Dogs used as a model for heart research

Large-hearted Newfoundland dogs are being used to discover more about human heart disease. Dilated cardiomyopathy (DCM) is a heart ailment discovered in middle to old age in humans and in Newfoundland dogs aged four to eight years.

In dogs it results in heart failure and death. In humans the diseased heart chambers (myocardium) are usually treated by heart transplant. The insidious progression from normal to abnormal occurs over years and is consistent with a single gene disorder. Only one parent with one copy of the gene can transmit the disease to up to half the offspring in a litter.

Edinburgh University's Dr Joanna Dukes-McEwan is using Newfoundland dogs as a model for studying familial DCM in humans. She believes that the search for a genetic marker linked to the disease will be easier to find in the Newfoundlands than tracking it down through three generations of humans.

Dr Dukes-McEwan said: "We know that DCM is a genetically transmitted disease in Newfoundlands and shows the same pattern of inheritance as in humans. Studying the genetic basis of the dog disease will help elucidate the cause of some human cases."

''Because of the fast generation times in the dogs (usually about two years) we have access to three or more generations and there are a larger number of siblings in a litter. Most breeding dogs or bitches have multiple mates. We have shown from a prospective longitudinal study of the Newfoundlands that DCM is transmitted through each generation most consistent as an autosomal dominant trait, despite the inbred nature of dog pedigrees.''

Eventually, the genes will be investigated in normal and affected dogs to identify any differences resulting in abnormality in the encoded protein structure. This may be responsible for myocardial disruption.

The compromised function of the cytoskeleton (the internal scaffolding of the heart muscle cell) leads to its wear and tear and eventual inability to withstand the repeated contractions required of the cell.

If the mutation in the gene responsible for causing DCM in Newfoundland dogs is identified and found to be mirrored in humans, it will lead to potential treatments or gene therapy.

University of Edinburgh website