Most of our genetics work is done here in the laboratory at the College of Veterinary Medicine looking at DNA samples from dogs and cats with heart disease. However, occasionally we like to get out in the "field" and visit with pet owners and their dogs and cats. This Saturday I had the pleasure of working with several Pomeranian owners in the Tacoma area. We are interested in an inherited heart defect called Pulmonic Stenosis. This is a defect where the base of the pulmonary artery is too narrow. Affected dogs may progress into heart failure and some die suddenly. Our laboratory is interested in collecting DNA samples from dogs affected with this defect. I examined 67 Pomeranians on Saturday and I am very pleased to say that they were ALL EXTREMELY HEALTHY (as well as extremely charming and cute) !!! None of them had the defect. It was a great opportunity for me to examine so many dogs in one place and I greatly appreciate the efforts of the owners and dogs for participating. The dogs seemed to enjoy the day as well I think, although I'm pretty sure Coltin (see picture below) was ready for me to leave by the time i took this picture!!

Until there is a genetic marker available many people use annual Holter monitoring to screen for the ventricular premature beats (VPCs) that are indications of early Boxer Arrhythmogenic Right Ventricular Cardiomyopathy. There are many services available to read the Holter tapes and smartcards but not all services are alike. The prices for interpretation are quite variable. One of the least expensive forms of analysis is the technician run service-- with many technician read services (including ours) a technician starts the analysis, looks for common issues and problems that would make the analysis invalid and reads the tape under the guidance of the computer's scientific algorithm for what normal and abnormal beats are. This generally takes about 1-2 hours of technician time and the cost is between $20-40.00 depending on the company. However , it should be remembered that computer algorithms are not as accurate as a trained human. Computers frequently call simple movement of the wires by a dog scratching his back- a VPC, or many VPCs. Computers also sometimes ignore true abnormalities and call them normal. Therefore, a more accurate method (but also more time consuming and expensive) is to have a technician with direct supervision of a cardiologist analyze every single heart beat of the tape and determine if it is real or not.(See a picture of Jan working on a reading below!)  A dog has about 100,000 heart beats/day so this takes more time (sometimes up to 20 hours/tape, but usually 4-5 hours) and requires input by a cardiologist to oversee and make the final call on complicated beats. So, this method is more expensive!  Therefore, from a financial perspective- if someone was really on a tight budget, they might do a technician run service and if it clear (NO VPCs)- great. If it is abnormal it may be worth spending the extra money to have a cardiologist read it before making any decisions about treatment or breeding.    

The most common form of heart disease in the cat is a disease called hypertrophic cardiomyopathy. Cardimyopathy simply means heart muscle disease. The term "Hypertrophic" implies that the heart muscle is thickened. Human beings also suffer from this same disease and we know it is inherited in many humans and caused by a genetic mutation in one of 20 different genes. We have previously identified 2 different genetic mutations in the Maine Coon and Ragdoll breeds that result in the development of this disease in those breeds. The mutations in those breeds was identified in one of the most commonly mutated genes that result in the human disease.  Unfortunately, many other breeds of cats suffer from  this disease and do not have either of the previously identified mutations. As of today we have completed evaluation of the 8 most common genes that cause the human disease in several breeds of cats including the Maine Coon, British Shorthair, Norwegian Forest Cat, Siberian and Sphynx. Unfortunately we did not identify any mutations in any of the breeds in any of these important genes that cause the human disease!! However, we don't give up easiy and we have now recieved funding from the American Veterinary Internal Medicine Foundation to study the next 4 genes! We will be studying the Bengal cat as well. We'll keep you posted! 

Many of our research projects are genetic studies. In some cases, we are studying pedigrees of animals with heart disease to determine the mode of transmission of a trait (or how a trait is inherited). There are a few common "modes" including X-linked, Autosomal recessive and Autsomal dominant.

X-linked traits are those in which the disease or defect may be seen more in males than females and females can be silent carriers. There is some evidence that dilated cardiomyopathy (DCM) in the Great Dane is inherited this way (at least in some familes). Since females can be silent carriers and males tend to show the trait, it may first seem that the trait is passed from the father, but it actually came from the mother who was a silent carrier. 

 Other forms of cardiomyopathy in the dog including Boxer ARVC and Doberman pinscher Dialted Cardiomyopathy, as well as Hypertrophic cardiomyopathy in the cat are autosomal dominant traits. In these cases, males and females are generally equally affected and every affected individual should have at least one affected parent. The trait should show up in every generation.

Geneticists generally study the information from the animal's pedigree by putting it into a pedigree drawing in which each animal is represented as a circle or a square. Traditionally, affected animals are represented by black symbols and unaffected animals are represented by white symbols. Male animals are represented by squares and females by circles. The attached pedigree drawing is from a family of Doberman pinschrers with dilated cardiomyopathy. One can see 4 affected males (black squares) and 4 affected females (black circles).

Welcome to the first blog of the VCGL. We will be using this site to discuss current activities in the Veterinary Cardiac Genetics Laboratory. One of the projects that we have been working on  for several years now is the identification of a genetic marker for a disease in the Boxer dog called Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC). Many people know this disease by its previous name, Boxer cardiomyopathy.  ARVC is an important disease in the Boxer because it can lead to sudden cardiac death in an otherwise happy, healthy adult dog. We started this project by collecting DNA samples from hundreds of unaffected and affected Boxers and have been looking for the DNA differences between the two groups of dogs. One of our very important scientists, Mandy Kuan, has been assisting with this project. Mandy will be returning to her home in China for a few months but has left the project in great shape for continued progress in her absence.