Inheritance of ventricular arrhythmias in Rhodesian ridgebacks
Kathryn Meurs and others, North Carolina State University, Raleigh
Ventricular arrhythmias have been reported as causing sudden deaths in young German shepherd dogs and English springer spaniels. The authors suspected a similar abnormality in four related young Rhodesian ridgebacks that died between seven and 12 months of age.
The owners of 21 relatives agreed to allow their dogs to undergo procedures including 24-hour Holter monitoring, standard ECG and echocardiography. In this group, two male and six female dogs had ventricular tachyarrhythmias. None of the 21 dogs had clinical signs of cardiac disease and neither echocardiography procedures or necropsy examinations of those dogs that died showed evidence of structural abnormalities.
While an autosomal dominant inheritance with incomplete penetrance could not be ruled out, pedigree examination suggested an autosomal recessive pattern of inheritance and inbreeding within the affected line should be strongly discouraged.
Journal of the American Veterinary Medical Association 248 (10): 1,135-1,138
Survival in cats with primary and secondary cardiomyopathies
Ilaria Spalla and others University of Milan, Italy
Feline cardiomyopathies are a heterogeneous group of diseases that can primarily affect the heart or be part of a generalised systemic illness. The authors examined a total of 94 cats including 50 with hypertrophic cardiomyopathy (HCM), 14 with restrictive cardiomyopathy (RCM) and 30 with secondary disease.
There was a significantly longer median survival time in cats with HCM rather than RCM, while less than 50% of those with a secondary condition died as a result of cardiac disease. Regardless of the disease type, significant risk factors included overt clinical signs, increased left atrial to aortic root ratio and a hypercoagulable state.
Journal of Feline Medicine and Surgery 18 (6): 501-509.
Analysis of cardiac dimensions during canine foetal echocardiography
Amalia Turner Giannico and others, Federal University of Parana, Brazil
Correlations between the dimensions of cardiac and non-cardiac structures are used in human medicine to identify pathological changes in the foetal heart but there is little published data on similar correlations in canine foetuses.
The authors carried out ultrasound examinations on 20 healthy pregnant bitches every four days through their pregnancy, recording 10 different cardiac parameters. Their findings confirm that quantitative evaluation of foetal cardiac structures can be used to monitor normal and abnormal cardiac development.
Veterinary Research Communications 40 (1): 11-20.
Dogs with persistent atrial standstill treated by pacemaker implantation
Justine Thomason and others Kansas State University, Manhattan
Persistent atrial standstill is a condition in dogs and humans that appears to be associated with Emery-Dreifuss muscular dystrophy. It is characterised by lymphocytic inflammation, fibrosis, fibro-elastosis and steatosis distributed variably among one or both atria and various other cardiac structures, causing signs of bradycardia and congestive heart failure.
The authors report four cases in client-owned dogs that were treated with pacemaker implants. Three were alive after 14 to 39 months and one was euthanised after 10.5 years.
Canadian Veterinary Journal 57 (3): 297- 298.
Evaluation of coagulation and brinolysis in horses with atrial fibrillation
Cristobel Navas de Solis and others, University of Pennsylvania
Atrial fibrillation is the most common clinically relevant, performance-limiting arrhythymia in horses. In human patients, atrial fibrillation is associated with a hypercoagulable state that creates a significant risk of a thrombo-embolism or stroke.
The authors examined 25 horses with atrial fibrillation for evidence of hypercoagulability. Compared with healthy controls, this group had significantly lower antithrombin activity but there were no significant differences in plasma brinogen and D-dimer concentrations.
Journal of the American Veterinary Medical Association 248 (2): 201-206.
Changes in cardiac parameters during recovery from an endurance ride
Mette Flethøj and others, University of Copenhagen
Endurance races place significant demands on an equine athlete and many studies have measured physiological parameters such as heart rate to ensure an animal’s welfare is not compromised and it is fit to continue. However, very little attention has been paid to cardiac and other values during the recovery phase.
The authors investigate physiological changes in 28 Arab horses competing in 120km or 160km rides. During recovery the heart rate was increased over pre-exercise levels and the standard deviation of normal R-R intervals decreased. Changes were also noted in biochemical parameters such as serum cardiac troponin and creatine kinase isoenzyme MB.
Journal of the American Veterinary Medical Association 248 (9): 1,034-1,042.
Effects of cardiovascular drugs on left atrial indices in healthy dogs
Tatsuyuki Osuga and others, Hokkaido University, Sapporo, Japan
The left atrium plays an important role in modulating left ventricular filling and there is a correlation between left atrial dysfunction and the severity of cardiac disease.
The authors used a novel technique known as 2-D speckle tracking echocardiography to assess the effects of different cardiac drugs on left atrial function. Their results show that after administration of dobutamine, esmolol, milrinone or phenylephrine to healthy dogs, left atrial phasic function indices were fairly stable and did not parallel changes in left ventricular function indices.
American Journal of Veterinary Research 76 (8): 702-709.
Acquired tricuspid valve stenosis associated with pacemaker implants
Emily Tomkins and others, Mid-Atlantic Equine Medical Center, Ringoes, New Jersey
Acquired tricuspid valve stenosis is a rare complication of endocardial pacing lead implantation in humans. It has been described only once previously in the veterinary literature in a dog with excessive lead redundancy. The authors describe another case in a 12-year-old female terrier.
The dog developed right-sided congestive heart failure six months post-implantation of a second ventricular endocardial pacing lead. The first began malfunctioning after 11 years. Medical management was unsuccessful and the patient was euthanised.
Journal of the American Animal Hospital Association 51 (3): 167-170.
Aberrant heartworm migration to the abdominal aorta in a dog
Janet Grimes and others, Texas A&M University, College Station
Infestation with the canine heartworm Diro laria immitis is a common presentation in the US, causing cough, dyspnoea, ascites and exercise intolerance. Cases of aberrant worm migration to other tissues have been recorded, resulting in conditions such as anterior uveitis.
The authors describe a case in which the larvae migrated to the abdominal aorta, causing systemic arteriolitis. The patient was a two-year-old dachshund with initial signs of vomiting and haemorrhagic diarrhoea. Abdominal ultrasound revealed worms in the abdominal aorta and an avascular segment of small intestine.
Canadian Veterinary Journal 57 (1): 76-80.
Pacemaker lead perforation of the right ventricle in a dog
Amanda Viavarella and others, Advanced Vetcare, Kensington, Victoria
Pacemaker perforation of the myocardium is a rare event in veterinary medicine and the risk factors have not been clearly defined.
The authors describe one such case in which cultures of blood from the pacemaker lead tip and surrounding tissues revealed a pure growth of the Gram-negative coccobacillus Moraxella phenylpyruvica. The patient was a 13-year-old neutered male Border collie, which presented with acute onset syncope, weakness and anorexia 10 months after the pacemaker implant. Post mortem examination revealed that the pacemaker lead had perforated the apex of the right ventricle.
Australian Veterinary Journal 94 (4): 101-106.
Arrhythmogenic right ventricular cardiomyopathy in a weimeraner
Bryan Eason and others, University of Missouri, Columbia
A 41kg four-year-old neutered male weimeraner was referred for evaluation of syncope, first noticed about two months earlier. A 24-hour ambulatory ECG revealed multiform ventricular ectopy with periods of ventricular tachycardia.
The patient received oral antiarrhythmia therapy with sotalol but despite a marked decrease in the frequency and complexity of its ventricular ectopy, the patient died suddenly three months later. Post mortem examination confirmed a diagnosis of arrhythmogenic right ventricular cardiomyopathy with fatty tissue infiltration of the right ventricular myocardium.
Canadian Veterinary Journal 56 (10): 1,035-1,042.
Diaphragmatic utter secondary to hypoparathyroidism in a dog
Daniela Vrabelova and others, Ohio State University, Columbus
Synchronous diaphragmatic utter or “thumps” is a rare condition characterised by hiccup-like contractions of the diaphragm leading to repetitive, involuntary abdominal wall contractions synchronous with the heartbeat. The authors describe such a case in a three-year-old spayed female miniature schnauzer.
The rates of contractions of the abdominal wall coincided with the heart rate and increased on exercise. Low plasma ionised calcium and serum parathyroid hormone concentrations indicated primary hypoparathyroidism. Treatment for the hypocalcaemia led to resolution of the diaphragmatic utter.
Journal of the American Animal Hospital Association 51 (6): 392-395.
