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- Author or Editor: Barret J. Bulmer x
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Abstract
Objective—To validate the use of a human enzyme immunoassay (EIA) kit for measurement of plasma antidiuretic hormone (ADH) concentration in dogs and evaluate plasma ADH concentrations in dogs with congestive heart failure (CHF) attributable to acquired cardiac disease, compared with findings in healthy dogs.
Animals—6 healthy dogs and 12 dogs with CHF as a result of chronic degenerative valve disease or dilated cardiomyopathy.
Procedures—Plasma samples from the 6 healthy dogs were pooled and used to validate the EIA kit for measurement of plasma ADH concentration in dogs by assessing intra-assay precision, dilutional linearity, and spiking recovery. Following validation, plasma ADH concentrations were measured in the 6 healthy dogs and in the 12 dogs with CHF for comparison.
Results—The EIA kit measured ADH concentrations in canine plasma samples with acceptable intra-assay precision, dilutional linearity, and spiking recovery. The intra-assay coefficient of variation was 11%. By use of this assay, the median plasma concentration of ADH in dogs with CHF was 6.15 pg/mL (SD, 3.2 pg/mL; range, 4.18 to 15.47 pg/mL), which was significantly higher than the median concentration in healthy dogs (3.67 pg/mL [SD, 0.93 pg/mL; range, 3.49 to 5.45 pg/mL]).
Conclusions and Clinical Relevance—Plasma ADH concentrations in dogs can be measured with the tested EIA kit. Plasma ADH concentrations were higher in dogs with CHF induced by acquired cardiac disease than in healthy dogs. This observation provides a basis for future studies evaluating circulating ADH concentrations in dogs with developing heart failure.
Abstract
Objective—To describe echocardiographic findings in dogs with dysautonomia.
Design—Prospective case series.
Animals—20 dogs with dysautonomia (13 confirmed during necropsy and 7 with results of antemortem testing [tear production, pilocarpine response test, atropine response test, and ID histamine response] supportive of the diagnosis).
Procedures—Dogs with dysautonomia were evaluated by use of echocardiography, and M-mode measurements were obtained on all dogs. A dobutamine response test was performed on 1 dog, starting at a rate of 1 μg/kg/min and doubling the rate every 15 minutes until fractional shortening (FS) increased to > 2 times the baseline value.
Results—Evidence of systolic dysfunction was detected in 17 of 20 dogs with dysautonomia, as determined on the basis of FS (median, 17.9%; range, 4.0% to 31.1%). Left ventricular internal dimension during diastole or left ventricular internal dimension during systole was enlarged in 4 of 20 and 14 of 20 dogs, respectively. Enlargement of the left atrium or aorta was identified in 3 of 15 and 1 of 15 dogs in which it was measured, respectively. Administration of dobutamine at a rate of 4 μg/kg/min resulted in dramatic improvement in FS (increase from 4% to 17%) in the 1 dog tested.
Conclusions and Clinical Relevance—Results suggested that echocardiographic evidence of diminished systolic function was common in dogs with dysautonomia. Whether the diminished function was a result of sympathetic denervation or myocardial hibernation was unclear, although myocardial hibernation was more likely.
Abstract
Objective—To evaluate the cardiovascular effects of the α2-adrenergic receptor agonist medetomidine hydrochloride in clinically normal cats.
Animals—7 clinically normal cats.
Procedure—Cats were anesthetized with isoflurane, and thermodilution catheters were placed for measurement of central venous, pulmonary, and pulmonary capillary wedge pressures and for determination of cardiac output. The dorsal pedal artery was catheterized for measurement of arterial blood pressures and blood gas tensions. Baseline variables were recorded, and medetomidine (20 µg/kg of body weight, IM) was administered. Hemodynamic measurements were repeated 15 and 30 minutes after medetomidine administration.
Results—Heart rate, cardiac index, stroke index, ratepressure product, and right and left ventricular stroke work index significantly decreased from baseline after medetomidine administration, whereas systemic vascular resistance and central venous pressure increased. However, systolic, mean, and diastolic arterial pressures as well as arterial pH, and oxygen and carbon dioxide tensions were not significantly different from baseline values.
Conclusions and Clinical Relevance—When administered alone to clinically normal cats, medetomidine (20 µg/kg, IM) induced a significant decrease in cardiac output, stroke volume, and heart rate. Arterial blood pressures did not increase, which may reflect a predominant central α2-adrenergic effect over peripheral vascular effects. (Am J Vet Res 2001;62:1745–1762)
Abstract
Objective—To evaluate the effects of medetomidine on dynamic left ventricular outflow tract (LVOT) obstruction in cats with left ventricular hypertrophy.
Design—Clinical trial.
Animals—6 domestic shorthair cats with echocardiographic evidence of dynamic LVOT obstruction.
Procedure—Cats were restrained in lateral recumbency, and baseline M-mode and Doppler echocardiographic examinations were performed. An ECG was recorded continuously, and blood pressure was measured indirectly with Doppler instrumentation. Medetomidine (20 µg/kg [9.1 µg/lb]) was then administered IM, and examinations were repeated 15 minutes later.
Results—Significant decreases in heart rate, LVOT velocity, and the LVOT pressure gradient were documented following medetomidine administration. After adjusting for the effects of heart rate by ANCOVA, there were no significant differences in any other systolic or diastolic indices of left ventricular function.
Conclusions and Clinical Relevance—Results suggest that administration of medetomidine to cats with dynamic LVOT obstruction may result in elimination of outflow tract obstruction; medetomidine may be a suitable sedative and analgesic agent in this subpopulation of cats. (J Am Vet Med Assoc 2002;221:1276–1281)
Abstract
Objective—To determine the hemodynamic consequences of the coadministration of a continuous rate infusion (CRI) of medetomidine with a fentanyl bolus in dogs.
Animals—12 healthy sexually intact male dogs weighing 30.3 ± 4.2 kg (mean ± SD).
Procedure—Dogs received either fentanyl alone (15.0 µg/kg, IV bolus) or the same dose of fentanyl during an 11-hour CRI of medetomidine (1.5 µg/kg/h, IV). Prior to drug administration, dogs were instrumented for measurement of cardiac output, left atrial pressure, and systemic arterial blood pressures. Additionally, blood samples were collected from the pulmonary artery and left atrium for blood gas analysis.
Results—Medetomidine infusion reduced the cardiac index, heart rate, and O2 delivery while increasing left atrial pressure. Subsequent fentanyl administration further decreased the cardiac index. The PaO2 was not significantly different between the 2 treatment groups; however, fentanyl transiently decreased PaO2 from baseline values in dogs receiving a CRI of medetomidine.
Conclusions and Clinical Relevance—Because of the prolonged hemodynamic changes associated with the CRI of medetomidine, its safety should be further evaluated before being clinically implemented in dogs. (Am J Vet Res 2005;66:1222–1226)
Abstract
Objective—To develop, validate, and evaluate a questionnaire (Cats’ Assessment Tool for Cardiac Health [CATCH] questionnaire) for assessing health-related quality of life in cats with cardiac disease.
Design—Prospective study.
Animals—275 cats with cardiac disease.
Procedures—The questionnaire was developed on the basis of clinical signs of cardiac disease in cats. A CATCH score was calculated by summing responses to questionnaire items; possible scores ranged from 0 to 80. For questionnaire validation, owners of 75 cats were asked to complete the questionnaire (10 owners completed the questionnaire twice). Disease severity was assessed with the International Small Animal Cardiac Health Council (ISACHC) classification for cardiac disease. Following validation, the final questionnaire was administered to owners of the remaining 200 cats.
Results—Internal consistency of the questionnaire was good, and the CATCH score was significantly correlated with ISACHC classification. For owners that completed the questionnaire twice, scores were significantly correlated. During the second phase of the study, the CATCH score ranged from 0 to 74 (median, 7) and was significantly correlated with ISACHC classification.
Conclusions and Clinical Relevance—Results suggested that the CATCH questionnaire is a valid and reliable method for assessing health-related quality of life in cats with cardiac disease. Further research is warranted to test the tool's sensitivity to changes in medical treatment and its potential role as a clinical and research tool.
Abstract
Objective—To determine whether serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration is useful in discriminating between cardiac and noncardiac (ie, primary respiratory tract disease) causes of respiratory signs (ie, coughing, stertor, stridor, excessive panting, increased respiratory effort, tachypnea, or overt respiratory distress) in dogs.
Design—Multicenter cross-sectional study.
Animals—115 dogs with respiratory signs.
Procedures—Dogs with respiratory signs were solicited for study. Physical examination, thoracic radiography, and echocardiography were used to determine whether respiratory signs were the result of cardiac (ie, congestive heart failure) or noncardiac (ie, primary respiratory tract disease) causes. Serum samples for NT-proBNP assay were obtained at time of admission for each dog. Receiver-operating characteristic curves were constructed to determine the ability of serum NT-proBNP concentration to discriminate between cardiac and noncardiac causes of respiratory signs.
Results—Serum NT-proBNP concentration was significantly higher in dogs with cardiac versus noncardiac causes of respiratory signs. In dogs with primary respiratory tract disease, serum NT-proBNP concentration was significantly higher in those with concurrent pulmonary hypertension than in those without. A serum NT-proBNP cutoff concentration > 1,158 pmol/L discriminated between dogs with congestive heart failure and dogs with primary respiratory tract disease with a sensitivity of 85.5% and a specificity of 81.3%.
Conclusions and Clinical Relevance—Measuring serum NT-proBNP concentration in dogs with respiratory signs helps to differentiate between congestive heart failure and primary respiratory tract disease as an underlying cause.
