The following article published by the AKC is the newest article on Heart Health and is essential for many purposes. Many companion owners need to be aware of the warnings and advice of a breed's Parent Club; in this case, it would be the Irish Wolfhound Club of America (IWCA.)
Unfortunately, the IWCA is noticeably absent from this article in providing valuable and critical guidance to Wolfhound owners, as cardiac disease is one of the leading causes of death in Wolfhounds. In my opinion, based on the number of emails and requests I receive, it is the leading cause of death as, sadly, countless breeders do not educate their IW owners about Atrial Fibrillation and Dilated Cardiomyopathy (DCM), as well, Ventricular Premature Complexes (VPC). Many wolfhounds die needless early deaths because they were not properly and annually tested.
My policy has always been to inform Wolfhound owners that heart testing is imperative and mandatory beginning at age two and annually after that. Any advanced cardiac testing MUST include Auscultation, EKG and Echocardiograms.
The IWCA website states: It is important to remember that testing is important for all Irish Wolfhounds, not just those who are used for breeding. Early detection of changes in health often leads to a better quality of life for your dog. All Irish Wolfhounds may benefit when your dog participates in a health study that increases our knowledge…Cardiac screening in IWs should always be performed by a Board-certified veterinary cardiologist.
Canine Heart Health and Genetic Testing
By Claire Wiley, VMD, DACVIM
Published: Feb 22, 2024
Canine genetic tests are important and must be interpreted together. Phenotype refers to a dog’s observable traits, whereas genotype refers to a dog’s genetic constitution. Phenotypic tests are typically performed by a veterinarian or board-certified cardiologist. DNA tests can be used to determine a dog’s genotype for specific genetic variants, but phenotype tests are required to obtain a diagnosis of heart disease.
The heart is a complex organ that can manifest disease in multiple ways. Some heart diseases are present at birth (congenital), whereas others develop as the dog ages. These conditions can lead to symptoms such as coughing, lethargy, exercise intolerance, fainting, and even sudden death if left untreated. Some common heart diseases seen in dogs include:
1. Degenerative Mitral Valve Disease (DMVD)
This middle to old age disease is the most common of all canine heart diseases. One of the heart valves, the mitral valve, becomes thickened and damaged as the dog ages. The valve can leak blood and cause heart enlargement that can progress to congestive heart failure (CHF). Although small breed dogs are more prone to developing this disease, any dog can be affected. At the time of writing this article, no genetic tests are available to help predict the occurrence of this disease.
2. Dilated Cardiomyopathy (DCM)
With DCM, the second most common form of heart disease in dogs, the heart chambers become enlarged (dilated) and the walls become thin. DCM can have multiple causes, including inherited and nutritional. Multiple genetic variants have been identified that are associated with DCM that are typically breed-specific tests. Although some of these variants are inherited in a simple Mendelian fashion, others are complex and represent risk factors. Age of onset can vary from breed to breed. For example, Portuguese Water Dogs can develop an inherited, juvenile form that typically manifests before 6 months of age, called Juvenile Dilated Cardiomyopathy.
Phenotypic tests are crucial for evaluating the current function of the heart. Some common tests include:
1. Auscultation: Auscultation involves listening to the heart sounds using a stethoscope. Abnormalities such as murmurs, irregular rhythms, or gallops can indicate underlying cardiac issues.
2. Echocardiography: Echocardiography, or cardiac ultrasound, provides detailed images of the heart’s structure and function. It helps assess chamber sizes, valve function, and overall cardiac performance.
3. Electrocardiography (ECG or EKG): ECG records the electrical activity of the heart, helping identify arrhythmias and conduction abnormalities.
4. Chest radiographs: Radiographs offer valuable insights into the size and shape of the heart, as well as detecting signs of congestive heart failure, such as pulmonary edema or pleural effusion.
5. Holter Monitoring: Holter monitoring involves continuous ECG recording over 24-48 hours, allowing for the detection of intermittent arrhythmias.
The American Boxer Club, Inc., for example, recommends routine Holter monitoring annually for breeding to help decrease the incidence of Boxer Cardiomyopathy.
Genetic testing related to canine cardiac health is most important for informing breeding practices when selecting breeding pairs. The AKC DNA Program is about to launch genetic testing in the coming months, and several genetic variants for heart health are included in this panel.
Parent Club Recommended DNA Cardiac Health Tests:
Dilated Cardiomyopathy (Schnauzer Type) This specific genetic variant investigates a deletion in the RBM20 gene.
Juvenile Dilated Cardiomyopathy in Portuguese Water Dogs (Available only through PennGen) This genetic variant investigates a locus on canine chromosome 8.
Other AKC DNA + Health Heart Tests:
Cardiomyopathy and Juvenile Mortality. This genetic variant is associated with severe heart disease that can cause death from heart failure by 8 weeks of age.
Dilated Cardiomyopathy (Doberman Pinscher Type Risk Factor, Variant 1)
This specific genetic variant investigates a deletion in the PDK4 gene and is associated with disease in Doberman Pinschers, and its association with DCM in other breeds is not clear. This genetic variant is inherited in an autosomal dominant manner with incomplete penetrance. In other words, not every dog with this genetic variant goes on to develop the disease DCM.
Dilated Cardiomyopathy (Doberman Pinscher Type Risk Factor, Variant 2)
This specific genetic variant investigates a single nucleotide polymorphism (SNP) in the TTN gene and is associated with disease in Doberman Pinschers.
Canine genetic testing for heart disease represents a valuable tool in the arsenal against decreasing the risk of producing cardiac conditions in dogs. By leveraging the power of genetics, veterinarians and dog owners can work together to identify at-risk individuals, implement preventive measures, and provide personalized care to improve the overall cardiac health and well-being of our beloved canine companions. Each known genetic variant for DCM will be discussed in more detail in the coming months. As research continues to advance, genetic testing holds the promise of further enhancing our understanding and management of canine heart disease.
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