The diffusing capacity for carbon monoxide (DLCO) and the functional residual capacity (FRC) of the lung were measured in 5 healthy Thoroughbreds before and after instillation of autologous blood into their lungs, in an attempt to develop a method to quantitate extravascular blood in the lungs of horses with exercise-induced pulmonary hemorrhage. Mean (+/- SD) baseline values of DLCO and FRC were 333.8 +/- 61.9 ml/min/mm of Hg and 21.464 +/- 4.156 L, respectively. Blood instillation resulted in decreases in DLCO and FRC. The paradoxic decrease in DLCO (we were expecting to find an increase owing to blood in the airspaces, as has been reported in people) appears to be associated with the bronchoscopic procedure and with presence of blood in the airways. We concluded that rebreathing DLCO measurements were not effective for detecting blood introduced bronchoscopically into the lungs of horses.

Static lung compliance, static lung volumes, and transfer factor for carbon monoxide were measured in 12 anesthetized adult Texel ewes seropositive for maedi-visna virus (MVV) and in 11 breed-, sex-, and age-matched seronegative controls. Median static lung compliance in MVV-infected sheep (1.24 L.kPa-1; range, 0.27 to 2,20 L.kPa-1) was not significantly different from that in controls (1.58 L.kPa-1; range, 0.82 to 2.08 L.kPa-1). Median body weight of MVV-infected sheep (56 kg; range, 40 to 75 kg) was significantly (P < 0.05) less than that of controls (65 kg; range, 53 to 87 kg). Median effective alveolar lung volume in MVV-infected sheep (3.36 L; range, 1.44 to 4.52 L) was significantly (P < 0.01) less than that in controls (4.12 L; range, 3.75 to 4.90 L). Median effective end expiratory lung volume in MVV-infected sheep (1.20 L; range, 0.56 to 1.99 L) was significantly (P < 0.001) less than that of controls (1.98 L; range: 1.76 to 2.78 L). Median lung volumes expressed per unit of body weight did not differ significantly between the groups. Median single-breath transfer factor for carbon monoxide in MVV-infected sheep (7.89 mmol-min-1.kPa-1; range, 3.45 to 12.74 mmol.min-1.kPa-1) was significantly (P < 0.001) less than that in controls (14.10 mmol.min-1-kPa-1; range, 10.02 to 18.30 mmol.min-1-kPa-1). Median transfer factor expressed per liter of alveolar volume in MVV-infected sheep (2.44 mmol.min-1-kPa-1.L-1; range, 1.28 to 3.72 mmol.min-1-kPa-1.L-1) gm significantly (P < 0.05) less than that in controls (3.22 mmol.min-1-kPa-1.L-1; range, 2.47 to 3.74 mmol.min-1-kPa-1.L-1). These findings indicate that static lung volumes and transfer factor for carbon monoxide are significantly decreased in adult sheep naturally infected with MVV.

OBJECTIVE To assess changes in biochemical and biophysical properties of canine RBCs during cold (1° to 6°C) storage in a licensed RBC additive solution (the RBC preservation solution designated AS-1) supplemented with ascorbic acid. SAMPLE Blood samples from 7 neutered male Greyhounds; all dogs had negative results when tested for dog erythrocyte antigen 1.1. PROCEDURES Blood was collected into citrate-phosphate-dextrose and stored in AS-1. Stored RBCs were supplemented with 7.1mM ascorbic acid or with saline (0.9% NaCl) solution (control samples). Several biochemical and biophysical properties of RBCs were measured, including percentage hemolysis, oxygen-hemoglobin equilibrium, and the kinetic rate constants for O2 dissociation, carbon monoxide association, and nitric oxide dioxygenation. RESULTS Greyhound RBCs stored in AS-1 supplemented with ascorbic acid did not have significantly decreased hemolysis, compared with results for the control samples, during the storage period. CONCLUSIONS AND CLINICAL RELEVANCE In this study, ascorbic acid did not reduce hemolysis during storage. Several changes in stored canine RBCs were identified as part of the hypothermic storage lesion.

A rebreathing method for measurement of pulmonary diffusing capacity for carbon monoxide (DL(CO)) and functional residual capacity (FRC) was evaluated in conscious horses. Horses were manually ventilated through an endotracheal tube, using a custom-made syringe filled with a gas mixture containing 18-carbon monoxide (18CO) and helium (He). The 18CO and He concentrations were continuously monitored by use of a mass spectrometer connected to the rebreathing circuit. Values for DL(CO), and FRC were calculated from changes in the concentration of these 2 gases. In 11 Thoroughbreds, mean (+/- SD) DL(CO) was 330.3 +/- 56.9 ml.min-1.mm of Hg-1, and FRC was 20.21 +/- 3.35 L. Body weight normalization yielded mean (+/- SD) values of 0.652 +/- 0.114 ml.min-1.mm of Hg-1.kg-1 for DL(CO), and 39.9 +/- 6.4 ml.kg-1 for FRC.