OBJECTIVE To compare effectiveness of glycerol, dimethyl sulfoxide (DMSO), and hydroxyethyl starch (HES) solutions for cryopreservation of avian RBCs. SAMPLE RBCs from 12 healthy Ameraucana hens (Gallus gallus domesticus). PROCEDURES RBCs were stored in 20% (wt/vol) glycerol, 10% (wt/vol) DMSO freezing medium, or various concentrations of HES solution (7.5%, 11.5%, and 20% [wt/vol]) and frozen for 2 months in liquid nitrogen. Cells were then thawed and evaluated by use of cell recovery and saline stability tests, cell staining (7-aminoactinomycin D and annexin V) and flow cytometry, and scanning electron microscopy. RESULTS Percentage of RBCs recovered was highest for 20% glycerol solution (mean ± SE, 99.71 ± 0.04%) and did not differ significantly from the value for 7.5% HES solution (99.57 ± 0.04%). Mean saline stability of RBCs was highest for 10% DMSO (96.11 ± 0.25%) and did not differ significantly from the value for 20% HES solution (95.74 ± 0.25%). Percentages of cells with 7-aminoactinomycin D staining but without annexin V staining (indicating necrosis or late apoptosis) were lowest for 10% DMSO freezing medium (3%) and 20% glycerol solution (1%) and highest for all HES concentrations (60% to 80%). Scanning electron microscopy revealed severe membrane changes in RBCs cryopreserved in 20% HES solution, compared with membrane appearance in freshly harvested RBCs and RBCs cryopreserved in 10% DMSO freezing medium. CONCLUSIONS AND CLINICAL RELEVANCE Cryopreservation of avian RBCs with HES solution, regardless of HES concentration, resulted in greater degrees of apoptosis and cell death than did cryopreservation with other media. Transfusion with RBCs cryopreserved in HES solution may result in posttransfusion hemolysis in birds.

OBJECTIVE To investigate values of spectral indices for use in predicting responses in dogs during determination of minimum alveolar concentration (MAC) of sevoflurane. ANIMALS 15 healthy German Shepherd Dogs. PROCEDURES Sevoflurane MAC was determined by use of tail clamping. Entropy indices consisting of response entropy and state entropy were recorded during MAC determination. Optimal cutoff points of response entropy and state entropy for use in predicting responses to tail clamping were analyzed with multiple logistic regression. RESULTS Sevoflurane MAC ranged from 1.8% to 2.6% (mean ± SD, 2.2 ± 0.3%). Response entropy and state entropy were significantly higher during positive responses to tail clamping (88 ± 2 and 76 ± 2, respectively) than during negative responses to tail clamping (63 ± 3 and 52 ± 3, respectively). The difference between the 2 entropy indices did not differ between positive (11 ± 1) and negative (13 ± 1) responses to tail clamping. Response entropy and state entropy served as independent predictors of a positive response, with areas under the curve for receiver operating characteristic curves 0.810 (95% confidence interval, 0.716 to 0.903) and 0.828 (95% confidence interval, 0.741 to 0.916), respectively. Optimal cutoff points to predict a positive response were 75 for response entropy and 65 for state entropy, which corresponded to mean ± SD ORs of 25.2 ± 15.6 and 14.9 ± 7.9, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Response entropy and state entropy were good predictors of responses to tail clamping elicited during determination of sevoflurane MAC in healthy dogs.

OBJECTIVE To monitor concentrations of sulfadimidine in the paranasal sinus mucosa (PSM) of unsedated horses following IV administration of trimethoprim-sulfadimidine via in vivo microdialysis. ANIMALS 10 healthy adult horses. PROCEDURES Concentric microdialysis probes were implanted into the subepithelial layers of the frontal sinus mucosa of standing sedated horses. Four hours after implantation, trimethoprim-sulfadimidine (30 mg/kg) was administered IV every 24 hours for 2 days; dialysate and plasma samples were collected at intervals during that 48-hour period and analyzed for concentrations of sulfadimidine. The dialysate concentration and relative loss of sulfadimidine from the perfusate were used to calculate the PSM concentration. RESULTS Microdialysis probe implantation and subsequent in vivo microdialysis were successfully performed for all 10 horses. Following the first and second administration of trimethoprim-sulfadimidine, mean ± SD peak concentrations of sulfadimidine were 55.3 ± 10.3 μg/mL and 51.5 ± 8.7 μg/mL, respectively, in plasma and 9.6 ± 4.5 μg/mL and 7.0 ± 3.3 μg/mL, respectively, in the PSM. Peak sulfadimidine concentrations in the PSM were detected at 5.9 ± 2.7 hours and 5.4 ± 2.3 hours following the first and second drug administrations, respectively. For 12 hours, mean PSM sulfadimidine concentration remained greater than the minimum inhibitory concentration indicative of sulfonamide susceptibility of equine bacterial isolates (4.75 μg/mL). CONCLUSIONS AND CLINICAL RELEVANCE In vivo microdialysis for continuous monitoring of PSM sulfadimidine concentrations in unsedated horses was feasible. Intravenous administration of trimethoprim (5 mg/kg) and sulfadimidine (25 mg/kg) proved likely to be efficient for treating sinusitis caused by highly susceptible pathogens, providing that the dosing interval is 12 hours.

OBJECTIVE To investigate regional differences of relative metabolite concentrations in the brain of healthy dogs with short echo time, single voxel proton magnetic resonance spectroscopy (1H MRS) at 3.0 T. ANIMALS 10 Beagles. PROCEDURES Short echo time, single voxel 1H MRS was performed at the level of the right and left basal ganglia, right and left thalamus, right and left parietal lobes, occipital lobe, and cerebellum. Data were analyzed with an automated fitting method (linear combination model). Metabolite concentrations relative to water content were obtained, including N-acetyl aspartate, total choline, creatine, myoinositol, the sum of glutamine and glutamate (glutamine-glutamate complex), and glutathione. Metabolite ratios with creatine as the reference metabolite were calculated. Concentration differences between right and left hemispheres and sexes were evaluated with a Wilcoxon signed rank test and among various regions of the brain with an independent t test and 1-way ANOVA. RESULTS No significant differences were detected between sexes and right and left hemispheres. All metabolites, except the glutamine-glutamate complex and glutathione, had regional concentrations that differed significantly. The creatine concentration was highest in the basal ganglia and cerebellum and lowest in the parietal lobes. The N-acetyl aspartate concentration was highest in the parietal lobes and lowest in the cerebellum. Total choline concentration was highest in the basal ganglia and lowest in the occipital lobe. CONCLUSIONS AND CLINICAL RELEVANCE Metabolite concentrations differed among brain parenchymal regions in healthy dogs. This study may provide reference values for clinical and research studies involving 1H MRS performed at 3.0 T.

OBJECTIVE To develop a novel method for use of diagnostic imaging, finite element analysis (FEA), and simulated biomechanical response behavior of brain tissue in noninvasive assessment and estimation of intracranial pressure (ICP) of dogs. SAMPLE MRI data for 5 dogs. PROCEDURES MRI data for 5 dogs (1 with a geometrically normal brain that had no detectable signs of injury or disease and 4 with various degrees of geometric abnormalities) were obtained from a digital imaging archiving and communication system database. Patient-specific 3-D models composed of exact brain geometries were constructed from MRI images. Finite element analysis was used to simulate and observe patterns of nonlinear biphasic biomechanical response behavior of geometrically normal and abnormal canine brains at various levels of decreasing cerebral perfusion pressure and increasing ICP. RESULTS Changes in biomechanical response behavior were detected with FEA for decreasing cerebral perfusion pressure and increasing ICP. Abnormalities in brain geometry led to observable changes in deformation and biomechanical response behavior for increased ICP, compared with results for geometrically normal brains. CONCLUSIONS AND CLINICAL RELEVANCE In this study, patient-specific critical ICP was identified, which could be useful as a method to predict the onset of brain herniation. Results indicated that it was feasible to apply FEA to brain geometry obtained from MRI data of clinical patients and to use biomechanical response behavior resulting from increased ICP as a diagnostic and prognostic method to noninvasively assess or classify levels of brain injury in clinical veterinary settings.

OBJECTIVE To determine the effect of a commercially available multivalent killed virus vaccine on serum neutralizing (SN) and colostrum neutralizing (CN) antibodies against bovine herpesvirus (BHV) type 1 and bovine viral diarrhea virus (BVDV) types 1 and 2 in pregnant dairy cattle. ANIMALS 49 Holstein dairy cattle. PROCEDURES 25 cattle were vaccinated (IM injection) at least 60 days prior to calving (ie, at the end of the lactation period or according to the expected calving date for heifers) and again 5 weeks later. The remaining 24 cattle were not vaccinated (control group). Titers of SN antibodies were measured at the 5-week time point. Titers of SN and CN antibodies were measured at parturition. RESULTS 5 weeks after initial vaccination, titers of SN antibodies against BHV-1 and BVDV types 1 and 2 were 1:512, 1:128, and 1:2,048, respectively, in vaccinates and 1:64, 1:128, and 1:64, respectively, in unvaccinated controls. Equivalent SN antibody titers at parturition were 1:256, 1:64, and 1:512, respectively, in vaccinates and 1:128, 1:128, and 1:64, respectively, in controls. Median titers of CN antibodies against BHV-1 and BVDV types 1 and 2 were 1:1,280, 1:10,240, and 1:20,480, respectively, in vaccinates and 1:80, 1:1,280, and 1:2,560, respectively, in controls. CONCLUSIONS AND CLINICAL RELEVANCE Titers of antibodies against viral respiratory pathogens were significantly enhanced in both serum (BHV-1 and BVDV type 2) and colostrum (BHV-1 and BVDV types 1 and 2) in cattle receiving a killed virus vaccine (with no adverse reactions) before parturition. To maximize protection of bovine neonates, this method of vaccination should be considered.

OBJECTIVE To assess and compare results of anterior segment angiography of ophthalmologically normal cats following IV injection with indocyanine green and sodium fluorescein dyes. ANIMALS 10 client-owned cats. PROCEDURES Anterior segment angiography was performed in anesthetized cats following administration of 0.25% indocyanine green (1.0 mg/kg, IV) or 10% sodium fluorescein (20 mg/kg, IV) solution. All cats received both treatments. Imaging (1 eye/cat) was performed with a full-spectrum digital single-lens reflex camera equipped with an adaptor (1 image/s for 30 seconds) immediately following IV dye injection and 1, 2, 3, 4, and 5 minutes after injection. Onset and duration of arterial, capillary, and venous phases of iris vasculature were identified and compared statistically between treatments. Degree of iridal pigmentation, leakage of dye from iris vasculature, and image quality were subjectively assessed. RESULTS No differences were found in onset or duration of vascular phases between treatments. Visibility of the iris vasculature was not impaired by poor or moderate iridal pigmentation with either method. Indocyanine green provided subjectively better vascular detail and image contrast than sodium fluorescein. No vascular dye leakage was observed following indocyanine green administration. Leakage of dye from blood vessels in the stroma (in 10 cats) and presence of dye in the anterior chamber (in 5 cats) were detected after sodium fluorescein administration. CONCLUSIONS AND CLINICAL RELEVANCE Images obtained with either fluorescent dye were considered to be of diagnostic quality. Lack of leakage following indocyanine green administration suggested this treatment may have better diagnostic utility for anterior segment angiography. The photographic equipment used provided a cost-effective alternative to existing imaging systems.

OBJECTIVE To assess efficiency of gravity filtration to enhance recovery of equine bone marrow elements including stem and progenitor cells. ANIMALS 12 healthy adult horses. PROCEDURES Bone marrow aspirates were collected from the fifth sternebral body and filtered by gravitational flow to obtain bone marrow elements. Raw and harvested bone marrow and marrow effluent were evaluated for WBC and platelet counts, automated and cytomorphologic cell differential counts, mesenchymal stem cell CFUs, cell viability, and differentiation capacity. Isolated cells were analyzed for CD90 and major histocompatibility complex (MHC) class I and II antigens. RESULTS Mean cell viability of harvested bone marrow was 95.9%. Total WBCs and platelets were efficiently captured on the filter (> 95%), and mean recovery in harvested bone marrow was 30%. Cytologic cell differential counts indicated that the percentage of neutrophils was significantly less and the progenitor cell population was significantly higher and concentrated 1.56-fold in harvested bone marrow, compared with results for raw bone marrow. Flow cytometry and cell culture were used to characterize harvested bone marrow cells as positive for expression of CD90 and negative for MHCI and MHCII, which indicated stem cells with a multipotent phenotype that differentiated into chondrocytes, osteocytes, adipocytes, and tenocytes. CONCLUSIONS AND CLINICAL RELEVANCE Gravitational filtration of bone marrow efficiently yielded platelets and cells and produced a progenitor-enriched, leukocyte-reduced product, compared with raw bone marrow.

The objective of this study was to evaluate the hemodynamic effects of target-controlled infusion (TCI) of propofol alone or in combination with a constant-rate infusion (CRI) of remifentanil. Six adult dogs were given 2 treatments in a randomized crossover study with a 7-day interval between treatments. Treatment 1 was propofol (P) and treatment 2 was propofol and remifentanil (P-Rem), without any premedication. Propofol was induced using a TCI system with a predicted plasma concentration (Cp) of 6.0 μg/mL. Anesthesia was maintained within the Cp range (0.65 to 3.0 μg/mL) for 120 min and remifentanil was administered at a rate of 0.3 μg/kg body weight (BW) per minute, CRI. Cardiopulmonary variables were recorded before (baseline), during, and 120 min after drug administration. Heart rate (HR) decreased significantly in the P-Rem group (46%) compared with baseline values. In the P-Rem group, the cardiac index (CI) decreased significantly (49% to 58%) and the stroke volume (SV) decreased compared with baseline values. The systemic vascular resistance index (SVRI) increased significantly in the P-Rem group compared with baseline values. There was no difference in mean arterial pressure (MAP) between the groups. Central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) significantly increased in the P-Rem group compared with baseline values. In conclusion, the hemodynamic changes observed in this study indicate a compromise of the cardiovascular system, although the dogs in this study were healthy/euvolemic and there was no change in preload. More studies are required in order to evaluate the actual safety of the combination of propofol and remifentanil in patients with reduced cardiac reserve.

The objectives of this study were to describe demographics, basic biosecurity practices, ownership structure, and prevalence of porcine reproductive and respiratory syndrome (PRRS) in swine sites located in 3 regions in Ontario, and investigate the presence of spatial clustering and clusters of PRRS positive sites in the 3 regions. A total of 370 swine sites were enrolled in Area Regional Control and Elimination projects in Niagara, Watford, and Perth from 2010 to 2013. Demographics, biosecurity, and site ownership data were collected using a standardized questionnaire and site locations were obtained from an industry organization. Status was assigned on the basis of available diagnostic tests and/or assessment by site veterinarians. Spatial dependence was investigated using the D-function, the spatial scan statistic test and the spatial relative risk method. Results showed that the use of strict all-in all-out (AIAO) pig flow and shower before entry are uncommon biosecurity practices in swine sites, but a larger proportion of sites reported having a Danish entry. The prevalence of PRRS in the 3 regions ranged from 17% to 48% and localized high and low risk clusters were detected. Sites enrolled in the PRRS control projects were characterized by membership in multiple and overlapping ownership structures and networks, which complicates the way the results of monitoring and disease management measures are communicated to the target population.