samples with adequate cellularity that had a greater abundance of neutrophils than has been reported in horses.
Objective—To evaluate the effects of obesity on pulmonary function in healthy adult dogs.
Animals—36 Retrievers without cardiopulmonary disease.
Procedures—Dogs were assigned to 1 of 3 groups on the basis of body condition score (1 through 9): nonobese (score, 4.5 to 5.5), moderately obese (score, 6.0 to 6.5), and markedly obese (score, 7.0 to 9.0). Pulmonary function tests performed in conscious dogs included spirometry and measurement of inspiratory and expiratory airway resistance (Raw) and specific Raw (sRaw) during normal breathing and during hyperpnea via head-out whole-body plethysmography. Functional residual capacity (FRC; measured by use of helium dilution), diffusion capacity of lungs for carbon monoxide (DLCO), and arterial blood gas variables (PaO2, PaCO2, and alveolar-arterial gradient) were assessed.
Results—During normal breathing, body condition score did not influence airway function, DLCO, or arterial blood gas variables. During hyperpnea, expiratory sRaw was significantly greater in markedly obese dogs than nonobese dogs and Raw was significantly greater in markedly obese dogs, compared with nonobese and moderately obese dogs. Although not significantly different, markedly obese dogs had a somewhat lower FRC, compared with other dogs.
Conclusions and Clinical Relevance—In dogs, obesity appeared to cause airflow limitation during the expiratory phase of breathing, but this was only evident during hyperpnea. This suggests that flow limitation is dynamic and likely occurs in the distal (rather than proximal) portions of the airways. Further studies are warranted to localize the flow-limited segment and understand whether obesity is linked to exercise intolerance via airway dys-function in dogs.