Search Results

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

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 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

Objective—To evaluate the effects of positioning and number of repeated measurements on intra- and interobserver variability of echocardiographic measurements in dogs.

Design—Prospective study.

Animals—4 healthy dogs.

Procedure—Each observer performed 24 examinations, separately assessing each dog 6 nonconsecutive times (3 times with the dog in lateral recumbency and 3 with the dog in a standing position). Variables evaluated included M-mode measurements of left ventricular end-diastolic and left ventricular endsystolic diameters, left ventricular free-wall thickness in diastole and systole, interventricular septal thickness in diastole and systole, left ventricular shortening fraction, and 2-dimensional measurements of the left atrial diameter-to-aortic diameter ratio.

Results—All coefficients of variation (range, 3.4% to 26.6%) were similar between operators and positions and were < 15% for 27 of 32 values. For both operators, repeatability of the measurements was better for left ventricular end-systolic diameter, left ventricular free-wall thickness in diastole, left ventricular freewall thickness in systole, and the left atrial diameterto- aortic diameter in the standing position, and similar for both positions for shortening fraction and left ventricular end-diastolic diameter. No effect of cardiac cycle was observed.

Conclusions and Clinical Relevance—Within-day variability of conventional echocardiography performed with the dog in the standing position was at least as good as that obtained with the dog in lateral recumbency for most measured variables. Single measurements of each variable may be sufficient for trained observers examining dogs that do not have an arrhythmia. The standing position should be used, particularly for stressed or dyspneic dogs. (J Am Vet Med Assoc 2005;227:743–747)