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 measure the effects of tidal volume, ventilatory frequency, and oxygen insufflation flow on the fraction of inspired oxygen in cadaveric horse heads attached to a lung model. Sample-8 heads of equine cadavers. Procedures-Each cadaveric horse head was intubated with a nasotracheal tube that extended into the proximal portion of the trachea. Oxygen was delivered through an oxygen catheter contained within and extending to the tip of the nasotracheal tube. The trachea was connected to the lung model by use of a spiral-wound hose with a sampling adaptor. Eight treatment combinations involving 2 tidal volumes (5 and 8 L), 2 ventilatory frequencies (6 and 12 mechanical breathes/min), and 2 insufflation rates (10 and 15 L/min) were applied to each head. Hand-drawn inspired gas samples were collected and analyzed for oxygen concentrations. Results-The fraction of inspired oxygen (measured at mid trachea) ranged from 26.8% to 39.4%. Fraction of inspired oxygen was significantly higher with a smaller tidal volume, lower ventilatory frequency, and higher insufflation rate. Conclusions and Clinical Relevance-In the study model, measured fraction of inspired oxygen varied with ventilatory pattern as well as oxygen insufflation rate. Clinically, this information could be beneficial for interpretation of data regarding arterial blood gases and hemoglobin saturation and in making appropriate oxygen insufflation decisions for anesthetized horses that are breathing room air.

Objective: To compare mitochondrial complex I and complex IV activity in myocardial mitochondria of clinically normal dogs, clinically normal dogs exposed to inhalation anesthesia, and dogs affected with dilated cardiomyopathy. Sample: Myocardial samples obtained from 21 euthanized dogs (6 clinically normal [control] dogs, 5 clinically normal dogs subjected to inhalation anesthesia with isoflurane prior to euthanasia, 5 dogs with juvenile-onset dilated cardiomyopathy, and 5 dogs with adult-onset dilated cardiomyopathy). Procedures: Activity of mitochondrial complex I and complex IV was assayed spectrophotometrically in isolated mitochondria from left ventricular tissue obtained from the 4 groups of dogs. Results: Activity of complex I and complex IV was significantly decreased in anesthetized dogs, compared with activities in the control dogs and dogs with juvenile-onset or adult-onset dilated cardiomyopathy. Conclusions and Clinical Relevance: Inhalation anesthesia disrupted the electron transport chain in the dogs, which potentially led to an outburst of reactive oxygen species that caused mitochondrial dysfunction. Inhalation anesthesia depressed mitochondrial function in dogs, similar to results reported in other species. This effect is important to consider when anesthetizing animals with myocardial disease and suggested that antioxidant treatments may be beneficial in some animals. Additionally, this effect should be considered when designing studies in which mitochondrial enzyme activity will be measured. Additional studies that include a larger number of animals are warranted.

Objective: To investigate the effects of the concurrent administration of 70% N2O on the minimum alveolar concentration (MAC) for sevoflurane in dogs, the MAC derivative that blocks motor movement (MAC(NM)), and the MAC derivative that blocks autonomic responses (MAC(BAR)). Animals: 7 adult sexually intact male mixed-breed dogs. Procedures: For each dog, anesthesia was induced with sevoflurane delivered via a face mask. Initially, the baseline MAC, MAC(NM), and MAC(BAR) for sevoflurane were determined by use of a noxious stimulus (50 V, 50 Hz, and 10 milliseconds) applied subcutaneously over a midulnar region. Nitrous oxide (70%) was added to the breathing circuit, and MAC, MAC(NM), and MAC(BAR) were determined again. Percentage changes from the respective baseline concentrations for MAC, MAC(NM)’ and MAC(BAR) were calculated after the administration of N2O. Results: Baseline median values for the MAC, MAC(NM), and MAC(BAR) for sevoflurane were 1.75%, 2.00%, and 2.50%, respectively. Addition of 70% N2O significantly decreased MAC, MAC(NM), and MAC(BAR) by 24.4%, 25.0%, and 35.2%, respectively, and these values did not differ significantly from each other. Conclusions and Clinical Relevance: Supplementation with 70% N2O caused a clinically important and significant decrease in the MAC, MAC(NM)’ and MAC(BAR) for sevoflurane in dogs.

Objective: To characterize clinical and behavioral changes in calves following inoculation with Mycoplasma bovis and evaluate relationships between those changes and pulmonary disease. Animals: 22 healthy Holstein steers. Procedures: 20 calves were inoculated intranasally with < 10(8) CFU or > 10(9) CFU of M bovis. Calves were assigned a clinical illness score (CIS) on a scale of 1 through 4 twice daily on the basis of severity of cough, labored breathing, and lethargy. For each calf, distance traveled and time spent near the waterer, feed bunk, or shelter were determined via a remote location monitoring device. Calves were euthanized and necropsied 22 days after inoculation. Results: 13 calves became clinically ill after challenge inoculation; 3 calves were euthanized within 20 days. Among all calves, consolidation was evident in 0% to 79.9% of the lungs; extent of lung consolidation did not differ between the challenge dose groups. Distance traveled and percentages of time spent in proximity to the feed bunk and shelter were associated with CIS; calves with more severe disease traveled less distance and spent less time at the feed bunk and more time in the shelter. Distance traveled by calves was negatively associated with extent of lung consolidation (< or ≥ 10% of lungs affected); this effect was modified by trial day. Conclusions and Clinical Relevance: Following inoculation with M bovis, calf behavior patterns were associated with both CIS and severity of pulmonary disease. Use of behavior monitoring systems may aid in recognition of respiratory tract disease in calves.