What’s new in cardiothoracics? - Veterinary Practice
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What’s new in cardiothoracics?

Our monthly summary of the latest academic publications on this month’s spotlight topics of cardiology and thoracic medicine

Effective treatment of feline hypertrophic cardiomyopathy with rapamycin

Joanna Kaplan and others, University of California, Davis

Hypertrophic cardiomyopathy is the most common cardiovascular disease in domestic cats. While some patients remain subclinical throughout their lives, many cases develop into irreversible left-sided congestive heart failure, arterial thromboembolism or sudden death. Rapamycin is an immunosuppressant that has been shown to reverse cardiac hypertrophy in human patients and rodent disease models. The authors investigated the effects of once-weekly doses of high- and low-dose rapamycin for six months in 43 client-owned cats with subclinical hypertrophic cardiomyopathy. There was no evidence of any adverse effects, and the primary clinical finding was a reduction in left ventricular myocardial wall thickness. This suggests that treatment may prevent or delay progressive left ventricular hypertrophy in cats.

Journal of the American Veterinary Medical Association, 261, 1-10

Serum magnesium concentrations in dogs with myxomatous mitral valve disease

Ock-Kyu Kim and others, Chonnam National University, Gwangiu, South Korea

Hypomagnesaemia is associated with a poor prognosis in human patients with congestive heart failure, but evidence for an equivalent association in veterinary patients is limited. The authors measured serum ionised magnesium levels in 181 client-owned dogs at different stages in the development of myxomatous mitral valve disease (MMVD). Their findings indicate that serum magnesium levels are indeed lower in dogs with more advanced mitral valve disease. They suggest that measurements of magnesium ion concentrations could serve as a potential marker for estimating the severity of the disease and an indirect indicator of the prognosis of dogs with MMVD.

Journal of Veterinary Internal Medicine, 38, 41-50

Frequency of arrhythmias in 9,440 cats by breed, age and sex

Donald Szlosek and others, IDEXX Laboratories, Westbrook, Maine

Heart disease is one of the leading causes of mortality in domestic cats, and breed-specific mutations have been linked to the emergence of cardiac disease in some breeds. The authors conducted a large-scale survey of the frequency of arrhythmias in specific breeds, together with the influence of age and sex. In a total of 9,440 cats given an electrocardiogram, they found 249 cases in which at least one arrhythmia was present. These abnormalities were more common in older cats, males and members of the Ragdoll breed. Although the presence of an arrhythmia does not always indicate the presence of a clinically relevant condition, these findings may help in the design of more effective screening programmes for cardiac disease in cats.

Journal of Veterinary Cardiology, 51, 116-123

Lung lobe torsion associated with chest wall defects in a dog

Meeso Huh and Sungin Lee, Chungbuk National University, Cheongiu, South Korea

Lung lobe torsion is a rare finding in dogs. While the underlying cause is frequently unknown, any condition that increases lung lobe mobility may raise the risk of torsion. The authors describe a case associated with a congenital chest wall defect in an eight-year-old neutered female Poodle. The patient presented with signs including exercise intolerance, lethargy and respiratory distress. Computed tomography revealed abnormalities in the fifth and sixth ribs and torsion affecting the left cranial lung lobe. After removing the affected lobe and repairing the chest wall defect, the respiratory signs improved, and no significant complications were identified during a two-year follow-up period.

Journal of Small Animal Practice, 65, 1-84

Metabolites associated with cachexia in dogs with myxomatous mitral valve disease

Lisa Freeman and others, Tufts University, North Grafton, Massachusetts

Congestive heart failure may occur towards the end of many different disease processes. Cardiac muscle wastage is present in many cases and appears to be an independent indicator of morbidity and mortality. The authors investigated the metabolomic profile of dogs with MMVD with and without signs of cachexia. A combined mass spectrometry/high performance liquid chromatography analysis of samples from dogs in both groups showed significant differences in the level of hundreds of different metabolites, notably dicarboxylates and acylcarnitines. They suggest that better knowledge of the nature and significance of these differences may allow earlier identification and treatment of dogs with cardiac cachexia.

American Journal of Veterinary Research, 11, 84

Pulmonary lobectomy for the treatment of acinar adenocarcinoma in a rabbit

Laura Mercardo and others, FauneVET, Nantes, France

Lung adenocarcinomas and epitheliomas have been identified in retrospective post-mortem studies in rabbits, but primary lung neoplasms have rarely been reported in clinical cases in this species. The authors describe the diagnosis and successful surgical outcome of an eight-year-old pet rabbit with an acinar adenocarcinoma. The rabbit had a history of dyspnoea that appeared to be getting worse. Radiographic, computed tomography and ultrasound examinations identified a lesion in the right medial pulmonary lobe. Fine needle aspiration indicated an epithelial neoplasm and histological analysis suggested an acinar adenocarcinoma. Following surgery to remove the affected lobe, the patient recovered uneventfully, with an improved appetite and faecal output.

Journal of Exotic Pet Medicine, 47, 9-13

An idiopathic synchronous diaphragmatic flutter in a Jack Russell Terrier

Gregoire Bernardo Marques and others, University of Lyon, France

Synchronous diaphragmatic flutter is a rare condition in which contractions of the diaphragm result in involuntary abdominal wall contractions synchronous with the heartbeat. It is thought to be caused by electrical activity in the heart muscle causing aberrant depolarisation of the nearby phrenic nerve. The condition may be associated with hypocalcaemia, but sometimes there is no obvious cause. The authors describe one such case in a two-year-old neutered male Jack Russell. The involuntary contractions had been apparent for about 18 months. Electrocardiography and fluoroscopy examinations showed that the movements were synchronous with the heartbeat, but thoracic radiographs, echocardiography and serum electrolytes did not reveal an underlying cause.

Canadian Veterinary Journal, 64, 930-932

Diagnostic validation of a vertebral heart score machine learning algorithm

Jessica Solomon and others, IDEXX Laboratories, Westbrook, Maine

The vertebral heart score (VHS) is a method used to measure heart size in relation to the appearance of the thoracic vertebrae in lateral radiographs. The VHS is considered a useful tool for identifying and staging heart disease, as well as a source of prognostic information. The authors compared the results of a VHS algorithm with the opinions of three board-certified cardiologists in examinations of 1,200 canine lateral radiographs. Although their findings suggest that the performance of the algorithm when measuring heart size in dogs was comparable to that of the three experienced veterinary cardiologists, they state that further assessment would be needed before recommending this technology for use in a clinical setting.

Journal of Small Animal Practice, 64, 769-775

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