A Molecular test for Canine Dilated Cardiomyopathy
Canine Dilated Cardiomyopathy is due to the enlargement of the heart muscles and ultimately leads to heart failure.
Recent research at the Veterinary faculties of the University of Cambridge and Royal Veterinary Collage has confirmed that this disease found mainly in Dobermans, Irish wolfhounds and Great Danes has a very poor prognosis. This is mainly due to the fact that affected dogs may die suddenly or require long term therapy for heart failure.
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Dilated Cardiomyopathy in Great Danes is presumed to be an inherited disease and , because of a strong bias towards males being affected, recent USA research has suggested that this condition is X-chromosome linked. At present there is no screening test to prove which dogs would develop this condition. Diagnosis usually follows the onset of clinical signs of heart failure or the identification of an arrhythmia during a routine health check. The main clinical project is being conducted at Cambridge veterinary school and its aim is to investigate the inheritance of this condition in Great Danes by searching medical records and trying to establish pedigree links. Pedigree information is being requested for all dogs presented over the last five years. In addition to pedigree analysis, blood and muscle samples are being tested to trace the genetic link. This research has been copied from the parallels between man and this condition in dogs. Although not all inherited forms of this condition in man have been characterised fully in terms of their causative mutation, this ever growing field of research and the identification of new genes is gaining great strides in the field of research.
Genes currently under investigation include those coding for the X-linked proteins dystophin and emerin.
Investigation into these genes is being carried out on canine complementary DNA that has been extracted from normal and abnormal heart muscle. Heart muscle that has been collected from any dog that had previously been diagnosed with dilated cardiomyopathy and that has died or been euthanased due to clinical signs. Normal heart muscle was obtained from animals that had been euthanased or died from non-cardiac causes.
These specific cardiac genes are then selected and amplified at the DNA level before research can be carried out. The research is aimed at detected differences between normal and abnormal DNA sequences and then deducing and differentiating between disease causing and non-disease causing differences.
Examination of the consequences of such a sequence change will be used to determine whether this change is due to a true mutation of the genes resulting in the possibility of the disease developing in the dog.
The ultimate aim of this project would be to design a molecular genetic test that would be able to be used routinely in most veterinary clinics. These tests would then be performed on dogs showing no symptoms in order to identify whether they are carrying these genes and would show the disease later on in life. This work would then help control the spread of the disease in the population of Great Danes, preventing those dogs carrying the genes from breeding and passing on the problem.
Guy Liebenberg BSc BVSc MRCVS Cert Vet Acu
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