Association of hyponatremia and hyperglycemia with outcome in dogs with congestive heart failure

Objective: To evaluate plasma sodium and glucose concentrations in dogs with congestive heart failure (CHF) prior to treatment and evaluate the differences between survivors and non‐survivors. Design: Retrospective study. Animals: Fifty‐nine dogs with CHF prior to receiving cardiac medication. Interventions: None. Measurements and main results: The mean plasma sodium concentration in dogs with CHF was below the reference range (144–156 mmol/L) and significantly lower (P=0.009) in non‐survivors (141±6 mmol/L) compared with survivors (147±4 mmol/L). The mean plasma glucose concentration was above the reference range (76–117 mg/dL) and significantly higher (P=0.004) in non‐survivors (128±52 mg/dL) compared with survivors (100±13 mg/dL). Forty‐four percent of non‐survivors had concurrent low plasma sodium and high plasma glucose concentrations, whereas no survivors had both abnormalities (P<0.0001). Conclusions: Lower plasma sodium and higher plasma glucose are associated with a worse outcome in dogs with CHF.     

Cardiovascular function,pulmonary gas exchange and tissue oxygenation in isoflurane-anesthetized,mechanically ventilated Beagle dogs with four levels of positive end-expiratory pressure

ObjectivesTo compare pulmonary gas exchange, tissue oxygenation and cardiovascular effects of four levels of end-expiratory pressure: no positive end-expiratory pressure (ZEEP), positive end-expiratory pressure (PEEP) of maximal respiratory system compliance (PEEPmaxC_rs), PEEPmaxC_rs + 2 cmH₂O (PEEPmaxC_rs+2), PEEPmaxC_rs + 4 cmH₂O (PEEPmaxC_rs+4), in isoflurane-anesthetized dogs.Study designProspective randomized crossover study.AnimalsA total of seven healthy male Beagle dogs, aged 1 year and weighing 10.2 ± 0.7 kg (mean ± standard deviation).MethodsThe dogs were administered acepromazine and anesthesia was induced with propofol and maintained with isoflurane. Ventilation was controlled for 4 hours with ZEEP, PEEPmaxC_rs, PEEPmaxC_rs+2 or PEEPmaxC_rs+4. Cardiovascular, pulmonary gas exchange and tissue oxygenation data were evaluated at 5, 60, 120, 180 and 240 minutes of ventilation and compared using a mixed-model anova followed by Bonferroni test. p < 0.05 was considered significant.ResultsCardiac index (CI) and mean arterial pressure (MAP) were lower in all PEEP treatments at 5 minutes when compared with ZEEP. CI persisted lower throughout the 4 hours only in PEEPmaxC_rs+4 with the lowest CI at 5 minutes (2.15 ± 0.70 versus 3.45 ± 0.94 L minute^–1 m^–2). At 180 and 240 minutes, MAP was lower in PEEPmaxC_rs+4 than in PEEPmaxC_rs, with the lowest value at 180 minutes (58 ± 7 versus 67 ± 7 mmHg). Oxygen delivery index (DO₂I) was lower in PEEPmaxC_rs+4 than in ZEEP at 5, 60, 120 and 180 minutes. Venous admixture was not different among treatments.Conclusion and clinical relevanceThe use of PEEP caused a transient decrease in MAP and CI in lung-healthy dogs anesthetized with isoflurane, which improved after 60 minutes of ventilation in all levels of PEEP except PEEPmaxC_rs+4. A clinically significant improvement in arterial oxygenation and DO₂I was not observed with PEEPmaxC_rs and PEEPmaxC_rs+2 in comparison with ZEEP, whereas PEEPmaxC_rs+4 decreased DO₂I.     

Pulmonary blood volume in mitral regurgitation in Cavalier King Charles spaniels

Background: Pulmonary edema and venous congestion are well‐recognized signs of congestive heart failure (CHF) in advanced canine chronic mitral regurgitation (MR). However, little is known about pulmonary blood volume (PBV), blood pulmonary transit time (PTT), and the regulation of these. Objectives: To measure and evaluate the relationships of PBV, forward stroke volume (FSV), and heart rate normalized blood pulmonary transit time (nPTT) in healthy dogs and dogs with MR. Animals: Thirty‐three Cavalier King Charles Spaniels; 11 healthy, 4 in modified New York Heart Association (NYHA) class I, 11 in class II, and 7 in CHF. Methods: Heart rate normalized PTTs were measured by radionuclide angiocardiography. Left ventricular end diastolic and systolic diameter, left atrial/aortic root ratio, and FSV were measured by echocardiography. PBV and pulmonary blood volume index (PBVI) were calculated by established formulas. Results: PBVI was 308 ± 56 (mean ± SD) mL/m² for healthy dogs, 287 ± 51 mL/m² in NYHA class I, 360 ± 66 mL/m² in Class II, and 623 ± 232 mL/m² in CHF (P= .0008). Heart rate normalized PTT, not FSV, was a predictor of PBV (r= 0.92 and 0.02, respectively). Conclusions and Clinical Importance: Increased PBV, not decreased FSV, is the main cause of increased nPTT in MR. Increased nPTT can be used as an indicator of abnormal cardiopulmonary function in dogs with MR.     

Cardiovascular and respiratory effects of two doses of fentanyl in the presence or absence of bradycardia in isoflurane-anesthetized dogs

Objective

To compare the cardiopulmonary effects of low and high doses of fentanyl before and after the correction of bradycardia in isoflurane-anesthetized dogs.

A comparison in dogs of medetomidine,with or without MK‐467, and the combination acepromazine‐butorphanol as premedication prior to anaesthesia induced by propofol and maintained with isoflurane

ObjectiveTo compare the haemodynamic effects of three premedicant regimens during propofol-induced isoflurane anaesthesia.Study designProspective, randomized cross-over study.AnimalsEight healthy purpose-bred beagles aged 4 years and weighing mean 13.6 ± SD 1.9 kg.MethodsThe dogs were instrumented whilst under isoflurane anaesthesia prior to each experiment, then allowed to recover for 60 minutes. Each dog was treated with three different premedications given intravenously (IV): medetomidine 10 μg kg^?1 (MED), medetomidine 10 μg kg^?1 with MK-467 250 μg kg^?1 (MMK), or acepromazine 0.01 mg kg^?1 with butorphanol 0.3 mg kg^?1 (AB). Anaesthesia was induced 20 minutes later with propofol and maintained with isoflurane in oxygen for 60 minutes. Heart rate (HR), cardiac output, arterial blood pressures (ABP), central venous pressure (CVP), respiratory rate, inspired oxygen fraction, rectal temperature (RT) and bispectral index (BIS) were measured and arterial and venous blood gases analyzed. Cardiac index (CI), systemic vascular resistance index (SVRI), oxygen delivery index (DO₂I), systemic oxygen consumption index (VO₂I) and oxygen extraction (EO₂) were calculated. Times to extubation, righting, sternal recumbency and walking were recorded. The differences between treatment groups were evaluated with repeated measures analysis of covariance.ResultsHR, CI, DO₂I and BIS were significantly lower with MED than with MMK. ABP, CVP, SVRI, EO₂, RT and arterial lactate were significantly higher with MED than with MMK and AB. HR and ABP were significantly higher with MMK than with AB. However, CVP, CI, SVRI, DO₂I, VO₂I, EO₂, T, BIS and blood lactate did not differ significantly between MMK and AB. The times to extubation, righting, sternal recumbency and walking were significantly shorter with MMK than with MED and AB.Conclusions and clinical relevanceMK-467 attenuates certain cardiovascular effects of medetomidine in dogs anaesthetized with isoflurane. The cardiovascular effects of MMK are very similar to those of AB.     

Thrombelastography in horses with acute gastrointestinal disease

Background: Coagulopathies in horses with gastrointestinal disease are frequently identified and associated with morbidity and fatality. Objective: Determine if thrombelastography (TEG) identifies abnormalities associated with lesion type, presence of systemic inflammatory response syndrome (SIRS), morbidity, and fatality more consistently than traditional coagulation testing. Animals: One‐hundred and one horses examined for gastrointestinal disease and 20 healthy horses. Methods: TEG, tissue factor (TF)‐TEG, and traditional coagulation panels parameters and percentages of horses with coagulopathies were compared for lesion type, presence of SIRS, complications, and survival. Results: Changes in individual parameters and increased incidence of coagulopathies were associated with fatality (R, P= .007; k‐value [K], P= .004; clot lysis [CL]30, P= .037; CL60, P= .050; angle [Ang], P= .0003; maximum amplitude [MA], P= .006; lysis [Ly]30, P= .042; Ly60, P= .027; CI, P= .0004; ≥ 2 TEG coagulopathies, P= .013; ≥ 3 TEG coagulopathies, P= .038; TF‐R, P= .037; TF‐K, P= .004; TF‐CL30, P < .0001; TF‐CL60, P < .0001; TF‐Ang, P= .005; TF‐Ly30, P= .0002; TF‐Ly60, P < .0001; TF‐CI, P= .043; ≥ 1 TF‐TEG coagulopathies, P= .003; ≥ 2 TF‐TEG coagulopathies, P= .0004; prothrombin tme [PT], P < .0001; activated partial throboplastin time [aPTT], P= .021), inflammatory lesions (MA, P= .013; TF‐CL30, P= .033; TF‐CL60, P= .010; TF‐Ly60, P= .011; ≥ 1 TF‐TEG coagulopathy, P= .036; ≥ 2 TF‐TEG coagulopathy, P= .0007; PT, P= .0005; fibrinogen, P= .019), SIRS (MA, P= .004; TF‐CL30, P= .019; TF‐CL60, P= .013; TF‐Ly30, P= .020; TF‐Ly60, P= .010; PT, P < .0001; aPTT, P= .032; disseminated intravascular coagulation, P= .005), and complications (ileus: aPTT, P= .020; diarrhea: TF‐CL30, P= .040; TF‐Ly30, P= .041; thrombophlebitis: ≥ 1 TF‐TEG coagulopathy, P= .018; laminitis: MA, P= .004; CL60, P= .045; CI, P= .036; TF‐MA, P= .019; TF‐TEG CI, P= .019). Abnormalities in TEG and TF‐TEG parameters were indicative of hypocoagulation and hypofibrinolysis. Conclusions and Clinical Importance: TEG identifies changes in coagulation and fibrinolysis associated with lesion type, SIRS, morbidity, and fatality in horses with gastrointestinal disease.     

Hematology and Serum Biochemistry of Feline Immunodeficiency Virus-Infected and Feline Leukemia Virus-Infected Cats

Background: Hematological and biochemical values in cats naturally infected by feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV) are not completely documented. Objective: Report differences in laboratory values between FIV‐ or FeLV‐infected and noninfected and between FIV‐ and FeLV‐infected cats. Animals: Three thousand seven hundred and eighty client‐owned cats tested for FIV and FeLV. Methods: Retrospective study. Evaluation of clinicopathologic changes in cats with defined FIV and FeLV status and for which laboratory data were available. Results: FIV‐infected cats were more likely to be neutropenic (odds ratio [OR]=3.6, 95% confidence interval [95% CI] 2.1–6.2, P < .0001) and had lower serum activities of aspartate aminotransferase and glutamate dehydrogenase than control cats; serum total protein (8.1 ± 1.1 versus 7.6 ± 1.3 g/dL, P < .001) and γ‐globulin concentrations (2.2 ± 1.1 versus 1.7 ± 1.3 g/dL, P < .001) were higher than in uninfected cats. Compared with controls, FeLV‐infected cats had a higher risk of anemia (OR = 3.8, 95% CI 2.4–6.0, P < .0001), thrombocytopenia (OR = 5.0, 95% CI 3.0–8.4, P < .0001), neutropenia (OR = 3.6, 95% CI 2.1–6.1, P < .0001), lymphocytosis (OR = 2.8, 95% CI 1.6–4.8, P= .0002), and lower erythrocyte counts (6.13 ± 2.95 × 10³ versus 8.72 ± 2.18 × 10³/μL, P < .001), thrombocyte counts (253.591 ± 171.841 × 10³ versus 333.506 ± 156.033 × 10³/μL, P < .001), hematocrit (28.72 ± 12.86 versus 37.67 ± 8.90%, P < .001), hemoglobin and creatinine concentration. Conclusions and Clinical Importance: Hematologic abnormalities are common in FeLV‐infected but not in FIV‐infected cats. Clinicopathologic abnormalities are less frequent in FIV‐infected cats and might reflect an unspecific immunologic response.     

EFFECT OF VENTILATION TECHNIQUE AND AIRWAY DIAMETER ON BRONCHIAL LUMEN TO PULMONARY ARTERY DIAMETER RATIOS IN CLINICALLY NORMAL BEAGLE DOGS

In dogs, a mean broncho‐arterial ratio of 1.45 ± 0.21 has been previously defined as normal. These values were obtained in dogs under general inhalational anesthesia using a single breath‐hold technique. The purpose of the study was to determine whether ventilation technique and bronchial diameter have an effect on broncho‐arterial ratios. Four healthy Beagle dogs were scanned twice, each time with positive‐pressure inspiration and end expiration. For each ventilation technique, broncho‐arterial ratios were grouped into those obtained from small or large bronchi using the median diameter of the bronchi as the cutoff value. Mean broncho‐arterial ratios obtained using positive‐pressure inspiration (1.24 ± 0.23) were statistically greater than those obtained at end expiration (1.11 ± 0.20) P = 0.005. There was a strong positive correlation between bronchial diameter and broncho‐arterial ratios for both ventilation techniques (positive‐pressure inspiration r_s = .786, P < 0.0005 and end expiration r_s = .709, P < 0.0005). Mean broncho‐arterial ratio for the large bronchi obtained applying positive‐pressure inspiration was 1.39 cm ± 0.20 and during end expiration was 1.22 cm ± 0.20. Mean broncho‐arterial ratio for the small bronchi obtained during positive‐pressure inspiration was 1.08 cm ± 0.13 and during end expiration was 1.01 cm ± 0.13. There was a statistically significant difference between these groups (F = 248.60, P = 0.005). Findings indicated that reference values obtained using positive‐pressure inspiration or from the larger bronchi may not be applicable to dogs scanned during end expiration or to the smaller bronchi.     

Effect of experimental endotoxemia on thrombelastography parameters, secondary and tertiary hemostasis in dogs

Background: Thrombelastography (TEG) and indicators of secondary and tertiary hemostasis might be altered in dogs with endotoxemia. Hypothesis: Endotoxemia influences measures of coagulation in dogs. Animals: Ten healthy cross‐bred dogs. Material and Methods: Prospective laboratory study between controls (n = 5) receiving 0.9% saline IV and the study group (n = 5) treated with low‐dose lipopolysaccharide (0.02 mg/kg IV). Physical examination and sampling for measurement of leukocytes, platelets, and coagulation variables were performed at time points 0, 1, 4, and 24 hours. Coagulation variables included kaolin‐activated TEG, 1‐stage prothrombin time (OSPT), activated partial thromboplastin time (aPTT), fibrinogen, factor VIII, antithrombin, protein C, protein S, activated protein C (APC)‐ratio calculated from aPTT with and without presence of APC), and D‐Dimers. Results: Endotoxemia‐induced clinical signs included lethargy (n = 5/5), diarrhea (n = 4/5), emesis (n = 4/5), and abdominal pain (2/5). After 1 hour there was severe leukopenia (2.5 ± 0.7 × 10⁹/L; mean ± SD, P < .0001) and a 2.2‐fold increase in D‐Dimers (0.81 ± 0.64 mg/L, P < .0001). After 4 hours there was hyperthermia (40.3 ± 0.4°C, P < .0001) and increases in OSPT (10.5 ± 2.7 seconds, P < .0001), aPTT (16.7±5.2 seconds, P= 0.002). A significant decrease in fibrinogen (1.5±1.0 g/L, P= 0.001), protein C (31 ± 33%, P <.0001), protein S (63 ± 47%, P < .0001), TEG α (58 ± 19, P= .007), and TEG maximal amplitude (50 ± 19 mm, P= .003) was seen compared with the controls. APC‐ratio rose significantly (2.5 ± 0.2, P < .0001) without exceeding the reference interval (n = 4/5). Conclusion and Clinical Importance: D‐Dimers are the earliest indicator for endotoxemia‐associated coagulation abnormalities followed by decreased protein C concentration. APC‐ratio and TEG were not good screening variables.     

Hemodynamic,respiratory and sedative effects of progressively increasing doses of acepromazine in conscious dogs

ObjectiveTo evaluate the effects of progressively increasing doses of acepromazine on cardiopulmonary variables and sedation in conscious dogs.Study designProspective, experimental study.AnimalsA group of six healthy, adult, mixed-breed dogs weighing 16.5 ± 5.0 kg (mean ± standard deviation).MethodsDogs were instrumented with thermodilution and arterial catheters for evaluation of hemodynamics and arterial blood gases. On a single occasion, acepromazine was administered intravenously to each dog at 10, 15, 25 and 50 μg kg^–1 at 20 minute intervals, resulting in cumulative acepromazine doses of 10 μg kg^–1 (ACP₁₀), 25 μg kg^–1 (ACP₂₅), 50 μg kg^–1 (ACP₅₀) and 100 μg kg^–1 (ACP₁₀₀). Hemodynamic data and sedation scores were recorded before (baseline) and 20 minutes after each acepromazine dose.ResultsCompared with baseline, all acepromazine doses significantly decreased stroke index (SI), mean arterial pressure (MAP) and arterial oxygen content (CaO₂) with maximum decreases of 16%, 17% and 21%, respectively. Cardiac index (CI) decreased by up to 19% but not significantly. Decreases of 26–38% were recorded for oxygen delivery index (DO₂I), with significant differences for ACP₅₀ and ACP₁₀₀. Systemic vascular resistance index (SVRI) and heart rate did not change significantly. No significant difference was found among acepromazine doses for hemodynamic data. After ACP₁₀, mild sedation was observed in five/six dogs and moderate sedation in one/six dogs, whereas after ACP₂₅, ACP₅₀ and ACP₁₀₀, moderate sedation was observed in five/six or six/six dogs.Conclusions and clinical relevanceIn conscious dogs, acepromazine decreased MAP, SI, CaO₂ and DO₂I, but no significant dose effect was detected. SVRI was not significantly changed, suggesting that the reduction in MAP resulted from decreased CI. The ACP₂₅, ACP₅₀ and ACP₁₀₀ doses resulted in moderate sedation in most dogs; ACP₁₀ resulted in only mild sedation.     

EFFECTS OF INTRAVENOUS DEXMEDETOMIDINE ON CARDIAC CHARACTERISTICS MEASURED USING RADIOGRAPHY AND ECHOCARDIOGRAPHY IN SIX HEALTHY DOGS

Dexmedetomidine is a highly specific and selective α2‐adrenergic receptor agonist widely used in dogs for sedation or analgesia. We hypothesized that dexmedetomidine may cause significant changes in radiographic and echocardiographic measurements. The objective of this prospective cross‐sectional study was to test this hypothesis in a sample of six healthy dogs. Staff‐owned dogs were recruited and received a single dose of dexmedetomidine 250 μg/m² intravenously. Thoracic radiography and echocardiography were performed 1 h before treatment, and repeated 10 and 30 min after treatment, respectively. One observer recorded cardiac measurements from radiographs and another observer recorded echocardiographic measurements. Vertebral heart score and cardiac size to thorax ratio on the ventrodorsal projection increased from 9.8 ± 0.6 v to 10.3 ± 0.7 v (P = 0.0007) and 0.61 ± 0.04 to 0.68 ± 0.03 (P = 0.0109), respectively. E point‐to‐septal separation and left ventricle internal diameter in diastole and systole increased from 2.4 ± 1.1 to 6.6 ± 1.9 mm, 32.3 ± 8.1 to 35.5 ± 8.8 mm, and 19.4 ± 6 to 27.0 ± 7.2 mm, respectively (P < 0.05). Fractional shortening and sphericity index decreased from 40.7 ± 5.8 to 24.4 ± 2.9%, and 1.81 ± 0.07 to 1.58 ± 0.04, respectively (P < 0.05). Moderate‐to‐severe mitral regurgitation and mild pulmonic regurgitation occurred in all dogs after dexmedetomidine administration. Findings indicated that dexmedetomidine could cause false‐positive diagnoses of valvular regurgitation and cardiomegaly in dogs undergoing thoracic radiography and echocardiography.     

Estimated plasma bupivacaine concentration after single dose and eight-hour continuous intra-articular infusion of bupivacaine in normal dogs

Objective— To estimate maximum plasma concentration (C_max) and time to maximum plasma (t_max) bupivacaine concentration after intra‐articular administration of bupivacaine for single injection (SI) and injection followed by continuous infusion (CI) in normal dogs. Study Design— Cross‐over design with a 2‐week washout period. Animals— Healthy Coon Hound dogs (n=8). Methods— Using gas chromatography/mass spectrometry, canine plasma bupivacaine concentration was measured before and after SI (1.5 mg/kg) and CI (1.5 mg/kg and 0.3 mg/kg/h). Software was used to establish plasma concentration–time curves and estimate C_max, T_max and other pharmacokinetic variables for comparison of SI and CI. Results— Bupivacaine plasma concentration after SI and CI best fit a 3 exponential model. For SI, mean maximum concentration (C_max, 1.33±0.954 μg/mL) occurred at 11.37±4.546 minutes. For CI, mean C_max (1.13±0.509 μg/mL) occurred at 10.37±4.109 minutes. The area under the concentration–time curve was smaller for SI (143.59±118.390 μg/mL × min) than for CI (626.502±423.653 μg/mL × min, P=.02) and half‐life was shorter for SI (61.33±77.706 minutes) than for CI (245.363±104.415 minutes, P=.01). The highest plasma bupivacaine concentration for any dog was 3.2 μg/mL for SI and 2.3 μg/mL for CI. Conclusion— Intra‐articular bupivacaine administration results in delayed absorption from the stifle into the systemic circulation with mean C_max below that considered toxic and no systemic drug accumulation. Clinical Relevance— Intra‐articular bupivacaine can be administered with small risk of reaching toxic plasma concentrations in dogs, though toxic concentrations may be approached. Caution should be exercised with multimodal bupivacaine administration because plasma drug concentration may rise higher than with single intra‐articular injection.     

RADIOGRAPHIC LIVER SIZE IN PEKINGESE DOGS VERSUS OTHER DOG BREEDS

Differential diagnoses for canine liver disease are commonly based on radiographic estimates of liver size, however little has been published on breed variations. Aims of this study were to describe normal radiographic liver size in Pekingese dogs and to compare normal measurements for this breed with other dog breeds and Pekingese dogs with liver disease. Liver measurements were compared for clinically normal Pekingese (n = 61), normal non‐Pekingese brachycephalic (n = 45), normal nonbrachycephalic (n = 71), and Pekingese breed dogs with liver disease (n = 22). For each dog, body weight, liver length, T11 vertebral length, thoracic depth, and thoracic width were measured on right lateral and ventrodorsal abdominal radiographs. Liver volume was calculated using a formula and ratios of liver length/T11 vertebral length and liver volume/body weight ratio were determined. Normal Pekingese dogs had a significantly smaller liver volume/body weight ratio (16.73 ± 5.67, P < 0.05) than normal non‐Pekingese brachycephalic breed dogs (19.54 ± 5.03) and normal nonbrachycephalic breed dogs (18.72 ± 6.52). The liver length/T11 vertebral length ratio in normal Pekingese (4.64 ± 0.65) was significantly smaller than normal non‐Pekingese brachycephalic breed dogs (5.16 ± 0.74) and normal nonbrachycephalic breed dogs (5.40 ± 0.74). Ratios of liver volume/body weight and liver length/T11 vertebral length in normal Pekingese were significantly different from Pekingese with liver diseases (P < 0.05). Findings supported our hypothesis that Pekingese dogs have a smaller normal radiographic liver size than other breeds. We recommend using 4.64× the length of the T11 vertebra as a radiographic criterion for normal liver length in Pekingese dogs.     

The cardiopulmonary effects of a peripheral alpha‐2‐adrenoceptor antagonist,MK‐467, in dogs sedated with a combination of medetomidine and butorphanol

ObjectiveTo compare the cardiopulmonary effects of intravenous (IV) and intramuscular (IM) medetomidine and butorphanol with or without MK-467.Study designProspective, randomized experimental cross-over.AnimalsEight purpose–bred beagles (two females, six males), 3–4 years old and weighing 14.5 ±1.6 kg (mean ± SD).MethodsAll dogs received four different treatments as follows: medetomidine 20 μg kg^?1 and butorphanol tartrate 0.1 mg kg^?1 IV and IM (MB), and MB combined with MK-467,500 μg kg^?1 (MBMK) IV and IM. Heart rate (HR), arterial blood pressures (SAP, MAP, DAP), central venous pressure (CVP), cardiac output, respiratory rate (f_R), rectal temperature (RT) were measured and arterial blood samples were obtained for gas analysis at baseline and at 3, 10, 20, 30, 45 and 60 minutes after drug administration. The cardiac index (CI), systemic vascular resistance index (SVRI) and oxygen delivery index (DO₂I) were calculated. After the follow-up period atipamezole 50 μg kg^?1 IM was given to reverse sedation.ResultsHR, CI and DO₂I were significantly higher with MBMK after both IV and IM administration. Similarly, SAP, MAP, DAP, CVP, SVRI and RT were significantly lower after MBMK than with MB. There were no differences in f_R between treatments, but arterial partial pressure of oxygen decreased transiently after all treatments. Recoveries were uneventful following atipamezole administration after all treatments.Conclusions and clinical relevanceMK-467 attenuated the cardiovascular effects of a medetomidine-butorphanol combination after IV and IM administration.     

WHICH AIRWAY PRESSURE SHOULD BE APPLIED DURING BREATH‐HOLD IN DOGS UNDERGOING THORACIC COMPUTED TOMOGRAPHY?

This randomized controlled trial study aimed to identify the optimal positive pressure (PP) level that can clear atelectasis while avoiding pulmonary hyperinflation during the breath‐hold technique in dogs undergoing thoracic computed tomography (CT). Sixty dogs affected by mammary tumors undergoing thoracic CT for the screening of pulmonary metastases were randomly assigned to six groups with different levels of PP during the breath‐hold technique: 0 (control), 5 (PP5), 8 (PP8), 10 (PP10), 12 (PP12), and 15 (PP15) cmH₂O. The percentage of atelectatic lung region was lower in the PP10 (3.7 ± 1.1%; P = 0.002), PP12 (3.4 ± 1.3%; P = 0.0001), and PP15 (2.8 ± 0.9%; P = 0.006) groups than in the control group (5.0 ± 2.3%), and the percentage of poorly aerated lung region was lower in the PP8 (15.1 ± 2.6%; P = 0.0009), PP10 (13.0 ± 2.0 %; P = 0.002), PP12 (13.0 ± 2.2 %; P = 0.0002), and PP15 (11.1 ± 1.9%; P = 0.0002) groups than in the control group (19.8 ± 5.0). The percentage of normally aerated lung region, however, was higher in the PP10 (79.7 ± 4.1%; P = 0.005), PP12 (79.8 ± 5.1%; P = 0.0002), and PP15 (80.2 ± 4.9%; P = 0.002) groups than in the control group (73.4 ± 6.6%). A PP of 10–12 cmH₂O during the breath‐hold technique should be considered to improve lung aeration during a breath‐hold technique in dogs undergoing thoracic CT.     

Hounsfield units are a useful predictor of pleural effusion cytological type in dogs but not in cats

All categories of pleural effusion subjectively display as soft tissue opacity on computed tomography (CT). Quantitative measurement using Hounsfield units (HU) has the potential to bring additional information regarding the nature of the fluid in a noninvasive way. The purposes of this retrospective cross‐sectional analytical study were to compare Hounsfield units of different pleural effusion categories in dogs and cats, assess association between specific cytologic parameters and Hounsfield units, and evaluate the effect of dependent vs. nondependent aspect of the effusion pool on Hounsfield unit. A total of 111 patients (74 dogs and 37 cats) with pleural effusion, that underwent thoracic CT and diagnostic thoracocentesis, were included in the study. Effusions were cytologically categorized as exudate, transudate, modified transudate, hemorrhage, or chyle. Significant differences existed in Hounsfield units between categories in dogs (P < 0.0001) but not in cats (P = 0.334). Canine chylous effusion (6.1 ± 4.7 HU (mean ± standard deviation)) and transudate (5.6 ± 2.0) were significantly lower than exudate (20.3 ± 9.5) and hemorrhage (21.4 ± 9.2). No significant differences were found between modified transudate (13.6 ± 10.3) and other categories. Significant, weak linear correlation was identified in dogs between Hounsfield units and total protein (P = 0.018, R² = 0.089), red blood cells (P = 0.021, R² = 0.077), and total nucleated cells (P = 0.013, R² = 0.089). The Hounsfield units of dependent effusion was not significantly higher than the nondependent effusion, except for canine chylous effusion (P = 0.008). Fourteen Hounsfield units was identified as the most clinically useful threshold: <14 HU identified transudate or chylous effusion with a sensitivity of 100% and a specificity of 69%. A threshold >14 HU had a specificity of 100% and a sensitivity of 69% for identifying exudate, modified transudate, or hemorrhage.     

Renal resistive index in 55 dogs with degenerative mitral valve disease

Background

Azotemia occurs frequently in dogs with degenerative mitral valve disease (DMVD). It could indicate changes in renal hemodynamics.

Hypothesis/Objectives

To assess the renal resistive index (RI) in dogs with DMVD, and the statistical link between heart failure class, azotemia, echo‐Doppler parameters, several plasma variables, and RI.

Animals

Fifty‐five dogs with naturally occurring DVMD were used (ISACHC class 1 [n = 28], 2 [n = 19], and 3 [n = 8]).

Methods

Observational, blinded study, performed under standardized conditions. Physical examination, renal ultrasonography, and echo‐Doppler examinations were performed in awake dogs. The RI of the renal, interlobar, and arcuate arteries were measured. Plasma creatinine, urea, and N‐terminal pro‐B‐type natriuretic peptide concentrations (NT‐proBNP) were determined. Statistical links between variables and RI were tested by means of a general linear model.

Results

Although the RI of renal and arcuate arteries were unaffected by ISACHC class, the left interlobar RI increased (P < .001) from 0.62 ± 0.05 (mean ± SD) in class 1 to 0.76 ± 0.08 in class 3. It was also higher (P < .001) in azotemic (0.74 ± 0.08) than in non‐azotemic (0.62 ± 0.05) dogs. Similar findings were observed for right interlobar RI. Univariate analysis showed a positive statistical link between NT‐proBNP (P = .002), urea (P < .001), creatinine (P = .002), urea‐to‐creatinine ratio (P < .001), left atrium‐to‐aorta ratio (P < .001), regurgitation fraction (P < .001), systolic pulmonary arterial pressure (P < .001), shortening fraction (P = .035), and RI.

Conclusion and Clinical Importance

In dogs with DMVD, interlobar RI increases with heart failure severity and azotemia but a cause and effect relationship remains to be established.     

The effect of a single dose of topical 0.005% latanoprost and 2% dorzolamide/0.5% timolol combination on the blood-aqueous barrier in dogs: a pilot study

Objective To determine the effects of 0.005% latanoprost and 2% dorzolamide/0.5% timolol on the blood‐aqueous barrier (BAB) in normal dogs. Animals studied Eight mixed‐breed and pure‐breed dogs. Procedures Baseline anterior chamber fluorophotometry was performed on eight normal dogs. Sodium fluorescein was injected and the dogs were scanned 60–90 min post‐injection. Seventy‐two hours following the baseline scan, one eye received one drop of latanoprost. Fluorophotometry was repeated 4 h after drug administration. Following a washout period, the identical procedure was performed 4 h after the administration of dorzolamide/timolol. The degree of BAB breakdown was determined by comparing the concentrations of fluorescein within the anterior chamber before and after drug administration. BAB breakdown was expressed as a percentage increase in the post‐treatment fluorescein concentration over the baseline concentration: %INC [Fl] = {([Fl]_post – [Fl]_baseline)/[Fl]_baseline} × 100. The percentage increase in fluorescein concentration in the treated eye was compared to that in the nontreated eye using a paired t‐test with significance set at P ≤ 0.05. Results Following administration of latanoprost, the fluorescein in the treated eyes increased 49% (± 58%) from baseline compared to 10% (± 31%) in the untreated eyes (P = 0.016). Following administration of dorzolamide/timolol, the fluorescein concentration increased 38% (± 54%) compared to baseline vs. 24% (± 38%) in the untreated eyes (P = 0.22). Conclusions The results of this study show that topical latanoprost may cause BAB disruption in normal dogs while topical dorzolamide/timolol may have no effect on the BAB in normal dogs.     

Electroretinography in the western gray kangaroo (Macropus fuliginosus)

Objective To perform electroretinography on normal anesthetized western gray kangaroos (Macropus fuliginosus). Animals studied Six captive western gray kangaroos. Procedures The kangaroos were anesthetized using a combination of ketamine and medetomidine via a remote drug delivery system, then were maintained on isoflurane after endotracheal intubation and reversal of the medetomidine with atipamazole. After a minimum of 20 min of dark adaptation, electroretinograms were obtained using a handheld electroretinography (ERG) machine using a single flash protocol at three light intensities: 10 mcd.s/m², 3000 mcd.s/m², 10 000 mcd.s/m². Results At 10 mcd.s/m² the mean b‐wave amplitude and implicit time was 102.0 μV (SD ± 41.3 and 95% CI 68.9–135.1) and 78.4 ms (SD ± 8.3 and 95% CI 71.8–85.0). At 3000 mcd.s/m² the mean a‐wave amplitude and implicit time was 69.9 μV (SD ± 20.5 and 95% CI 53.5–86.3) and 17.6 ms (SD ± 1.5 and 95% CI 16.4–18.8) and the mean b‐wave amplitude and implicit time was 175.4 μV (SD ± 35.9 and 95% CI 146.7–204.1) and 74.1 ms (SD ± 3.5 and 95% CI 71.2–76.9). At 10 000 mcd.s/m² the mean a‐wave amplitude and implicit time was 89.1 μV (SD ± 27.1 and 95% CI 67.5–110.8) and 16.8 ms (SD ± 1.0 and 95% CI 16.0–17.0) and the mean b‐wave amplitude and implicit time was 203.7 μV (SD ± 41.4 and 95% CI 170.6–236.8) and 75.4 ms (SD ± 3.3 and 95% CI 72.8–78.1). Conclusion Electroretinography outside of the typical clinical setting is feasible using a portable ERG system and allows for quick analysis of retinal function in exotic species.     

Indication,management, and outcome of brachycephalic dogs requiring mechanical ventilation

Objectives – To evaluate the frequency, and need for mechanical ventilation (MV) in a population of brachycephalic dogs (BD) compared with non‐BD. Also, to describe the pre‐MV abnormalities, ventilator settings used, the cardiovascular and pulmonary monitoring results and complications encountered in the same BD population. In addition, we sought to identify factors associated with successful weaning and describe outcomes of BD requiring MV. Design – Retrospective observational study (1990–2008). Setting – University Small Animal Teaching Hospital. Animals – Fifteen BD managed with MV. Interventions – None. Measurements and Main Results – Signalment, indication for MV, ventilator settings, arterial blood gas values, duration of MV, complications, and outcome were recorded for each patient enrolled in study. BD were more likely to receive MV than non‐BD (P=0.036). Out of the 15 dogs that fulfilled the inclusion criteria 7 (47%) underwent MV for impending respiratory fatigue, 6 (40%) for hypoxemia and 2 for hypercapnea. The most common underlying disease was aspiration pneumonia. Duration of MV ranged from 2 to 240 hours (median 15 hours). Seven patients were weaned (47%). Seven dogs had a temporary tracheostomy tube and 5 of them (71%) were weaned. Dogs that were weaned had a significantly greater preweaning trial PaO₂/FiO₂ ratio than those that were not (359 ± 92 versus 210 ± 57 mm Hg, P=0.025). No significant difference for weaning success between dogs with and those without a tracheostomy was detected (P=0.132). The discharge rate was 27% (all from the respiratory fatigue group). Conclusion – Among all dogs admitted to ICU, BD were more likely to receive MV than non‐BD. Aspiration pneumonia was frequently identified as the underlying cause of respiratory compromise. The survival rate for BD undergoing MV was not markedly different from previous studies. Weaning of BD from MV may be facilitated by employing preemptive strategies such as performing tracheostomy tube placements.