Cardiology monitoring for early detection of inheritable heart diseases

Clinical Need

In recent years, more and more attention is raised for breed specific inheritable diseases. Good examples are Mitral Valve Disease in the Cavalier King Charles Spaniel, and Hypertrophic Cardiomyopathy in Ragdoll and Maine Coon Cats.

Feline Hypertrophic Cardiomyopathy

Feline Hypertrophic Cardiomyopathy is the most common form of heart disease in cats. There is evidence that some forms of HCM are hereditary. However, cats can also develop HCM without a genetic predisposition, or develop HCM secondary from other diseases like hyperthyroidism or systemic hypertension (1).

Specific genetic mutations have been identified in both Maine Coon and Ragdoll cats. The presence of such a mutation increases the risk of developing HCM. However, the correlation between the genetic mutations and the development of HCM is not 1:1. Not all cats with the genetic mutations develop HCM, and not all Ragdoll or Maine Coon cats that do develop HCM possess the mutation. (2) So, it is likely that other, not yet identified genetic factors play a role in the development of the disease, next to environmental factors.

Cats with HCM show a hypertrophied, non dilated left ventricle, in absence of an obvious cause for this. HCM leads to a diastolic dysfunction and eventually to congestive heart failure. (1) This may lead to difficulties to breath, and fainting. Thrombi-embolism is a common complication (3).

Mitral Valve Disease

Valvular endocardiosis is an important cardiac disease, especially in small dogs and toy breeds. It is the most common form cause of congestive heart failure in old dogs. The Cavalier King Charles Spaniel has a ‘unique’ predisposition for this disease: at the age of 4 years old the prevalence among this breed is almost 50%. At an age of 10, the prevalence is 100%. (4). The heritability of cardiac murmur in Cavaliers has been estimated to be 0.64 (0.07) . Mitral Valve Disease is probably a polygenetic trait (7), but not all the involving genes have been identified yet. There is no genetic test for the disease (7).

Cavalier King Charles Spaniel Clubs in several countries have made ‘Mitral Valve Disease Breeding Protocols’ in an attempt to lower the prevalence of MVD among this breed. Though the protocols differ between countries, they use a combination of auscultation and/or echocardiography in order to detect early onset MVD: MVD occurring before the age of 5. The MVD breeding protocols are based on the following assumption: The disease can be decreased and the age of onset delayed by following guidelines of only breeding cavaliers who are over the age of 2.5 years, have hearts free from MVD murmurs, and have parents whose hearts were MVD murmur-free at age 5 years. No cavaliers should be bred which have murmurs before age 5 years. (5) (6)

So, by thorough screening of the heart of young Cavalier King Charles Spaniels by echocardiography and auscultation before breeding, the prevalence of the disease in the population can be reduced. Esaote developed a range of technologies that enable the sonographer to obtain high quality images for accurate diagnosis of cardiac pathologies. In this way we contribute to prevention of heritable diseases in future generations of animals.

Because both Mitral Valve Disease and Hypertrophic Cardiomyopathy have a hereditable background, it is important for breeders to know which animals are affected. These animals can be registered and kept out of the breeding population. For both MVD and HCM, ultrasound is an important part of the screening process.

Clinical Solution

To start with, Esaote offers both high frequency and low frequency phased array probes. In this way, the sonographer is able to obtain high quality images from both small rag doll cats to your biggest German Shepherd. Connecting your system to ECG offers you the possibility to determine the precise moment of diastole and systole in an easy way. Continuous Doppler and Pulsed Wave Doppler enable the detection of high velocity flow. Esaotes Colour Doppler CFM is highly adjustable, visualizing both high and low flow velocities.

Advanced cardiology

Compass M Mode (CMM): an orientable processing line enabling you to obtain a quality M-Mode image even if your patients condition is too bad to be in a position ideal for echocardiography.

Tissue Velocity Mapping: enables you to assess the movement of the heart muscle visualized by different colours.

Bibliography

1. Linquist, Eric, et al. The Curbside Guide: Diagnosis & Treatment of Common Sonographically Detected Disease, Canine & Feline. United States of America : SonoPath LCC, 2015.
2. International Cat Care. Hypertrophic cardiomyopathy (HCM) and Testing. icatcare.org . [Online] icatcare.org/advice/cat-health/hypertrophic-cardiomyopathy-hcm-and-testing.
3. Faculty of Veterinary Medicine, Utrecht University. Syllabus Circulation . Utrecht : sn, 2010-2011.
4. Mc Gavin, M. Donald en Zachary, James F. Pathologic Basis of Veterinary Disease, 4th edition. St. Louis, Missouri : Mosby Elsevier, 2007.
5. UFAW. Genetic Welfare Problems of Companion Animals. [Online] [Citaat van: 8 12 2016.] www.ufaw.org.uk/dogs/cavalier-king-charles-spaniel-mitral-valve-disease.
6. Beardow, Andrew, et al. INTERNATIONAL SYMPOSIUM ON CHRONIC CARDIAC VALVE DISEASE (CVD) IN THE CAVALIER KING CHARLES SPANIEL. sl : Cavalier King Charles Spaniel Club, USA, 1998.
7. Cavalier Health, [Online] [Citaat van: 12 8 2016.] cavalierhealth.org/mvdprotocol.htm.

Technology and features are system/configuration dependent. Specifications subject to change without notice. Information might refer to products or modalities not yet approved in all countries. Product images are for illustrative purposes only. For further details, please contact your Esaote sales representative.

Prevention