Texture analysis of pulmonary parenchymateous changes related to pulmonary thromboembolism in dogs - a novel approach using quantitative methods.

BACKGROUND: Diagnosis of pulmonary thromboembolism (PTE) in dogs relies on computed tomography pulmonary angiography (CTPA), but detailed interpretation of CTPA images is demanding for the radiologist and only large vessels may be evaluated. New approaches for better detection of smaller thrombi include dual energy computed tomography (DECT) as well as computer assisted diagnosis (CAD) techniques. The purpose of this study was to investigate the performance of quantitative texture analysis for detecting dogs with PTE using grey-level co-occurrence matrices (GLCM) and multivariate statistical classification analyses. CT images from healthy (n = 6) and diseased (n = 29) dogs with and without PTE confirmed on CTPA were segmented so that only tissue with CT numbers between -1024 and -250 Houndsfield Units (HU) was preserved. GLCM analysis and subsequent multivariate classification analyses were performed on texture parameters extracted from these images. RESULTS: Leave-one-dog-out cross validation and receiver operator characteristic (ROC) showed that the models generated from the texture analysis were able to predict healthy dogs with optimal levels of performance. Partial Least Square Discriminant Analysis (PLS-DA) obtained a sensitivity of 94% and a specificity of 96%, while Support Vector Machines (SVM) yielded a sensitivity of 99% and a specificity of 100%. The models, however, performed worse in classifying the type of disease in the diseased dog group: In diseased dogs with PTE sensitivities were 30% (PLS-DA) and 38% (SVM), and specificities were 80% (PLS-DA) and 89% (SVM). In diseased dogs without PTE the sensitivities of the models were 59% (PLS-DA) and 79% (SVM) and specificities were 79% (PLS-DA) and 82% (SVM). CONCLUSION: The results indicate that texture analysis of CTPA images using GLCM is an effective tool for distinguishing healthy from abnormal lung. Furthermore the texture of pulmonary parenchyma in dogs with PTE is altered, when compared to the texture of pulmonary parenchyma of healthy dogs. The models' poorer performance in classifying dogs within the diseased group, may be related to the low number of dogs compared to texture variables, a lack of balanced number of dogs within each group or a real lack of difference in the texture features among the diseased dogs.

Von Willebrand factor antigen concentration in dogs with sepsis.

BACKGROUND: Von Willebrand factor (vWF) antigen concentration, a marker of endothelial activation, is increased in human patients with multiorgan failure, sepsis, or both, and is an independent predictor of survival. HYPOTHESIS/OBJECTIVES: vWF antigen concentrations are significantly higher in dogs with sepsis. ANIMALS: Fourteen dogs hospitalized with sepsis. Sepsis was defined as microbiologic or cytologic evidence of infection combined with systemic inflammatory response syndrome. Control dogs were healthy dogs, without evidence of disease. METHODS: Prospective, observational study. Dogs admitted to the intensive care unit with a diagnosis of sepsis were considered eligible for enrollment into the study. Exclusion criteria included a previous diagnosis of von Willebrand disease or a recent history of a plasma transfusion. Citrated plasma samples were collected for analysis of vWF antigen by ELISA. All samples were drawn from dogs during hospitalization. Data between populations were analyzed using nonparametric statistical analysis with a P value < .05 considered significant. RESULTS: Twenty-five dogs were enrolled; 14 dogs with sepsis and 11 control dogs. The median vWF antigen concentration in dogs with sepsis was 156% (range, 117-200%), which was significantly higher than healthy dogs (105%; range, 44-155%, P < .005). There was no difference between survivors and nonsurvivors with a median vWF antigen concentration of 144% (range, 136-201%) in survivors (n = 7) and 159% (range, 122-174%) in nonsurvivors (n = 7) (P = .5). CONCLUSIONS AND CLINICAL IMPORTANCE: vWF is increased in dogs with sepsis, possibly reflecting endothelial activation. Further exploration of endothelial function is warranted in critically ill dogs.

Perceptions of quality of life and priorities of owners of cats with heart disease.

BACKGROUND: Owners' perceptions and priorities regarding quality of life (QoL) are important considerations given the unknown efficacy of many commonly administered medications, stress of hospital visits, difficulties providing home care, and personal choices including euthanasia. OBJECTIVE: To describe the relative importance of quality versus quantity of life to owners of cats with heart disease. ANIMALS: Two hundred and thirty-nine cats with heart disease. METHODS: Prospective questionnaire-based clinical study. Cat owners completed a questionnaire to identify important parameters when assessing their cat's QoL, the relative importance of quality versus quantity of life, and willingness to trade survival time for QoL. Variables associated with these parameters were evaluated with multivariate analyses. RESULTS: Appetite, owner interaction, sleep patterns, and litterbox habits were deemed important to QoL. Concern over pet suffering was significantly greater than concern over life expectancy. Ninety-three percent of owners were willing to trade survival time for good QoL; 57% of these were willing to trade up to 6 months. On multivariate analysis, the only factor significantly (P=.002) associated with willingness to trade 6 months was study site. Owner concern regarding stress of administering medications at home increased with number and frequency of medications. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicated that QoL is more important to owners of cats with heart disease than longevity. The various priorities and concerns of cat owners should be taken into account in order to provide optimal care.

Relationship among plasma amino acids, C-reactive protein, illness severity, and outcome in critically ill dogs.

BACKGROUND: Alterations in circulating amino acids have been documented in animal models and in critically ill people but have not been evaluated in dogs with spontaneously occurring disease. HYPOTHESIS/OBJECTIVES: To compare amino acid concentrations in critically ill dogs and healthy controls and to investigate potential relationships among amino acids, markers of inflammation, illness severity, and clinical outcome. ANIMALS: Forty-eight critically ill dogs and 24 healthy control dogs. METHODS: Plasma was analyzed for amino acids and C-reactive protein (CRP) was measured in serum. The Fischer ratio (the molar ratio of branched chain amino acids [BCAA] to aromatic amino acids [AAA]) and survival prediction index (SPI2) were calculated. RESULTS: Median CRP concentrations were significantly higher in the critically ill dogs compared with controls (P < .001). Critically ill dogs had significantly lower concentrations of alanine (P= .001), arginine (P < .001), citrulline (P < .001), glycine (P < .001), methionine (P < .001), proline (P < .001), and serine (P= .001) but significantly higher concentrations of lysine (P= .02) and phenylalanine (P < .001; Table 1). This pattern resulted in a significantly lower Fischer ratio (P= .001) in the critically ill group. Median SPI2 score was significantly higher in dogs that survived (P= .03). Concentrations of arginine (P= .02), isoleucine (P= .01), leucine (P= .04), serine (P= .04), valine (P= .04), total BCAA (P= .03), and the Fischer ratio (P= .03) were significantly higher in survivors compared with nonsurvivors. CONCLUSIONS AND CLINICAL IMPORTANCE: Critically ill dogs have altered amino acid profiles and additional research to investigate potential benefits of amino acid supplementation is warranted.

Lack of evidence of pregnancy-induced alloantibodies in dogs.

BACKGROUND: It is controversial whether or not pregnant bitches become sensitized to red blood cell (RBC) antigens. HYPOTHESIS: Bitches do not develop alloantibodies to RBC antigens during gestation and can be used safely as blood donors. ANIMALS: The study group included 35 healthy female dogs with a prior history of 1 (n = 12), 2 (n = 14), or >or= 3 (n = 9) pregnancies. The control group consisted of 15 healthy female dogs without any history of pregnancy. METHODS: All dogs were blood typed for dog erythrocyte antigens (DEA) 1.1, 1.2, 3, 4, 5, and 7 using ethylenediaminetetraacetic acid blood samples and polyclonal antisera. Antibody screening was performed with serum and canine RBC panels of known blood type. An autocontrol and direct antiglobulin test were performed to rule out the presence of autoantibodies. RESULTS: The only alloantibodies identified were those against DEA 7 and the prevalence of anti-DEA 7 alloantibodies was similar in dogs with known history of pregnancy (11.4%) and in the control group (13.3%). CONCLUSIONS AND CLINICAL IMPORTANCE: These results confirm previous studies and clinical transfusion medicine experience. Naturally occurring anti-DEA 7 alloantibodies have been reported but their clinical relevance has not been shown. Pregnancy does not appear to sensitize dogs to RBC antigens. Consequently, dogs with prior history of pregnancy can be used safely as blood donors. Conversely, no additional pretransfusion compatibility studies would be required should these dogs themselves need to be transfused.

Serial evaluation of protein C and antithrombin in dogs with sepsis.

BACKGROUND: Protein C (PC) and antithrombin (AT) activities are decreased in humans with severe sepsis, and persistent changes are associated with decreased survival. In dogs with sepsis, PC and AT have been shown to be decreased at the time of diagnosis. HYPOTHESIS: PC and AT activities change significantly over time in dogs with sepsis and may be related to outcome. ANIMALS: Twelve dogs with naturally occurring sepsis. METHODS: Blood was collected from 12 dogs with sepsis, defined as histopathologic or microbiologic confirmation of infection and two of the following: hypo- or hyperthermia, tachycardia, tachypnea, leukopenia, leukocytosis, or >3% bands. The time of 1st sampling was considered day 1 and sampling was repeated every 24 hours for 5 days or until discharge or death. Changes over time were analyzed by ANOVA with repeated measures, and the association between PC and AT and outcome was determined by a 2-equation treatment effects model. RESULTS: Nine dogs and 11 dogs had decreased PC and AT activity on day 1, respectively (mean PC, 66.0 +/- 25.8%; mean AT, 48.1 +/- 16.5%). PC activity significantly decreased from day 1 to day 2 (P= .001), then increased over time. Changes in PC (P < .001) and AT (P < .001) over time were likely associated with outcome with nonsurvivors having lower PC and AT activities than survivors. CONCLUSION: Results of this preliminary study show that PC and AT activities change significantly over time in dogs with sepsis and both are likely related to survival.

Thromboelastographic evaluation of hemostatic function in dogs with disseminated intravascular coagulation.

BACKGROUND: There is considerable variation in the coagulation profile of dogs with disseminated intravascular coagulation (DIC), making it difficult to assess overall hemostatic function. OBJECTIVES: To characterize the overall hemostatic state in dogs with DIC, by use of tissue factor-activated thromboelastography (TF-TEG), and to determine whether there is an association between hemostasis and outcome. ANIMALS: 50 dogs with DIC. METHODS: Dogs admitted to the intensive care units, with an underlying disease known to predispose to DIC, were prospectively assessed with TF-TEG. Citrated blood samples were collected daily during hospitalization and an extended coagulation panel and TF-TEG were performed. Diagnosis of DIC was based on expert opinion. RESULTS: Hemostatic dysfunction was observed on the TF-TEG profile in 33/50 of the dogs, of which 22/50 were hypercoagulable and 11/50 were hypocoagulable based on the TF-TEG G value alone. There were significant differences in k, alpha, and MA values (P < .0001) among hypo-, normo-, and hypercoagulable dogs. There was a significant difference in case fatality rate between hypo- (64%) and hypercoagulable (32%) dogs (relative risk = 2.38; P= .04). Dogs that died had significantly lower antithrombin activity (P= .03) and higher d-dimer concentration (P= .03) than survivors. CONCLUSIONS: The most common overall hemostatic abnormality in dogs diagnosed with DIC was hypercoagulability, and there was significant difference in survival between hyper- and hypocoagulable dogs. The results suggest TF-TEG is valuable in the assessment of hemostatic function in dogs diagnosed with DIC.

Hypercoagulability in cats with cardiomyopathy.

BACKGROUND: Arterial thromboembolism (ATE) is a common complication of feline cardiomyopathy; however, the pathogenesis of ATE is unknown. HYPOTHESIS: Systemic activation of the coagulation cascade (hypercoagulability) and endothelial injury promote ATE in cardiomyopathic cats. ANIMALS: Healthy cats (n = 30) and 3 groups of cardiomyopathic cats: Group (1) left atrial enlargement only (LAE [n = 11]), ie, left atrial to aortic ratio >1.4; Group (2) LAE with spontaneous echocardiographic contrast, atrial thrombi or both (SEC-T [n = 16]); and Group (3) acute ATE with LAE (n = 16). METHODS: Hypercoagulability was defined by 2 or more laboratory abnormalities reflecting coagulation factor excess (high fibrinogen concentration or Factor VIII coagulant activity), inhibitor deficiency (low antithrombin activity), or thrombin generation (high thrombin-antithrombin complex [TAT] and d-dimer concentrations). High von Willebrand factor antigen concentration (vWF : Ag) was considered a marker of endothelial injury. Data were analyzed using nonparametric statistics. RESULTS: The 3 groups of cats with cardiac disease had higher median fibrinogen concentrations than did the healthy cats. Criteria of hypercoagulability were found exclusively in cats with SEC-T (50%) and ATE (56%). Hypercoagulability was not associated with left atrial size or congestive heart failure (CHF). ATE cats had significantly higher median vWF : Ag concentration than did the other groups. CONCLUSION AND CLINICAL IMPORTANCE: Systemic hypercoagulability is evident in many cardiomyopathic cats, often without concurrent CHF or overt ATE. Hypercoagulabilty may represent a risk factor for ATE. High vWF : Ag in ATE cats was attributed to downstream endothelial injury from the occlusive thrombus.

Diagnosis of canine pulmonary thromboembolism by computed tomography and mathematical modelling using haemostatic and inflammatory variables.

There is no evidence-based diagnostic approach for diagnosis of pulmonary thromboembolism (PTE) in dogs. Many dogs with diseases that predispose to thrombosis are hypercoagulable when assessed with thromboelastography (TEG), but no direct link has been established. The aims of this study were: (1) to investigate if diseased dogs with PTE, diagnosed by computed tomography pulmonary angiography (CTPA), had evidence of hypercoagulability by TEG; (2) to characterise haemostatic and inflammatory changes in dogs with PTE; (3) to construct models for prediction of PTE based on combinations of haemostatic and inflammatory variables; and (4) to evaluate the performance of D-dimer measurement for prediction of PTE. Twenty-five dogs were included in this prospective observational study (PTE: n=6; non-PTE: n=19). Clot strength G values did not differ between the PTE and non-PTE groups in tissue factor (TF) or kaolin-activated TEG analyses. Haemostatic and inflammatory variables did not differ between the two groups. Linear discriminant analysis generated a model for prediction of PTE with a sensitivity and specificity of 100% when TF results were used as TEG data, and a model with sensitivity of 83% and specificity of 100% when kaolin results were used as TEG data. Receiver operating characteristic analysis of D-dimer levels showed that a value of >0.3mg/L yielded a sensitivity of 100% and a specificity of 71.4%. In conclusion, the study supports CTPA as method for diagnosing canine PTE, but shows that TEG alone cannot identify dogs with PTE. Models for prediction of PTE were generated, but require further validation.

Canine awake head-out plethysmography (HOP): characterization of external resistive loading and spontaneous laryngeal paralysis.

We applied a novel head-out plethysmographic (HOP) method to study awake canine responses to external resistive loading and natural laryngeal paralysis. Measurements of inspiratory and expiratory specific airway resistance (sRaw(insp), sRaw(exp)) were obtained before and after uni- and bidirectional loading (R(add) = 5 cmH(2)O/L/s) in large-breed dogs (n = 9). Mean sRaw(insp) after inspiratory, and sRaw(exp) after expiratory loading were 31.4 and 33.3 cmH(2)Os, respectively. Bidirectional loads induced a significantly greater rise in both sRaw(insp) and sRaw(exp) (55.1 and 61.3 cmH(2)Os) compared to unidirectional loading (P < 0.001). Yet, type of loading did not affect flow-volume indices. The mean R(aw) of dogs was 4.81 cmH(2)O/L/s. Expiratory loading resulted in a significant 8.8% increase in functional-residual-capacity (FRC), compared to FRC(baseline) (76.7 ml/kg). Dogs (n = 5) with laryngeal paralysis demonstrated a significant increase in sR(aw) and R(aw) compared to controls without changes in FRC. In conclusion, HOP precisely characterized sR(aw) in response to external resistive loading. Hence, we could accurately quantify airway obstruction in awake dogs with laryngeal paralysis.

Hospital-acquired Anemia in Critically Ill Dogs and Cats: A Multi-Institutional Study.

BACKGROUND: Hospital-acquired anemia is commonly described in people but limited information currently is available regarding its prevalence in animals. HYPOTHESIS/OBJECTIVES: Assess the prevalence of hospital-acquired anemia in hospitalized critically ill dogs and cats, and examine its relationship with phlebotomy practices, transfusion administration, and survival to discharge. ANIMALS: Eight hundred and fifty-one client-owned animals (688 dogs and 163 cats). METHODS: A multicenter, observational study was conducted in which packed cell volume (PCV) was recorded at the time of admission and on subsequent hospitalization days. Signalment, number of blood samples obtained, underlying disease, whether or not blood products were administered, duration of hospitalization, and survival to discharge were recorded. RESULTS: Admission anemia prevalence was 32%, with overall prevalence during the hospitalization period of 56%. The last recorded PCV was significantly lower than the admission PCV for both dogs (admission PCV, 42% [range, 6-67%]; last recorded PCV, 34% [range, 4-64%], P < .0001) and cats (admission PCV, 31% [range, 6-55%]; last recorded PCV, 26% [range, 10-46%], P < .0001). Patients that developed anemia had significantly more blood samples obtained (nonanemic, 5 blood samples [range, 2-54]; anemic, 7 blood samples [range, 2-49], P < .0001). Hospitalized cats were significantly more likely to develop anemia compared to dogs (P < .0001), but anemic dogs were significantly less likely to survive to discharge (P = .0001). Surgical patients were at higher risk of developing hospital-acquired anemia compared to medical patients (OR, 0.63; 95% CI, 0.4-0.9; P = .01). CONCLUSIONS AND CLINICAL RELEVANCE: Hospital-acquired anemia occurred frequently, especially in surgical patients. Additional studies focused on the direct effect of phlebotomy practices on the likelihood of anemia development in hospitalized animals are warranted.

Differentiation of Cardiac from Noncardiac Pleural Effusions in Cats using Second-Generation Quantitative and Point-of-Care NT-proBNP Measurements.

BACKGROUND: Pleural effusion is a common cause of dyspnea in cats. N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurement, using a first-generation quantitative ELISA, in plasma and pleural fluid differentiates cardiac from noncardiac causes of pleural effusion. HYPOTHESIS/OBJECTIVES: To determine whether NT-proBNP measurements using second-generation quantitative ELISA and point-of-care (POC) tests in plasma and pleural fluid distinguish cardiac from noncardiac pleural effusions and how results compare to the first-generation ELISA. ANIMALS: Thirty-eight cats (US cohort) and 40 cats (UK cohort) presenting with cardiogenic or noncardiogenic pleural effusion. METHODS: Prospective cohort study. Twenty-one and 17 cats in the US cohort, and 22 and 18 cats in the UK cohort were classified as having cardiac or noncardiac pleural effusion, respectively. NT-proBNP concentrations in paired plasma and pleural fluid samples were measured using second-generation ELISA and POC assays. RESULTS: The second-generation ELISA differentiated cardiac from noncardiac pleural effusion with good diagnostic accuracy (plasma: sensitivity, 95.2%, specificity, 82.4%; pleural fluid: sensitivity, 100%, specificity, 76.5%). NT-proBNP concentrations were greater in pleural fluid (719 pmol/L (134-1500)) than plasma (678 pmol/L (61-1500), P = 0.003), resulting in different cut-off values depending on the sample type. The POC test had good sensitivity (95.2%) and specificity (87.5%) when using plasma samples. In pleural fluid samples, the POC test had good sensitivity (100%) but low specificity (64.7%). Diagnostic accuracy was similar between first- and second-generation ELISA assays. CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of NT-proBNP using a quantitative ELISA in plasma and pleural fluid or POC test in plasma, but not pleural fluid, distinguishes cardiac from noncardiac causes of pleural effusion in cats.

Massive haemorrhage associated with inadvertent incision of a suspected carotid artery pseudoaneurysm in a cat.

A 12-year-old, castrated male, domestic long-haired cat experienced massive haemorrhage associated with an incision of a swelling on the neck 2 weeks after right-sided ventral bulla osteotomy. Emergent control of haemorrhage was gained through unilateral carotid artery ligation. Cardiopulmonary resuscitation was provided in conjunction with massive blood transfusion. The cat made an unremarkable recovery. Carotid artery pseudoaneurysm due to surgical disruption of the carotid artery during ventral bulla osteotomy, specifically through the use of self-retaining retractors, was suspected. This case highlights the development of pseudoaneurysm as a potential complication of head and neck surgery, and additionally describes a case of massive transfusion in a cat.

Cholinergic reactivity of tracheal smooth muscle after infection with feline herpesvirus I.

Airway responsiveness was studied in cats 3 or 6 days after exposure to feline herpesvirus I. Control cats were sham inoculated with tissue culture media. Intrathoracic airway caliber was evaluated by pulmonary resistance (RL) and dynamic compliance (Cdyn). Trachealis shortening was quantitated with microfoil strain gauges, which measured the external diameter of tracheal ring 4. Airway smooth muscle contraction was produced using vagal stimulation and local infusion of acetylcholine. The diameter of tracheal ring 4 decreased with increasing frequency of vagal stimulation, and there was more constriction at 3 (PID3) than at 6 days postinfection (PID6) or in control cats. RL increased and Cdyn tended to decrease with increasing frequency of stimulation, but there was no difference between control and infected cats. Infected and control cats did not differ in their response to locally infused acetylcholine. Virus was consistently cultured from conjunctival, nasal, and oral mucous membranes, trachea, and main stem bronchi at PID3 but not from the trachea and main stem bronchi at PID6. Virus was never isolated distal to the main stem bronchi. Tracheal hyperresponsiveness to vagal stimulation correlates with the presence of virus at PID3 and is apparently presynaptic in origin.

Tidal breathing flow-volume loops in healthy and bronchitic cats.

Tidal breathing flow-volume loops (TBFVL) were obtained from 19 healthy cats and 7 cats with chronic bronchial disease. Peak inspiratory flow (PIF) occurred late in the inspiratory cycle and was preceded by a gradual but more linear increase in the flow rate. Peak expiratory flow (PEF) occurred early during expiration and was followed by a curvilinear decrease in flow to a point near the end of expiration where flow ceased. The loops obtained were generally reproducible. The mean coefficient of variation (CV) for TBFVL indices of healthy cats ranged from 5.6% to 21.9%. Loop indices from cats with chronic bronchial disease had a mean CV between 6.6% and 28.4%. Significant differences were noted in the bronchitic cats' TBFVLs, including an increased ratio of expiratory time to inspiratory time, lower expiratory flow rates, decreased area under total and peak expiratory flow curves, and decreased tidal breathing expiratory volumes (TBEV) at 0.1 and 0.5 seconds. Selected TBFVL indices were also significantly reduced. TBFVL evaluation in the cat is easy to perform, is reproducible, and has allowed for the detection of changes during tidal breathing in cats with histories and physical findings of chronic lower airway disease.

Bronchopulmonary disease in the cat: historical, physical, radiographic, clinicopathologic, and pulmonary functional evaluation of 24 affected and 15 healthy cats.

The results of clinical and pulmonary functional evaluation of 24 cats with bronchopulmonary disease and 15 healthy cats are presented. Affected cats had historical evidence of excessive reflexes (coughing, sneezing); physical evidence of airway secretions (crackles), obstruction (wheezing), and increased tracheal sensitivity; radiographic evidence of bronchial and interstitial lung disease; and cytological evidence of airway inflammation or mucous secretions. Bacterial isolates from healthy and affected cats were predominantly Gram-negative rods, indicating that bronchi of cats are not always sterile and that normal flora should be considered in interpreting cultures from cats with suspected bronchopulmonary disease. Cats were grouped according to relative disease severity based on scored historical, physical, and radiographic abnormalities. The mean (+/- standard deviation) baseline lung resistance measurement in healthy cats was 28.9 cm H2O/L/s (+/- 6.2 cm H2O/L/s), whereas in mildly, moderately, and severely affected cats it was 38.3 cm H2O/L/s (+/- 21.5 cm H2O/L/s), 44.8 cmH2O/L/s (+/- 7.7 cm H2O/L/s), and 105.2 cm H2O/L/s (+/- 66.9 cm H2O/L/s), respectively. In healthy cats, dynamic lung compliance was 19.8 (+/- 7.4), whereas in mildly, moderately, and severely affected cats it was 14.7 mL/cm H2O (+/- 3.8 mL/cm H2O), 17.7 mL/cm H2O (+/- 6.9 mL/cm H2O), and 13.0 mL/cm H2O (+/- 7.9 mL/cm H2O), respectively. Thus, airway obstruction was present in many of the affected cats. Based on acute response to the bronchodilator, terbutaline, airway obstruction was partially reversible in many affected cats, although the degree of reversibility varied. Furthermore, based on bronchoprovocation testing, 6 (of 7) affected cats evaluated also had increased airway responsiveness to aerosolized methacholine.

Plasma homocysteine, B vitamins, and amino acid concentrations in cats with cardiomyopathy and arterial thromboembolism.

Arterial thromboembolism (ATE) is a common complication of cats with cardiomyopathy (CM), but little is known about the pathophysiology of ATE. In people, high plasma concentrations of homocysteine and low B vitamin concentrations are risk factors for peripheral vascular disease. In addition, low plasma arginine concentrations have been linked to endothelial dysfunction. The purpose of this study was to compare concentrations of homocysteine, B vitamins, and amino acids in plasma of normal cats to those of cats with CM and ATE. Plasma concentrations of homocysteine, vitamin B6, vitamin B12, folate, and amino acids were measured in 29 healthy cats, 27 cats with CM alone, and 28 cats with both CM and ATE. No differences were found between groups in homocysteine or folate. Mean vitamin B12 concentration (mean +/- standard deviation) was lower in cats with ATE (866 +/- 367 pg/mL) and cats with CM (939 +/- 389 pg/mL) compared with healthy controls (1,650 +/- 700 pg/mL; P < .001). Mean vitamin B6 concentration was lower in cats with ATE (3,247 +/- 1.215 pmol/mL) and cats with CM (3,200 +/- 906 pmol/mL) compared with healthy control animals (4,380 +/- 1,302 pmol/mL; P = .005). Plasma arginine concentrations were lower in cats with ATE (75 +/- 33 nmol/mL) compared with cats with CM (106 +/- 25 nmol/mL) and healthy control animals (96 +/- 25 nmol/ mL; P < .001). Vitamin B12 concentration was significantly correlated with left atrial size. We interpret the results of this study to suggest that vitamin B12 and arginine may play a role in CM and ATE of cats.

Measurement of upper airway resistance in awake untrained dolichocephalic and mesaticephalic dogs.

A technique for measuring upper airway resistance was developed in awake untrained dolichocephalic and mesaticephalic dogs. Twenty healthy dogs, 10 Collies (group A--dolichocephalic) and 10 mixed-breed dogs (group B--mesaticephalic), were studied. All dogs tolerated the procedure well, and adverse effects were not observed. Mean (+/- SEM) value for upper airway resistance was 7.1 +/- 0.50 cm of H2O/L/L/s. There was a trend toward lower upper airway resistance (R(uaw)) values in group-A dogs, compared with those in group-B dogs. Values of R(uaw) were reproducible for an individual dog. The mean individual dog coefficient of variation for R(uaw) was 7.5%. The overall R(uaw) coefficient of variation for all 20 dogs was 31.4%. This technique for measuring upper airway resistance in dogs is clinically applicable for objectively assessing response to treatment of obstructive upper airway disorders.

Effect of sampling site, repeated sampling, pH, and PCO2 on plasma lactate concentration in healthy dogs.

OBJECTIVE: To characterize the variation in plasma lactate concentration among samples from commonly used blood sampling sites in conscious, healthy dogs. ANIMALS: 60 healthy dogs. PROCEDURE: Cross-sectional study using a replicated Latin square design. Each dog was assigned to 1 of 6 groups (n = 10) representing all possible orders for 3 sites (cephalic vein, jugular vein, and femoral artery) used to obtain blood. Samples were analyzed immediately, by use of direct amperometry for pH, PO2, Pco2, glucose, and lactate concentration. RESULTS: Significant differences in plasma lactate concentrations were detected among blood samples from the cephalic vein (highest), femoral artery, and jugular vein (lowest). Mean plasma lactate concentration in the first sample obtained, irrespective of sampling site, was lower than in subsequent samples. Covariation was identified among plasma lactate concentration, pH, and PCO2, but correlation coefficients were low. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma lactate concentrations differed among blood samples from various sites. A reference range for plasma lactate concentration was 0.3 to 2.5 mmol/L. Differences in plasma lactate concentrations among samples from various sites and with repeated sampling, in healthy dogs, are small. Use of the reference range may facilitate the clinical use of plasma lactate concentration in dogs.