HCM and FIP: definition, diagnosis, and treatment
HCM and your Sphynx
April 18, 2017
What Health issues should I be worried about with a Sphynx? Learn about HCM and be sure to have your sphynx checked at a well exam at least once a year for signs of HCM
Here is a great article by Dr. Becker that I want to share that helps explain HCM and gives you a better understanding of HCM. This article is going to discuss feline cardiomyopathy.
Cardiomyopathy is a big fancy word.
But you can break it down to "cardio" (meaning heart), "myo" (the Latin word for muscle), and "pathy," which means disease.
So what you have is a disease of the heart muscle
There are different kinds of cardiomyopathy, including hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, and unclassified cardiomyopathy.
Hypertrophic cardiomyopathy, or HCM, is the most common acquired heart disease in cats, and that's what will be discussed today.
Hypertrophic cardiomyopathy is common in cats, but rarely seen in dogs.
The word "hypertrophic" means thickened, so this is a condition where the walls and ventricles of the heart become much too thick, or hypertrophied. Several other diseases also cause thickening of the left ventricular wall, including aortic stenosis, hyperthyroidism, and systemic hypertension (high blood pressure). HCM is diagnosed once other causes have been ruled out.
HCM is often inherited in cats. In fact, there's a test available now for a specific gene mutation in Maine Coons and ragdolls. Purebred cats such as the Persian, other oriental breeds, and American shorthairs are also predisposed to develop the condition.
However, it's the regular house cat that is most commonly diagnosed with HCM. Cats usually develop the condition in midlife, but it can occur at any age.
How HCM Damages the Heart
When you work a muscle it gets bigger, and that's a good thing, right? It is – except in the case of the heart muscle.
The thickening that occurs with HCM and causes growth of the heart muscle isn't normal or desired. The severity of the condition depends on how thick the muscle wall ultimately gets. Some kitties develop only minor thickening; others develop a much more significant problem.
As HCM progresses, the actual structure of the heart changes and heart function is affected. Thickened muscle walls become less flexible, and the left ventricle can no longer relax or stretch efficiently to fill with blood.
These changes can create a heart murmur because the heart valves don't grow as the heart muscle enlarges. The valves become insufficient. This can also cause a buildup of blood in the left atrium of the heart, which forces fluid back into the lungs and into the chest cavity, which ultimately causes congestive heart failure.
In some cats, thankfully not many, the thickening of the heart causes an arrhythmia that can bring on sudden death. And some kitties develop feline aortic thromboembolism, also called FATE, which is a blood clot that forms in the aorta and blocks the flow of blood, usually to the back legs.
Needless to say, this causes sudden paralysis, a tremendous amount of pain for the cat, and even death.
Symptoms of feline hypertrophic cardiomyopathy vary and depend to some extent on the severity of the disease. Cats with mild disease don't necessarily have symptoms. But in a kitty with significant HCM, there are usually obvious signs.
As we know, kitties mask illnesses very well. So until this condition is severe, even a cat with significant disease may have no symptoms, or very mild symptoms that don't seem to be indicative of heart disease.
In cats with obvious symptoms, there can be respiratory distress caused by congestive heart failure, or leg paralysis due to a blood clot.
Cats suffering congestive heart failure don't cough like people or dogs do. Instead, they tend to breathe through an open mouth, and there can even be some panting. You should watch for breathing difficulties during exertion. Some kitties with HCM and congestive heart failure have a hard time walking any distance without stopping to rest and recuperate.
Diagnosis of HCM
: from UC DAVIS University
Hypertrophic cardiomyopathy (HCM) is the most common heart disease of cats, whether they are random bred or pedigreed. It is a heart muscle disease in which the papillary muscles (the muscles in the left ventricle that anchor the mitral valve) and the walls of the left ventricle become abnormally thickened. HCM is often a progressive disease, and a proportion of affected cats develop heart failure if the muscle hypertrophy and subsequent scarring of the heart muscle significantly affects heart function. Cats with the disease may die suddenly and may develop a blood clot in the chamber above the left ventricle (i.e., the left atrium) that often then gets carried into the systemic arterial system, most commonly lodging in the terminal aorta, stopping blood flow to the rear legs.
This is currently unknown in most cats although familial (hereditary) HCM has been observed in several breeds, such as the Maine Coon and American Shorthair. Anecdotal information suggests there is familial HCM in many other breeds. Heart muscle hypertrophy in cats can be caused by other diseases, such as systemic hypertension (high blood pressure) and hyperthyroidism. HCM is a primary disease of the heart muscle. Hypertension and hyperthyroidism cause secondary thickening of the left ventricle and so are not causes of HCM (although it is possible that they may exacerbate the disease if they become present in a cat with mild to moderate HCM). HCM is diagnosed when these other causes are ruled out.
In Maine Coons and American Shorthairs, HCM has been confirmed as an autosomal dominant inherited trait, as it is in humans where over 200 gene mutations in 10 genes have been found to cause the disease. The disease has variable expression; meaning some cats are severely affected, others are only mildly to moderately affected, and some cats may not have evidence of the disease yet produce affected offspring.
Recently, a mutation in the cardiac myosin binding protein C (cMyBP-C) gene causing HCM in the Maine Coon cat has been identified. Undoubtedly, other mutations responsible for HCM in cats remain to be discovered. However, since few veterinary cardiologists and geneticists have the expertise to study genes, it may be some time before the responsible gene or genes for each affected breed will be found. The mutation identified as a cause of HCM in Maine Coon cats may not be the same mutation or even on the same gene in other breeds. The genetics of HCM in each breed will require investigation of each individual breed.
In clinical practice, the most common patients tested for HCM with echocardiography are cats with suggestive clinical signs of heart disease, such as a heart murmur. Testing cats used in a pedigreed breeding program is a more difficult endeavor. Echocardiography is not a perfect tool for diagnosis of HCM – some affected individuals will escape detection and access to good quality ultrasound services may be difficult and expensive for some breeders. At the very least, breeding cats should be ausculted (examined by a vet with a stethoscope) for heart murmurs or arrhythmias once yearly. Any cat with an abnormality should have an echocardiogram. A significant percentage of cats with HCM will not have a heart murmur, however.
Since HCM can occur at any age, a single normal echocardiogram does not guarantee a cat is free of disease. Breeding cats should probably have an echocardiogram yearly during their breeding years.
In the long term, we will need a genetic test for HCM in each breed. A genetic test allows us to identify affected cats before they were bred and do so accurately. Since the disease is inherited as an autosomal dominant trait, once a mutation is identified, if all breeders cooperated by testing their breeding cats for the mutation the disease could be eliminated from the breed within several generations. However, the money and resources necessary to identify the gene or genes and to develop a genetic test for each breed are scarce in veterinary medicine. Breeders and cat fanciers can help by supporting research through organizations such as the Ricky Fund established by the Winn Feline Foundation.
There is no universally agreed upon definition of an HCM free cattery. The terminology is currently unclear, as different breeders mean different things when they use this term. Ideally, each breed should develop a specific definition and guidelines for use of this designation for catteries.
This article is written by the Winn Feline Foundation
Mark Kittleson, DVM, PhD, DACVIM (Cardiology)
School of Veterinary Medicine
University of California, Davis
Rebecca Gompf, DVM, MS, DACVIM (Cardiology)
College of Veterinary Medicine,
University of Tennessee
Susan Little, DVM, DABVP (Feline)
President, Winn Feline Foundation
This information is provided as a guide and is intended to educate. It is not meant to replace or supersede any veterinary or medical treatment. We ARE an HCM scanning cattery AND DO ENCOURAGE HCM scanning of your kitten between 1-2 years and then as suggested by your veterinarian. We are also an FIP negative cattery and this is on file with our veterinarian.
FIP (Feline Infectious Peritonitis)
from the ASPCA and WebMD Veterinary Reference
The following information isn’t intended to replace regular visits to your veterinarian. If you think your cat may have feline infectious peritonitis, please see your veterinarian immediately. And remember, please do not give any medication to your pet without talking to your veterinarian first.
What Is Feline Infectious Peritonitis?
Feline infectious peritonitis (FIP) is a viral disease that occurs worldwide in wild and domestic cats. It is caused by a type of virus called a coronavirus, which tends to attack the cells of the intestinal wall. In 1970, the coronavirus that causes FIP was isolated and characterized. In 1981, another coronavirus was isolated. Although this virus is nearly identical to the FIP virus, cats who were infected with it developed only very mild diarrhea and recovered easily.
The Symptoms of FIP
FIP manifests in a “wet” form and a “dry” form. Signs of both forms include a fever that doesn’t respond to antibiotics, anorexia, weight loss and lethargy. In addition, the wet form of FIP is characterized by the accumulation of fluid in the abdominal cavity, the chest cavity, or both. Cats with fluid in the chest exhibit labored breathing. Cats with fluid in the abdomen show progressive, nonpainful abdominal distension. In the dry form of FIP, small accumulations of inflammatory cells, or granulomas, form in various organs, and clinical signs depend on which organ is affected. If the kidneys are affected, excessive thirst and urination, vomiting and weight loss are seen; if the liver, jaundice. The eyes and the neurologic system are frequently affected, as well.