Effects of isoflurane on the CBC in ferrets were studied. There was rapid decrease in all hematologic variables after induction of anesthesia. Percentage reductions in indices of the erythron (hematocrit, RBC count, hemoglobin concentration) exceeded those of plasma protein concentration and WBC count at the first postinduction time point. There was little additional decrease in these variables for the duration of anesthesia. The values had partially recovered to preanesthetic baseline at 45 minutes after anesthesia. Although these alterations appear to be well tolerated in healthy ferrets, care should be exercised when subjecting anemic, geriatric, or debilitated ferrets to isoflurane-induced anesthesia.

The steady-state response characteristics of a pulse oximeter were evaluated on intestinal segments of seven clinically normal halothane-anesthetized horses. Arterial oxygen tension > 200 mm of Hg, end tidal carbon dioxide from 30 to 35 mm of Hg, and systemic mean arterial pressure > 70 mm of Hg were maintained throughout the recording periods. Values for percentage of pulse oximeter oxygen saturation, pulsatile blood flow, and percentage of signal strength were recorded from jejunum, ileum, cecum, left ventral colon, left dorsal colon, and descending colon. Probe placement on intestinal segments was recorded as over or not over visible subserosal or transmural vessels. There was no significant difference between median values on the basis of vessel codes for pulse oximeter oxygen saturations, pulsatile flow, and signal strength. Median values recorded for pulse oximeter oxygen saturation were 93% from jejunum and ileum and 95% from cecum, left ventral colon, left dorsal colon, and descending colon; median values for pulsatile flow were 576 from jejunum, 560 from ileum, 560 from cecum, 574 from left ventral colon, 578 from left dorsal colon, and 560 from descending colon; median values for signal strength were 50% from jejunum, 67.5% from ileum, 60% from cecum, 75% from left ventral colon, 50% from left dorsal colon, and 52.5% from descending colon. Median values obtained from each anatomic location were not significantly different for pulsatile flow or signal strength. Median pulse oximetry oxygen values recorded from jejunum and ileum were significantly lower than values obtained from other intestinal segments. When calculated arterial oxygen saturation was compared with oxygen saturation determined by the pulse oximeter, pulse oximeter oxygen saturation was consistently lower by 6.7% (jejunum and ileum) and 4.7% (cecum, left ventral colon, left dorsal colon, and descending colon). Equine and human absorption spectra were generated and compared for reduced hemoglobin and oxyhemoglobin at wavelengths of 600 nm (red) to 950 nm (infrared). Extinction coefficients calculated at wavelengths used by the pulse oximeter (660 nm and 940 nm) were nearly identical. The pulse oximeter is a self-calibrating instrument that displays oxygen saturation, heart rate, plethysmographic waveform, and signal strength indicator. Probe application was rapid and easy. Response time for the appearance of a plethysmographic waveform ranged from 5 to 25 seconds.

OBJECTIVE To evaluate the repeatability and accuracy of fingertip pulse oximeters (FPO) for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate (PR) in anesthetized dogs breathing 100% O2. ANIMALS 29 healthy client-owned anesthetized dogs undergoing various surgical procedures. PROCEDURES In randomized order, each of 7 FPOs or a reference pulse oximeter (PO) was applied to the tongue of each intubated anesthetized dog breathing 100% O2. Duplicate measurements of oxygen saturation (Spo2) and PR were obtained within 60 seconds of applying an FPO or PO. A nonparametric version of Bland-Altman analysis was used. Coefficient of repeatability was the interval between the 5th and 95th percentiles of the differences between duplicate measurements. Bias was the median difference, and the limits of agreement were the 5th and 95th percentiles of the differences between each FPO and the PO. Acceptable values for the coefficient of repeatability of Spo2 were ≤ 6%. Agreements were accepted if the limits of agreement had an absolute difference of ≤ ± 3% in Spo2 and relative difference of ≤ ± 10% in PR. RESULTS Coefficient of repeatability for Spo2 was acceptable for 5 FPOs, but the limits of agreement for Spo2 were unacceptable for all FPOs. The limits of agreement for PR were acceptable for 2 FPOs. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that some FPOs may be suitable for accurately monitoring PRs of healthy anesthetized dogs breathing 100% O2, but mild underestimation of Spo2 was common.

Concentrations of 64% to 70% nitrous oxide (N(2)O) provide intra-operative analgesia. Clinically, pulse oximeter estimation (SpO(2)) of oxygen (O(2)) hemoglobin saturation (SaO(2)) was observed to decrease with N2O. Absorption atelectasis from breathing O2 was thought to decrease arterial partial pressure of O2 (PaO(2)) below 70 mmHg and reduce SaO(2) and SpO(2) when N(2)O was used. Administering N(2)O from the beginning of the anesthesia might prevent atelectasis development and low PaO(2).The study was done in 2 parts (P, 0.05). In Part 1, isoflurane-anesthetized dogs undergoing ovariohysterectomy (n = 15 each group) breathed N(2)O from anesthesia start (N(2)O early) or 1 hour later (N2Olate). SpO(2), CO-oximetry values, and PaO(2) were compared to dogs breathing O(2) throughout anesthesia (control). Timing of N(2)O introduction did not affect PaO(2) (lowest = 94 mmHg), SaO(2), or SpO(2). With N(2)O, the lowest SpO(2) value was 91% and corresponded to a PaO2 of 151 mmHg. Carboxyhemoglobin increased (highest = 2.7%) and SaO(2) decreased with N2O (lowest = 96.7%). In Part 2, to replicate findings, 10 isoflurane-anesthetized dogs breathed N(2)O, then O(2). With N2O, SaO2 did not decrease, but carboxyhemoglobin increased and returned to baseline once N2O was discontinued. The dog with the highest carboxyhemoglobin (2%) had an SaO(2) of 96.8% (PaO(2) = 93 mmHg). Carboxyhemoglobin and SaO(2) changes were not clinically significant. Pulse oximetry did not reliably estimate SaO(2) but N(2)O was not always a factor.

OBJECTIVE To determine whether passage of whole blood through a microaggregate filter by use of a syringe pump would damage canine erythrocytes. SAMPLE Blood samples obtained from 8 healthy client-owned dogs. PROCEDURES Whole blood was passed through a standard microaggregate filter by use of a syringe pump at 3 standard administration rates (12.5, 25, and 50 mL/h). Prefilter and postfilter blood samples were collected at the beginning and end of a simulated transfusion. Variables measured at each time point included erythrocyte osmotic fragility, mean corpuscular fragility, RBC count, hemoglobin concentration, RBC distribution width, and RBC morphology. In-line pressure when blood passed through the microaggregate filter was measured continuously throughout the simulated transfusion. After the simulated transfusion was completed, filters were visually analyzed by use of scanning electron microscopy. RESULTS Regardless of administration rate, there was no significant difference in mean corpuscular fragility, RBC count, hemoglobin concentration, or RBC distribution width between prefilter and postfilter samples. Additionally, there were no differences in in-line pressure during the simulated transfusion among administration rates. Echinocytes were the erythrocyte morphological abnormality most commonly observed at the end of the transfusion at administration rates of 12.5 and 25 mL/h. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that regardless of the administration rate, the microaggregate filter did not alter fragility of canine RBCs, but may have altered the morphology. It appeared that the microaggregate filter would not contribute to substantial RBC damage for transfusions performed with a syringe pump.

Pregnancy in many mammals, including mares, is associated with physiological changes that are reflected in hematological and biochemical profiles. Understanding those physiological changes and differentiating them from pathological changes is imperative for providing care and medical therapy in pregnant mares. Our objective was to compare normal hematological and biochemical profiles in healthy non-pregnant as well as healthy pregnant mares during the 1st and 2nd trimesters of pregnancy. Blood was collected by jugular venipuncture into ethylenediaminetetraacetic acid and serum tubes. Whole blood was analyzed using an ADVIA 120 hematologic analyzer and serum was analyzed using a Beckman Coulter AU5400. Statistical differences were detected using analysis of variance (ANOVA) and independent Student's t-test; P < 0.05 was considered significant. Results demonstrated higher red blood cell counts and hemoglobin concentrations and lower eosinophil counts (P < 0.001) in non-pregnant mares (n = 32) compared with pregnant mares at both 1st (n = 25) and 2nd (n = 17) trimesters. Biochemical analysis showed a significant decrease (P < 0.001) in albumin and blood urea nitrogen (P < 0.001) in the 2nd trimester and higher potassium levels (P = 0.03) in pregnant mares. Understanding such physiological changes is imperative to providing optimum care and medical treatment in mares. These data will assist clinicians to better evaluate and treat pregnant mares.

OBJECTIVE To compare bronchoalveolar lavage (BAL) accomplished by use of a bronchoscopic (B-BAL) and a nonbronchoscopic (NB-BAL) technique in healthy cats. ANIMALS 12 healthy cats. PROCEDURES Two BALs were performed in a randomized order 2 weeks apart in each cat. Cats were anesthetized, and a 2.9-mm fiberoptic bronchoscope (B-BAL) or 8F red rubber catheter (NB-BAL) was wedged in a bronchus. Two 5-mL aliquots of saline (0.9% NaCl) solution were infused into the left and right caudal lung fields and aspirated manually with a 20-mL syringe. Proportion of BAL fluid (BALF) retrieved, depth of wedging, and anesthetic complications were recorded. Total nucleated cell count, differential cell count, and semiquantitative scores of cytologic slide quality were determined for all BALF samples. Results were compared with ANOVAs and Wilcoxon signed rank tests. RESULTS Proportion of retrieved BALF and depth of wedging were significantly greater for B-BAL than NB-BAL. Differential cell counts and cytologic slide quality did not differ significantly between techniques. Complications included transient hemoglobin desaturation (24/24 [100%] BALs) and prolonged anesthetic recovery time (4/24 [17%] BALs). Anesthetic recovery scores did not differ significantly between techniques. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that NB-BAL was noninferior to B-BAL with regard to ease of performance, anesthetic variables, and cytologic slide quality for cats without clinical respiratory tract disease.

OBJECTIVE To assess multiple central venous and arterial blood variables that alone or in conjunction with one another reflect global oxygenation status in healthy neonatal foals. ANIMALS 11 healthy neonatal foals. PROCEDURES Central venous and arterial blood samples were collected from healthy neonatal foals at 12, 24, 36, 48, 72, and 96 hours after birth. Variables measured from central venous and arterial blood samples included oxygen saturation of hemoglobin, partial pressure of oxygen, lactate concentration, partial pressure of carbon dioxide, and pH. Calculated variables included venous-to-arterial carbon dioxide gap, estimated oxygen extraction ratio, ratio of partial pressure of oxygen in arterial blood to the fraction of inspired oxygen, bicarbonate concentration, base excess, and blood oxygen content. RESULTS Significant differences between arterial and central venous blood obtained from neonatal foals were detected for several variables, particularly partial pressure of oxygen, oxygen saturation of hemoglobin, and oxygen content. In addition, the partial pressure of carbon dioxide in central venous blood samples was significantly higher than the value for corresponding arterial blood samples. Several temporal differences were detected for other variables. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study provided information about several variables that reflect global oxygenation in healthy neonatal foals. Values for these variables in healthy foals can allow for comparison with values for critically ill foals in future studies. Comparison of these variables between healthy and ill foals may aid in treatment decisions and prognosis of clinical outcome for critically ill foals.

OBJECTIVE To determine effects of IV transfusion with fresh (3-day-old) or stored (35-day-old) autologous erythrocyte concentrate on serum labile iron concentration, iron-binding capacity, and protein interaction with iron in dogs. ANIMALS 10 random-source healthy dogs. PROCEDURES Dogs were randomly assigned to receive autologous erythrocyte concentrate stored for 3 days (n = 5) or 35 days (5). One unit of whole blood was collected from each dog, and erythrocyte concentrates were prepared and stored as assigned. After erythrocyte storage, IV transfusion was performed, with dogs receiving their own erythrocyte concentrate. Blood samples were collected from each dog before and 5, 9, 24, 48, and 72 hours after transfusion. Serum was harvested for measurement of total iron, labile iron, transferrin, ferritin, hemoglobin, and haptoglobin concentrations. RESULTS For dogs that received fresh erythrocytes, serum concentrations of the various analytes largely remained unchanged after transfusion. For dogs that received stored erythrocytes, serum concentrations of total iron, labile iron, hemoglobin, and ferritin increased markedly and serum concentrations of transferrin and haptoglobin decreased after transfusion. CONCLUSIONS AND CLINICAL RELEVANCE Transfusion with autologous erythrocyte concentrate stored for 35 days resulted in evidence of intravascular hemolysis in healthy dogs. The associated marked increases in circulating concentrations of free iron and hemoglobin have the potential to adversely affect transfusion recipients.

The objective of this study was to determine the effects of the administration of a high volume of isotonic crystalloid at a rapid rate on cardiovascular function in normovolemic, isoflurane-anesthetized dogs during induced hypotension. Using a prospective study, 6 adult dogs were induced to general anesthesia and cardiovascular and hematological values were measured while the dogs were maintained at 3 hemodynamic states: first during light anesthesia with 1.3% end-tidal isoflurane (ETI); then during a hypotensive state induced by deep anesthesia with 3% ETI for 45 min while administered 1 mL/kg body weight (BW) per minute of isotonic fluids; and then decreased to 1.6% ETI while receiving 1 mL/kg BW per minute of fluids for 15 min. End-tidal isoflurane (ETI) at 3.0 ± 0.2% decreased arterial blood pressure (ABP), cardiac index (CI), and stroke volume index (SVI), and increased stroke volume variation (SVV) and central venous pressure (CVP). Fluid administration during 3% ETI decreased only SVV and systemic vascular resistance index (SVRI), while CVP increased progressively. Decreasing ETI to 1.6 ± 0.1% returned ABP and SVI to baseline (ETI 1.3 ± 0.1%), while CI and heart rate increased and SVV decreased. There was significant progressive clinical hemodilution of hemoglobin (Hb), packed cell volume (PCV), total protein (TP), colloid osmotic pressure (COP), arterial oxygen content (CaO2), and central-venous oxygen content (CcvO2). High-volume, rapid-rate administration of an isotonic crystalloid was ineffective in counteracting isoflurane-induced hypotension in normovolemic dogs at a deep plane of anesthesia. Cardiovascular function improved only when anesthetic depth was reduced. Excessive hemodilution and its adverse consequences should be considered when a high volume of crystalloid is administered at a rapid rate.