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Abstract

Objective—To evaluate the use of 24-hour ambulatory electrocardiography (AECG) for the detection of ventricular premature complexes (VPC) in healthy dogs.

Design—Case series.

Animals—50 healthy mature dogs.

Procedure—A 24-hour AECG was performed on each dog and evaluated for the presence of VPC.

Results—Fifty dogs weighing between 18.2 to 40.9 kg (40 and 90 lb) representing 13 breeds were evaluated; there were 4 sexually intact females, 21 spayed females, 4 sexually intact males, and 21 castrated males. Ages ranged from 1 to 12 years. Thirty-four dogs had no VPC; 16 dogs had between 1 and 24 VPC. The grade of arrhythmia ranged from 1 to 4, with 4 dogs having an arrhythmia with a grade > 1. Significant differences were not detected between the group of dogs with VPC and those without VPC with regard to sex, age, and minimum, maximum, or mean heart rate.

Conclusions and Clinical Relevance—We conclude that healthy mature dogs have infrequent VPC, as detected by use of 24-hour AECG. The presence of numerous or sequential VPC may be suggestive of cardiac or systemic disease and may indicate the need for thorough clinical evaluation. (J Am Vet Med Assoc 2001;218:1291–1292)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the use of in-hospital electrocardiography (ECG) for detection of ventricular premature complexes (VPC), compared with 24-hour ambulatory ECG.

Design—Original study.

Animals—188 Boxers > 9 months old; 31 had a history of syncope, and 157 were healthy (no history of syncope).

Procedure—In-hospital ECG was performed on all Boxers for at least 2 minutes. Within 7 days after the in-hospital ECG was completed, 24-hour ambulatory ECG was performed.

Results—The specificity of in-hospital ECG was 100% for the detection of at least 50 VPC in a 24-hour period in dogs with syncope and 93% in healthy dogs. In-hospital ECG had poor sensitivity, although sensitivity increased as the number of VPC per 24 hours increased.

Conclusions and Clinical Relevance—Use of in-hospital ECG is highly specific for detection of at least 50 VPC during a 24-hour period. However, in-hospital ECG is insensitive, and a lack of VPC does not suggest that the dog does not have a substantial number of VPC during that same period. The use of in-hospital ECG appears to be inadequate for screening purposes and therapeutic evaluations in mature Boxers with ventricular arrhythmic disease. (J Am Vet Med Assoc 2001;218:222–224)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine survival times in dogs with severe subvalvular aortic stenosis (SAS) treated by means of balloon valvuloplasty or with atenolol, a β-adrenoceptor blocking drug.

Design—Prospective study.

Animals—38 dogs < 24 months old with severe SAS (peak systolic pressure gradient ≥ 80 mm Hg).

Procedure—10 dogs underwent balloon valvuloplasty and were reexamined 6 weeks later to determine the feasibility of the procedure. The remaining 28 dogs were randomly assigned to undergo balloon valvuloplasty (n = 15) or to be treated with atenolol long term (13) and were reexamined annually for 9 years or until the time of death.

Results—For the first 10 dogs, mean pressure gradient 6 weeks after balloon valvuloplasty (mean ± SD, 119 ± 32.6 mm Hg) was significantly decreased, compared with mean baseline pressure gradient (167 ± 40.1 mm Hg). Median survival time for dogs that underwent balloon valvuloplasty (55 months) was not significantly different from median survival time for dogs treated with atenolol (56 months).

Conclusions and Clinical Relevance—Results suggest that balloon valvuloplasty can result in a significant decrease in the peak systolic pressure gradient in dogs with severe SAS, at least for the short term. No clear benefit in survival times was seen for dogs that underwent balloon valvuloplasty versus dogs that were treated with atenolol. (J Am Vet Med Assoc 2005;227:420–424)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare plasma fatty acid concentrations and the relationships of fatty acids to arrhythmias in Boxers versus Doberman Pinschers.

Animals—38 Boxers and 13 Doberman Pinschers.

Procedures—Boxers and Doberman Pinschers evaluated via Holter recording and for which a blood sample was available were included. Echocardiograms were performed in 49 of 51 dogs. The number of ventricular premature complexes (VPCs)/24 h was counted and fatty acids analyzed. Plasma fatty acid concentrations and VPCs/24 h, as well as correlations between the 2 variables, were compared between the 2 breeds.

Results—Compared with the Doberman Pinschers, Boxers had significantly higher plasma concentrations of γ-linolenic acid but lower concentrations of arachidonic acid. Total n-6 fatty acids and total polyunsaturated fatty acid concentrations were higher in Doberman Pinschers. There were significant, but weak, positive correlations between VPCs and oleic acid, total n-3 fatty acids, and total n-9 fatty acids in Boxers but not in Doberman Pinschers.

Conclusions and Clinical Relevance—Data suggested that plasma fatty acid concentrations may differ between Boxers and Doberman Pinschers and that the relationship between fatty acid concentrations and VPCs may be different between these 2 breeds.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate a group of related Rhodesian Ridgebacks with a family history of sudden death for the presence of arrhythmia and to identify possible patterns of disease inheritance among these dogs.

DESIGN Prospective case series and pedigree investigation.

ANIMALS 25 Rhodesian Ridgebacks with shared bloodlines.

PROCEDURES Pedigrees of 4 young dogs (1 female and 3 males; age, 7 to 12 months) that died suddenly were evaluated, and owners of closely related dogs were asked to participate in the study. Dogs were evaluated by 24-hour Holter monitoring, standard ECG, echocardiography, or some combination of these to assess cardiac status. Necropsy reports, if available, were reviewed.

RESULTS 31 close relatives of the 4 deceased dogs were identified. Of 21 dogs available for examination, 8 (2 males and 6 females) had ventricular tachyarrhythmias (90 to 8,700 ventricular premature complexes [VPCs]/24 h). No dogs had clinical signs of cardiac disease reported. Echocardiographic or necropsy evaluation for 7 of 12 dogs deemed affected (ie, with frequent or complex VPCs or sudden death) did not identify structural lesions. Five of 6 screened parents of affected dogs had 0 to 5 VPCs/24 h (all singlets), consistent with a normal reading. Pedigree evaluation suggested an autosomal recessive pattern of inheritance, but autosomal dominant inheritance with incomplete penetrance could not be ruled out.

CONCLUSIONS AND CLINICAL RELEVANCE Holter monitoring of Rhodesian Ridgebacks with a family history of an arrhythmia or sudden death is recommended for early diagnosis of disease. An autosomal recessive pattern of inheritance in the studied dogs was likely, and inbreeding should be strongly discouraged.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether plasma concentrations of tumor necrosis factor-α (TNF-α) are increased in cats with congestive heart failure (CHF) secondary to cardiomyopathy.

Animals—26 adult cats with CHF and cardiomyopathy and 9 healthy control cats.

Procedure—Plasma concentrations of TNF-α were measured in cats with CHF and cardiomyopathy. Tumor necrosis factor-α was measured by quantifying cytotoxic effects of TNF-α on L929 murine fibrosarcoma cells.

Results—Concentrations of TNF-α were increased (0.13 to 3.6 U/ml) in 10 of 26 cats with CHF but were undetectable in the other 16 cats with CHF and all control cats. In 20 of 26 cats with CHF, right-sided heart failure (RHF) was evident; TNF-α concentrations were increased in 9 of these 20 cats. The remaining 6 cats had left-sided heart failure (LHF); TNF-α concentrations were increased in only 1 of these cats. Age of cats with LHF (mean ± SD, 12.1 ± 6.2 years) was not significantly different from age of the cohort with RHF (10.5 ± 5.2 years). Body weight of cats with increased TNFα concentrations (5.4 ± 1.8 kg) was not significantly different from body weight of cats with CHF that did not have measurable concentrations of TNF-α (4.7 ± 1.6 kg).

Conclusionss and Clinical Relevance—Concentrations of TNF-α were increased in many cats with CHF. Cats with RHF were most likely to have increased TNF-α concentrations. Increased plasma concentrations of TNF-α in cats with CHF may offer insights into the pathophysiologic mechanisms of heart failure and provide targets for therapeutic interventions. (Am J Vet Res 2002;63:640–642)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the coding region of the cardiac actin gene in Doberman Pinschers with dilated cardiomyopathy (DCM) for mutations that could be responsible for the development of the condition

Animals—28 dogs (16 Doberman Pinschers with DCM and 12 mixed-breed control dogs).

Procedure—Ten milliliters of blood was collected from each dog for DNA extraction. Polymerase chain reaction (PCR) primers were designed to amplify canine exonic regions, using the sequences of exons 2 to 6 of the cardiac actin gene. Single-stranded conformational polymorphism analysis was performed for each exon with all samples. Autoradiographs were analyzed for banding patterns specific to affected dogs. The DNA sequencing was performed on a selected group of affected and control dogs.

Results—Molecular analysis of exons 2 to 6 of the cardiac actin gene did not reveal any differences in base pairs between affected dogs and control dogs selected for DNA evaluation.

Conclusions—Mutations in exons 5 and 6 of the cardiac actin gene that have been reported in humans with familial DCM do not appear to be the cause of familial DCM in Doberman Pinschers. Additionally, evaluation of exons 2 to 6 for causative mutations did not reveal a cause for inherited DCM in these Doberman Pinschers. Although there is evidence that DCM in Doberman Pinschers is an inherited problem, a molecular basis for this condition remains unresolved. Evaluation of other genes coding for cytoskeletal proteins is warranted. ( Am J Vet Res 2001;62:33–36)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To perform polymerase chain reaction (PCR) analysis on paraffin-embedded myocardium from dogs with dilated cardiomyopathy (DCM) and dogs with myocarditis to screen for canine parvovirus, adenovirus types 1 and 2, and herpesvirus.

Sample Population—Myocardial specimens from 18 dogs with an antemortem diagnosis of DCM and 9 dogs with a histopathologic diagnosis of myocarditis were evaluated.

Procedure—Paraffin-embedded myocardial specimens were screened for viral genome by PCR analysis. Positive-control specimens were developed from cell cultures as well as paraffin-embedded tissue specimens from dogs with clinical and histopathologic diagnoses of viral infection with canine parvovirus, adenovirus types 1 and 2, and herpesvirus. The histologic characteristics of all myocardial specimens were classified regarding extent, location, and type of inflammation and fibrosis.

Results—Canine adenovirus type 1 was amplified from 1 specimen from a dog with DCM. Canine parvovirus, adenovirus type 2, and herpesvirus were not amplified from any myocardial specimens. Histologic analysis of specimens from dogs with DCM revealed variable amounts of fibrosis; myocardial inflammation was observed in 1 affected dog. Histopathologic analysis of specimens from dogs with myocarditis disclosed variable degrees of inflammation and fibrosis.

Conclusions and Clinical Relevance—Viral agents canine parvovirus, adenovirus types 1 and 2, and herpesvirus are not commonly associated with DCM or active myocarditis in dogs. Additional studies evaluating for nucleic acid from viruses that less commonly affect dogs or different types of infectious agents may be warranted to gain insight into the cause of DCM and myocarditis in dogs. ( Am J Vet Res 2001;62: 130–135)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the usefulness of echocardiography in the diagnosis of heartworm disease in cats and to compare this modality with other tests.

Design—Retrospective study.

Animals—43 cats with heartworm infection that had echocardiographic examinations at 2 veterinary teaching hospitals between 1985 and 1997. Twenty-two of these 43 cats also underwent radiography of the thorax and heartworm antibody and heartworm antigen testing.

Procedure—Cats were determined to be infected with Dirofilaria immitis infection on the basis of 1 or more of the following findings: positive modified Knott or antigen test result, echocardiographic evidence of heartworm disease, or confirmation of the disease on postmortem examination. The percentage of echocardiographs in which heartworms were evident was compared with the percentage of radiographs in which pulmonary artery enlargement was evident and results of antigen or antibody tests in cats in which all tests were performed.

Results—Overall, heartworms were detectable by use of echocardiography in 17 of 43 cats, most often in the pulmonary arteries. In the 22 cats in which all tests were performed, antibody test results were positive in 18, antigen test results were positive in 12, and pulmonary artery enlargement was evident radiographically and heartworms were identifiable echocardiographically in 14. Heartworm infection was diagnosed exclusively by use of echocardiography in 5 cats in which the antigen test result was negative.

Conclusions and Clinical Relevance—Although echocardiography was less sensitive than antigen testing, it was a useful adjunctive test in cats that had negative antigen test results in which there was a suspicion of heartworm disease. The pulmonary arteries should be evaluated carefully to increase the likelihood of detection of heartworms echocardiographically. ( J Am Vet Med Assoc2001;218:66–69)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine electrocardiographic parameters in healthy llamas and alpacas.

Animals—23 llamas and 12 alpacas.

Procedure—Electrocardiography was performed in nonsedated standing llamas and alpacas by use of multiple simultaneous lead recording (bipolar limb, unipolar augmented limb, and unipolar precordial leads).

Results—Common features of ECGs of llamas and alpacas included low voltage of QRS complexes, variable morphology of QRS complexes among camelids, and mean depolarization vectors (mean electrical axes) that were directed dorsocranially and to the right. Durations of the QT interval and ST segment were negatively correlated with heart rate.

Conclusions and Clinical Relevance—ECGs of acceptable quality can be consistently recorded in nonsedated standing llamas and alpacas. Features of ECGs in llamas and alpacas are similar to those of other ruminants. Changes in the morphology of the QRS complexes and mean electrical axis are unlikely to be sensitive indicators of ventricular enlargement in llamas and alpacas. (Am J Vet Res 2004;65:1719–1723)

Full access
in American Journal of Veterinary Research