This chapter describes the diagnostic value of pulse oximetry to measure the oxygen that is bound to haemoglobin in cats and dogs.

This prospective study evaluated variation in the diameter of the caudal vena cava (DCdVC) as a marker of change in intravascular volume before and after blood donation in greyhound dogs. A preliminary study determined that the DCdVC increased with body weight. Nine greyhound blood donors had ultrasonographic images acquired of the maximum and minimum DCdVCs in transverse and sagittal orientations and sagittal aortic diameter (AoD) before and after blood donation. The collapsibility index = [(maximal mean transverse DCdVC - minimal mean transverse DCdVC)/maximal mean transverse DCdVC] and transverse DCdVC:AoD ratio were calculated for each dog. In the greyhounds, the changes in mean minimal and maximal transverse DCdVC (0.69 and 0.84 mm, respectively) and sagittal mean maximal DCdVC (0.9 mm) and collapsibility index (0.018) were significantly different (P < 0.05) before and after blood donation. While statistically significant, the magnitude of DCdVC change found in this limited number of greyhound dogs with 8% intravascular volume loss during blood donation was small. This magnitude of change is likely indistinguishable in clinical patients.

OBJECTIVE:To determine the risk of bacterial growth in single use 50% dextrose vials punctured multiple times and stored in various hospital environments.MATERIALS AND METHODS:Three groups of three 50% dextrose vials were stored in our hospital intensive care unit at either ambient light or in a darkened drawer at room temperature or refrigerated at 4°C. One vial in each group was punctured either once, once weekly or once daily for 28 days and samples taken for bacterial culture every 7 days until completion of the project. A fourth group of three vials were inoculated with several species of bacteria and stored in our microbiology laboratory under the environmental conditions described above with cultures performed every 7 days for 28 days. In addition, the water activity of 50% dextrose was determined using commercial laboratory equipment.RESULTS:Scant growth of Escherichia coli and Enterobacter agglomerans was detected in cultures performed on day 7, but not subsequent time points, from the inoculated refrigerated vials. The vial punctured once daily for 28 days and stored under refrigerated conditions showed growth of Bacillus subtilis on day 28. All remaining bottles had no bacterial growth at any time point or environmental condition. The water activity of 50% dextrose was 093 at 24°C and 092 at 4°C.CLINICAL SIGNIFICANCE:Bacterial growth in 50% dextrose vials was uncommon even when inoculated with pathogens. Bacterial growth only occurred in refrigerated storage conditions. The water activity of 50% dextrose is not low enough to inhibit all bacterial and fungal growth.