Search Results

Abstract

Objective—To evaluate the effect of dilated cardiomyopathy (DCM) on activity of the reninangiotensin- aldosterone system (RAAS), the N-terminal fragment of proatrial natriuretic peptide (NTproANP), and thyroid hormone concentrations in dogs.

Animals—15 dogs with clinical signs of DCM, 15 dogs without clinical signs of DCM, and 15 age-, breed-, and sex-matched control dogs.

Procedure—Physical examinations, thoracic radiography, ECG, and echocardiography were performed on all dogs, and blood and urine samples were collected.

Results—Plasma renin activity (PRA), plasma aldosterone concentration (PAC), urine aldosterone-to-creatinine ratio, and NT-proANP concentrations were significantly increased in dogs with clinical signs of DCM, compared with dogs without clinical signs and control dogs. Thyroid-stimulating hormone and total thyroxine concentrations did not differ significantly among groups; however, free thyroxine (FT₄) concentrations were significantly decreased in dogs with clinical signs of DCM, compared with control dogs and DCM-dogs without clinical signs. Concentrations of PRA, PAC, FT₄, and urine aldosterone-to-creatinine ratio were significantly correlated, whereas plasma concentrations of NT-proANP only correlated with FT₄ concentration.

Conclusion and Clinical Relevance—In dogs with clinical signs of DCM, increased concentrations of components of the RAAS were associated with increased concentrations of NT-proANP. Analysis of the neurohormonal system may aid in identification of clinical stages of DCM for groups of dogs, but the range is too great and there are too many dogs that have neurohormonal concentrations within reference ranges to assess dogs on an individual basis. ( Am J Vet Res 2001;62:961–967)

Abstract

Objectives—To determine whether attenuated wavy fibers may be found in the myocardium of Newfoundlands without clinical or echocardiographic evidence of heart disease.

Animals—15 Newfoundlands from a kennel with a known predisposition to dilated cardiomyopathy (DCM) and 32 dogs of other breeds that died suddenly or were euthanatized for reasons unrelated to heart disease and did not have gross postmortem evidence of heart disease.

Procedure—Echocardiography was performed on all Newfoundlands on a yearly basis. Necropsy specimens from all dogs were evaluated for attenuated wavy fibers (ie, myocardial cells < 6 µm in diameter with a wavy appearance).

Results—None of the Newfoundlands had clinical signs of heart disease, and results of echocardiographic examinations were within reference ranges. Seven Newfoundlands had histologic evidence of attenuated wavy fibers, whereas attenuated wavy fibers were not found in the remaining 8 Newfoundlands or in any of the 32 dogs of other breeds.

Conclusions and Clinical Relevance—Findings suggest that attenuated wavy fibers in dogs with a known predisposition for DCM may indicate an early stage of the disease. However, further studies on a larger number of dogs are needed to confirm this hypothesis. (Am J Vet Res 2000;61:238-241)

Abstract

Objective—To evaluate plasma concentrations and urinary excretion of vasopressin and cortisol and urinary excretion of catecholamines in dogs with dilated cardiomyopathy (DCM).

Animals—15 dogs with clinical signs of DCM, 15 dogs with preclinical DCM, and 15 control dogs.

Procedure—Physical examinations, thoracic radiography, ECG, and echocardiography were performed on all dogs. Blood and urine samples were collected.

Results—Plasma concentration of vasopressin and the urine cortisol-to-urine creatinine ratio were significantly increased in dogs with clinical signs of DCM and dogs with preclinical DCM, compared with control dogs. Plasma vasopressin concentration was significantly higher in dogs with clinical signs of DCM, compared with dogs with preclinical DCM. Urine vasopressin-to-urine creatinine ratio was significantly increased in dogs with clinical signs of DCM, compared with dogs with preclinical DCM and control dogs. Urine epinephrine-to-urine creatinine ratio and urine norepinephrine-to-urine creatinine ratio were significantly increased in dogs with clinical signs of DCM, compared with control dogs. Plasma concentration of cortisol and urine dopamine-to-urine creatinine ratio did not differ significantly among groups.

Conclusions and Clinical Relevance—According to this study, the neuroendocrine pattern is changed in dogs with preclinical DCM. These changes are even more pronounced in dogs with clinical signs of DCM. Analysis of concentrations of vasopressin, cortisol, and catecholamines may aid in identification of the clinical stages of DCM. These findings may also provide a basis for additional studies of the possible beneficial effects of vasopressin antagonists and β-adrenergic receptor antagonists in the treatment of dogs with congestive heart failure and DCM. (Am J Vet Res 2005;66:1709–1717)

Abstract

Objective—To investigate the effects of IM administration of acepromazine on indices of relative renal blood flow and glomerular filtration rate (GFR) by means of scintigraphy, as well as the effects on physiologic, hematologic, and serum biochemical variables in anesthetized dogs, compared with effects of administration of saline.

Animals—6 healthy Beagles.

Procedure—Acepromazine (0.1 mg/kg) or physiologic saline (0.9 NaCl) solution was administered IM 30 minutes prior to induction of anesthesia with thiopentone; anesthesia was maintained with inspired isoflurane for 2.25 hours. Blood gases and circulatory and ventilatory variables were monitored. Renal function was evaluated by scintigraphic measurements of GFR and relative renal blood flow and analyses of serum and urine. Statistical analyses used ANOVA or Friedman ANOVA.

Results—Values of relative renal blood flow and GFR remained high despite low blood pressures. After administration of acepromazine, mean ± SD arterial blood pressure was 66 ± 8 mm Hg during anesthesia; this value was below the threshold (80 mm Hg) for renal autoregulation of GFR. In comparison, mean arterial blood pressure after administration of saline was significantly higher (87 ± 13 mm Hg). However, between treatments, there were no significant differences in GFR, relative renal blood flow, or other indices of renal function.

Conclusions and Clinical Relevance—Measurements of renal function and blood flow in dogs during anesthesia with thiopentone and isoflurane did not differ significantly between treatments, which suggested that acepromazine protects renal function despite inducing reduction in blood pressure, compared with effects of administration of saline. ( Am J Vet Res 2003; 64:590–598)

Abstract

Objective—To characterize sleeping respiratory rates (SRRs) and resting respiratory rates (RRRs), collected in the home environment, of dogs with subclinical heart disease that could result in left-sided congestive heart failure.

Design—Prospective cross-sectional study.

Animals—190 adult dogs with subclinical left-sided heart disease.

Procedures—Most dogs had mitral valve disease or dilated cardiomyopathy of various severities. Clients collected ten 1-minute SRRs or RRRs during a period ranging from 1 week to 6 months. Clinicians provided echocardiographic and medical data on each patient.

Results—The within-dog mean SRR (SRR_mean; 16 breaths/min) was significantly lower than the within-dog mean RRR (RRR_mean; 21 breaths/min). Seven dogs had SRR_mean and 33 dogs had RRR_mean > 25 breaths/min; 1 dog had SRR_mean and 12 dogs had RRR_mean > 30 breaths/min; these dogs mostly had a left atrial (LA)-to-aortic ratio > 1.8. Dogs with moderate LA enlargement had a significantly higher SRR_mean than did other dogs. However, median SRR_mean for each of 4 levels of LA enlargement was < 20 breaths/min; median RRR_mean for each of 4 levels of LA enlargement was < 25 breaths/min. Both within-dog SRR and RRR remained stable for 10 consecutive measurements. Treatment with cardiac medications or presence of pulmonary hypertension was not associated with SRR_mean or RRR_mean.

Conclusions and Clinical Relevance—Results suggested that dogs with confirmed subclinical left-sided heart disease of various severities generally had SRR_mean < 25 breaths/min, which was infrequently exceeded at any time, and that SRR and RRR remained stable, regardless of individual within-dog SRR_mean or RRR_mean. (J Am Vet Med Assoc 2013;243:839–843)

Abstract

Objective—To investigate effects of IV administered carprofen on indices of renal function and results of serum biochemical and hematologic analyses in dogs anesthetized with acepromazine-thiopentone-isoflurane that had low blood pressure during anesthesia.

Animals—6 healthy Beagles.

Procedure—A randomized crossover study was conducted, using the following treatments: saline (0.9% NaCl solution)-saline, saline-carprofen, and carprofensaline. Saline (0.08 ml/kg) and carprofen (4 mg/kg) were administered IV. The first treatment was administered 30 minutes before induction of anesthesia and immediately before administration of acepromazine (0.1 mg/kg, IM). Anesthesia was induced with thiopentone (25 mg/ml, IV) and maintained with inspired isoflurane (2% in oxygen). The second treatment was administered 30 minutes after onset of inhalation anesthesia. Blood gases, circulation, and ventilation were monitored. Renal function was assessed by glomerular filtration rate (GFR), using scintigraphy, serum biochemical analyses, and urinalysis. Hematologic analysis was performed. Statistical analysis was conducted, using ANOVA or Friedman ANOVA.

Results—Values did not differ significantly among the 3 treatments. For all treatments, sedation and anesthesia caused changes in results of serum biochemical and hematologic analyses, a decrease in mean arterial blood pressure to 65 mm Hg, an increase of 115 pmol/L in angiotensin II concentration, and an increase of 100 seconds in time required to reach maximum activity counts during scintigraphy.

Conclusions and Clinical Relevance—Carprofen administered IV before or during anesthesia did not cause detectable significant adverse effects on renal function or results of serum biochemical and hematologic analyses in healthy Beagles with low blood pressure during anesthesia. (Am J Vet Res 2002;63: 712–721)

Abstract

Objective—To investigate whether plasma activity of matrix metalloproteinase (MMP)-2 and -9 was associated with severity of myxomatous mitral valve disease (MMVD) in dogs and to assess potential associations between MMP activity and dog characteristics, echocardiographic variables, systolic arterial blood pressure (SAP), heart rate, cardiac troponin I (cTnI) concentration, and C-reactive protein concentration.

Animals—75 client-owned dogs.

Procedures—Severity of MMVD was assessed by use of echocardiography. Plasma activity of latent (pro-MMP) and active MMP-2 and -9 was analyzed via zymography. Plasma concentration of cTnI was analyzed with a high-sensitivity cTnI assay, and C-reactive protein concentration was analyzed with a canine-specific ELISA.

Results—Pro-MMP-9, active MMP-9, and pro-MMP-2 were detected, but active MMP-2 was not. No significant differences were found in MMP concentrations among the 4 MMVD severity groups. Activity of pro-MMP-9 decreased with decreases in SAP and was higher in male dogs than in female dogs. Activity of MMP-9 decreased with increases in left ventricular end-systolic dimension and with decreases in SAP and cTnI concentration. Left ventricular end-systolic dimension was the variable most strongly associated with MMP-9 activity. No associations were found between the activity of pro-MMP-2 and investigated variables.

Conclusions and Clinical Relevance—Plasma MMP-9 activity decreased with increases in the end-systolic left ventricular internal dimension and decreases in SAP. Hence, evaluation of MMP-9 activity has the potential to provide unique information about the myocardial remodeling process in dogs with MMVD.

Abstract

Objective—To investigate use of signal analysis of heart sounds and murmurs in assessing severity of mitral valve regurgitation (mitral regurgitation [MR]) in dogs with myxomatous mitral valve disease (MMVD).

Animals—77 client-owned dogs.

Procedures—Cardiac sounds were recorded from dogs evaluated by use of auscultatory and echocardiographic classification systems. Signal analysis techniques were developed to extract 7 sound variables (first frequency peak, murmur energy ratio, murmur duration > 200 Hz, sample entropy and first minimum of the auto mutual information function of the murmurs, and energy ratios of the first heart sound [S1] and second heart sound [S2]).

Results—Significant associations were detected between severity of MR and all sound variables, except the energy ratio of S1. An increase in severity of MR resulted in greater contribution of higher frequencies, increased signal irregularity, and decreased energy ratio of S2. The optimal combination of variables for distinguishing dogs with high-intensity murmurs from other dogs was energy ratio of S2 and murmur duration > 200 Hz (sensitivity, 79%; specificity, 71%) by use of the auscultatory classification. By use of the echocardiographic classification, corresponding variables were auto mutual information, first frequency peak, and energy ratio of S2 (sensitivity, 88%; specificity, 82%).

Conclusions and Clinical Relevance—Most of the investigated sound variables were significantly associated with severity of MR, which indicated a powerful diagnostic potential for monitoring MMVD. Signal analysis techniques could be valuable for clinicians when performing risk assessment or determining whether special care and more extensive examinations are required.

Abstract

Objective—To investigate effects of carprofen on indices of renal function and results of serum bio-chemical analyses and effects on cardiovascular variables during medetomidine-propofol-isoflurane anesthesia in dogs.

Animals—8 healthy male Beagles.

Procedures—A randomized crossover study was conducted with treatments including saline (0.9% NaCl) solution (0.08 mL/kg) and carprofen (4 mg/kg) administered IV. Saline solution or carprofen was administered 30 minutes before induction of anesthesia and immediately before administration of medetomidine (20 μg/kg, IM). Anesthesia was induced with propofol and maintained with inspired isoflurane in oxygen. Blood gas concentrations and ventilation were measured. Cardiovascular variables were continuously monitored via pulse contour cardiac output (CO) measurement. Renal function was assessed via glomerular filtration rate (GFR), renal blood flow (RBF), scintigraphy, serum biochemical analyses, urinalysis, and continuous CO measurements. Hematologic analysis was performed.

Results—Values did not differ significantly between the carprofen and saline solution groups. For both treatments, sedation and anesthesia caused changes in results of serum biochemical and hematologic analyses; a transient, significant increase in urine alkaline phosphatase activity; and blood flow diversion to the kidneys. The GFR increased significantly in both groups despite decreased CO, mean arterial pressure, and absolute RBF variables during anesthesia.

Conclusions and Clinical Relevance—Carprofen administered IV before anesthesia did not cause detectable, significant adverse effects on renal function during medetomidine-propofol-isoflurane anesthesia in healthy Beagles.

Abstract

Objective—To evaluate reproducibility of ejection fraction (EF), myocardial perfusion (MP), and pulmonary transit time (PTT) measured in a group of dogs by use of contrast echocardiography and to examine safety of this method by evaluating cardiac troponin I concentrations.

Animals—6 healthy dogs.

Procedures—2 bolus injections and a constant rate infusion of contrast agent were administered IV. Echocardiographic EF was determined by use of the area-length method and was calculated without and with contrast agent. The PTT and normalized PTT (PTT/mean R-R interval) were measured for each bolus. Constant rate infusion was used for global MP evaluation, and regional MP was calculated by use of a real-time method in 4 regions of interest of the left ventricle. Cardiac troponin I concentration was analyzed before and after contrast agent administration. Intraoberserver and interobserver variability was calculated.

Results—EF was easier to determine with the ultrasonographic contrast agent. For the first and second bolus, mean ± SD PTT was 1.8 ± 0.2 seconds and 2.1 ± 0.3 seconds and normalized PTT was 3.4 ± 0.3 seconds and 3.5 ± 0.3 seconds, respectively. A coefficient of variation < 15% was obtained for global MP but not for the regional MPs. No differences were detected between precontrast and postcontrast cardiac troponin I concentrations.

Conclusions and Clinical Relevance—Contrast echocardiography appeared to be a repeat-able and safe technique for use in the evaluation of global MP and PTT in healthy dogs, and it improved delineation of the endocardial border in dogs.