Genetics

Many of the common cardiac diseases of dogs and cats have a familial basis. Every effort should to be made to exclude affected animals from the breeding gene pool if the incidence of these conditions is to be reduced and this is the main aim of heart testing. Other secondary aims include providing information on the incidence and patterns of inheritance of these diseases and collecting genetic material that can be used to investigate their genetic basis.

The best test for a genetic disease is one that identifies the specific genetic mutation responsible for causing the disease - a so called "gene test". Efforts to identify these mutations have however so far proved inconclusive in the majority of cases. 

Hypertrophic Cardiomyopathy (HCM) in the Maine Coon and Ragdoll cat breeds, arrhythmogenic right ventricular cardiomyopathy (ARVC) in Boxer dogs and dilated cardiomyopathy (DCM) in Doberman Pinschers are the noticeable exceptions. 

In HCM in Maine Coons and Ragdolls mutation on the gene that codes for an important structural protein of the myocardium (myosin binding protein C) has been identified in affected cats of these breeds and genetic tests are available commercially to screen for this mutation. False positives and false negatives occur however with some "gene test negative" cats developing the disease whilst some "gene test positive" cats don't.

Genetic testing has also recently become available for ARCV in Boxers and DCM in Doberman Pinschers. 

More information on genetic tesing is available at the veterinary cardiac genetics laboratory at North Carolina State Universtiy:

http://www.cvm.ncsu.edu/vhc/csds/vcgl/

and from ASAP laboratories:

http://asaplab.com.au/dnatesting/index.html

 We lack a gene test for most of the familial cardiac diseases that affect our patients and screening for these conditions therefore relies on identifying the result of these mutations - the so called phenotype. Cardiac auscultation is a good initial screening test as it is relatively quick and well tolerated, and many of the affected animals will have an audible cardiac abnormality (heart murmur, cardiac gallop sound, and arrhythmia). Doppler echocardiography provides more conclusive evidence for or against the presence of cardiac disease by allowing direct visualisation of the various structures of the heart.

© CardioRespiratory Pet Referrals Victoria 2012