Heart Murmurs in Cats

Extra heart vibrations that are produced as a result of a disturbance in the blood flow—enough, in fact, to produce audible noise—are referred to as murmurs. Often, the murmurs are classified according to a variety of characteristics, including their timing. Systolic murmurs, for example, occur when the heart muscle contracts; diastolic murmurs occur when the heart muscle relaxes between beats; and continuous and to-and-fro murmurs occur throughout all or most of the cardiac cycle.

Symptoms and Types
The symptoms associated with murmurs depend on a variety of characteristics, including their grade, configuration, and location. If, however, the murmur is associated with structural heart disease, your cat may display signs of congestive heart failure such as coughing, weakness, or exercise intolerance.

Grading Scale for Murmurs

  •  Grade I – barely audible
  •  Grade II – soft, but easily heard with a stethoscope
  •  Grade III – intermediate loudness; most murmurs which are related to the mechanics of blood circulation are at least grade III
  • Grade IV – loud murmur that radiates widely, often including opposite side of chest
  •  Grade V – very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall
  • Grade VI – very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall


  • Plateau murmurs have uniform loudness and are typical of blood regurgitation through an abnormal valvular orifice (regurgitant murmurs).
  • Crescendo-decrescendo murmurs get louder and then softer and are typical of ejection murmurs due to turbulent forward flow.
  • Decrescendo murmurs start loud and then get softer and are typical of diastolic murmurs.

Murmurs are caused by the following:

  • Disturbed blood flow associated with high flow through normal or abnormal valves or with structures vibrating in the blood flow.
  • Flow disturbances associated with outflow obstruction or forward flow through diseased valves or into a dilated great vessel.
  • Flow disturbances associated with regurgitant flow due to an incompetent valve, patent ductus arteriosus, or a defect in the septum (the wall that separates the heart’s right and left sides).

More specifically, the following are some conditions and diseases that may bring on murmurs:

  • Systolic Murmurs
  • Anemia
  • Hyperthyroidism
  • Heartworm disease
  • Mitral and tricuspid valve heart failure
  • Cardiomyopathy and aortic valve insufficiency
  • Mitral and tricuspid valve dysplasia
  • Systolic anterior mitral motion (SAM)
  • Dynamic right ventricular outflow obstruction
  • Dynamic subaortic stenosis
  • Aortic stenosis
  • Pulmonic stenosis
  • Atrial and ventricular septal defect
  • Tetralogy of Fallot
  • Mitral and tricuspid valve endocarditis (inflammation of the inner part of the heart)

Continuous or To-and Fro-Murmurs

  • Patent ductus arteriosus
  • Ventricular septal defect with aortic regurgitation
  • Aortic stenosis with aortic regurgitation
  • Diastolic Murmurs
  • Mitral and tricuspid valve stenosis
  • Aortic and pulmonic valve endocarditis (inflammation of the inner layer of the heart)

In order to determine exactly what is causing the symptoms, your veterinarian must differentiate a wide range of abnormal heart sounds—split sounds, ejection sounds, gallop rhythms, and clicks, for example. He or she must differentiate between abnormal lung and heart sounds, and listen to see if timing of abnormal sound is correlated with respiration or heartbeat.
The location and radiation of the murmur, as well as the timing during cardiac cycle, is another way to determine the underlying cause. This can be accomplished by conducting a variety of tests, including chest radiographs (x-rays), Doppler studies (blood pressure), and echocardiography. A complete blood count, meanwhile is one of the preferred methods for confirming anemic murmurs.

Unless heart failure is evident, your cat will be treated as an outpatient. The course of treatment will be determined based on the associated clinical signs. Kittens with low grade murmurs, for example, may require little or no treatment and the murmur may resolve itself within six months. Routine diagnostic imaging is recommended for cats with murmurs.
Source URL; http.//www.petmd.com/cat/conditions.cardiovascular/c_ct_heart_murmur

Hypertrophic Cardiomyopathy in Cats

The heart has four chambers: two chambers at the top, the right and left atria; and two chambers on the bottom, the right and left ventricles. The left ventricle is responsible of receiving oxygenated blood from the lungs and pumping the blood out into the aortic valve, the main artery of the body, which feeds the oxygenated blood to all parts of the body. Hypertrophic cardiomyopathy (HCM) affects the left ventricle and its functional ability to pump blood into the aorta. The normal, healthy left ventricle is already thicker than the right ventricle owing to its greater workload in pumping blood out into the body. In hypertrophic cardiomyopathy, the muscle of the left ventricle is abnormally enlarged or thickened. A cat may have other diseases of the heart, but they will be independent of HCM.

There is an apparent genetic predisposition for this condition. Some families have had a high number of cases, particularly Maine coon cats, where a mutation that is associated with the disease was identified in one large family. The role of genetics has not been definitively determined in other families or breeds, although some association has been documented in American Shorthairs and Persians.

HCM occurs more often in cats five to seven years of age, although the age range reported cases ranges from three months to 17 years, with most cases affecting males. Heart murmurs in older cats are generally caused by hyperthyroidism or hypertension rather than HCM.
Symptoms and Types

  •  Loss of appetite (anorexia)
  •  Lethargy
  •  Weak pulse
  •  Difficulty breathing
  •  Short, rough, snapping breathing sounds (crackles)
  •  Abnormal heart sounds (i.e., muffles, galloping rhythm, murmurs)
  •  Inability to tolerate exercise or exertion
  •  Sudden hind-limb paralysis with cold limbs due to clot in the terminal aorta
  •  Bluish discoloration of foot pads and nailbeds (indicates a lack of oxygen flow to the legs)
  •  Collapse
  •  Sudden heart failure

The cause for HCM may remain unknown in many cases. However, genetic mutations and predispositions are known to head to HCM in cats. And though not a direct cause of the condition, hypertension and/or hyperthyroidism can further complicate HCM in cats.
Your veterinarian will need a thorough history of your cat’s health leading up to the onset of symptoms, including any information you have about your cat’s genetic background.
An electrocardiogram (or EKG) recording can be used to examine the electrical currents in the heart muscles, and may reveal any abnormalities in cardiac electrical conduction (which underlies the heart’s ability to contract/beat), and can also help your veterinarian to determine the origin of the abnormal heart rhythms, if they are present. However, and EKG may not be adequate for a definitive diagnosis. Radiograph and echocardiograph (ultrasound) imaging will be more useful for visually examining the heart for enlargement or thickening of the walls, or for thickening of the mitral valve (which controls the flow of blood between the left ventricle and the left atrium). Other conditions will need to be either ruled
out or confirmed before your doctor settles on HCM. There are two conditions, which are especially likely to mimic HCM that your cat will be checked for. Blood pressure will be checked in order to rule out hypertension, and the blood will be tested for high levels of thyroid hormones. Hyperthyroidism will exhibit many of the same symptoms as HCM, such as lethargy, shortness of breath and irregular heart rhythm.
If there is a diagnosis of HCM, your cat will be hospitalized for appropriate care, especially if it is suffering from congestive heart failure, a common outcome of this disease. Your cat will be placed in a quiet environment to minimize stress, and if it is having trouble breathing it will be given oxygen therapy.

There are several possible medications that can be used to treat HCM:

  •  Diltiazim to slow the heart rate, treat irregular heartbeats, and possibly reduce the enlargement in the left ventricle
  •  Beta blockers to slow the heart rate, correct irregular heartbeats, and control blockage of the blood flow. These are not used if the cat has congestive heart failure.
  •  Ace inhibitors, in cases with congestive heart failure, to improve the flow through the ventricle
  •  Aspirin to decrease risk of blood clots
  •  Warfarin to prevent blood clots
  •  Furosemide (diuretic) to remove excess fluid from the body
  •  Spironolactone (a diuretic used sometimes in conjunction with furosemide) for cats with congestive heart failure
  •  Nitroglycerin ointment, to improve flow by dilating (opening) the ventricle and arteries

Living and Management
The cat should be put on a sodium-restricted diet, especially if there is congestive heart failure, to keep the pressure in the blood stable. Providing a quiet and safe space for your cat, away from other pets and active children, is important to its recovery. Environmental stress may activate the nervous system, placing excess stress on the already overstressed left ventricle, and possibly lead to heart failure.
You will need to monitor your cat closely during the recovery period, watching for difficulty breathing, lethargy, weakness, lack of appetite, and painful hind-limb weakness or paralysis. Periodic diagnostic testing (such as repeat echocardiogram) and bloodwork will be necessary (to monitor kidney function and electrolytes).
Source URL: http://www.petmd.com/cat/conditions/cardiovascular/c_ct_cardiomyopathy_hypertrophic

proBNP Testing in Cats

The cat’s heart increases production and secretion of BNP, B-type natriuretic peptide hormone, in response to excessive stretching of heart muscle cells, which is common in many forms of heart disease and heart failure. The magnitude of the increase in circulating BNP is correlated to the severity of the underlying heart disease. A diagnostic test is available, the feline NT-proBNP, which can measure this hormone.

Cats with respiratory signs such as shortness of breath (dyspnea), rapid breathing (tachypnea), and cough may be associated with underlying heart disease such as cardiomyopathy and congestive heart failure, or a primary respiratory disease such as bronchitis/asthma, pneumonia, pleural effusion, and so on. At times it is unclear if the respiratory symptoms are related to cardiac (heart) or pulmonary (lung) disease, especially if the physical exam and chest x-rays are ambiguous. In such cases, a proBNP test may help guide further diagnostic testing and therapy. The proBNP is not a stand-alone test but can be valuable when included with other diagnostic testing such as chest x-rays and echocardiogram.

Feline Heart Disease

Heart disease in domestic cats is actually quite common, which may come as a surprise to feline owners. It can strike any age or any breed of cat. One of the most challenging aspects of feline heart disease is that cats may not show any warning signs (such as exercise intolerance, coughing, weakness)until the process is very advanced. This means that a cat can literally be playing vigorously one day, and suddenly have trouble breathing. Untreated heart disease often progresses to heart failure, blood clot formation, and death.

The detection of a new heart murmur by your veterinarian (often on routine examination) can be the first sign that changes in the heart have taken place. While not every murmur signals the onset of heart disease, a further investigation is warranted since those murmurs which are a result of heart disease cannot be distinguished from "innocent" murmurs by routine tests alone.

Fortunately, advances in companion animal medicine enable veterinarians to efficiently diagnose cardiovascular disease in cats, even in its early stages. In many instances, if heart disease is detected prior to the stage of actual heart failure, it can be successfully controlled with medication(s). A feline with carefully controlled heart disease may live symptom-free for years!


The first test for heart disease begins with a thorough physical examination. During the exam, the veterinarian will determine your cat's heart rate and rhythm. A persistently elevated rate, or a rhythm that is irregular can be associated with heart disease in cats. The presence of a murmur (especially one not previously detected) may be further evidence of heart disease. In advanced cases of heart disease, abnormal sounds in the lungs may be heard. A weak or irregular pulse can also occur. The results of the physical exam may lead to further testing.

Chest Radiographs (x-rays)

Chest radiographs are important components in the diagnosis of feline heart disease. A diseased heart will most often enlarge over time. In advanced stages, fluid may be detectable in the chest cavity (pleural effusion) or in the lungs themselves (pulmonary edema).

Electrocardiogram (EKG or ECG)

An electrocardiogram (EKG or ECG) is a tracing of the electrical activity of the heart. It documents heart rate and rhythm. In addition, subtle changes can occur in the shape of the ECG spikes that can reveal certain types of pathological changes in the heart. It is a rapid and painless test that can be performed in the veterinary office.


An echocardiogram, also known as a cardiac ultrasound exam, is one of the most advanced and sensitive tests for determining the presence of heart disease in animals. It is painless and generally does not require sedation. The technique uses sound waves to actually visualize the heart in action. From this exam, the dimensions of each heart chamber can be determined.

Ultrasound can also detect the presence or absence of fluid in the sac around the heart (pericardial effusion), fluid in the chest, congenital heart defects, abnormalities of the heart valves, blood clots within the heart itself, or heart tumors (rare in cats). Most importantly, the echocardiogram can actually determine the type and degree of heart dysfunction. An accurate assessment of heart disease is paramount to effective treatment.


Dilative cardiomyopathy

Dilative cardiomyopathy denotes heart disease that results in an enlarged heart with thinning and weakening of its muscular walls. The weakened heart cannot pump efficiently which subsequently can lead to fluid accumulation in the lungs and/or chest cavity (analogous to congestive heart failure in humans). Enlargement of the heart can lead to leakage at the heart valves, creating a murmur.

This form, although more difficult to successfully control, has become less common in recent years. A few years ago, research showed that deficiency of the amino acid taurine in the feline diet was one of the main causes of dilative cardiomyopathy. Since that time, most commercially made feline diets are supplemented with taurine.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is the most commonly diagnosed heart disease in cats. The walls of the heart become much thicker and stiffer than normal. This results in a smaller chamber to hold the blood, and diminishes the amount of blood pumped out with each beat. Consequently, the heart has to accelerate and use more energy to accomplish its original task. The geometric changes in the heart can lead to leakage at the valves, and development of a murmur. As the disease progresses, the heart can become so thickened that it cannot pump the blood forward at an adequate rate. This usually results in fluid accumulation in the lungs.

The cause in most cases is unknown, but genetics are thought to play a role in at least some cat breeds. While it is most common in middle-aged male cats, it can be seen in either sex as early as 6 months of age. Hypertrophic cardiomyopathy remains the most treatable form of feline heart disease.

Restrictive cardiomyopathy

Restrictive cardiomyopathy is a less common, less defined type of heart disease in cats. It is more difficult to detect, as many cats will have near normal echocardiograms, but their heart walls seems "stiffer" and less efficient at pumping blood forward. It is thought that in such cats the heart wall muscle cells become slowly replaced with less functional scar tissue. Cats with this type of disease may shows signs consistent with either dilative cardiomyopathy, hypertrophic cardiomyopathy, or both.


Therapy for feline heart disease depends on which type is diagnosed and how advanced the disease is. As previously mentioned, cats with hypertrophic cardiomyopathy have the best long term outlook The most serious consequences of progressive heart disease are weight loss, anorexia, difficulty breathing, weakness, and blood clot formation (with possible limb paralysis). Cats with advanced heart disease are at risk for sudden death.

Early detection and intervention, however, can be very rewarding for many cats and their owners.


Furosemide (Lasix‰) is a diuretic ("water pill") used in all types of feline heart disease. It reduces the volume of fluid that the heart has to pump, and removes fluid from the lungs. This makes the heart's work easier.


Enalapril (Vasotec¨ or Enacard‰) is a drug known as a vasodilator. It is very useful in many types of heart disease. It lowers blood pressure and reduces the workload of the heart. In dilating the vessels downstream from the heart, it lowers the resistance to blood being pumped forward.


Diltiazem (Cardizem‰) is a drug used in humans and animals. It is a "calcium channel blocker." Most commonly used for hypertrophic cardiomyopathy, it reduces the stiffness and work of heart walls. It has been documented to prevent or reverse wall thickening in many cats, and is very well tolerated.


Digitalis (Digoxin® or Lanoxin®) is a very old but useful drug utilized in people and animals mainly for treatment of dilative cardiomyopathy. It strengthens the contraction of the heart muscle with the goal of improving pumping function. It also can correct certain types of irregular heart rhythms. Because it has a narrow safety range, the drug concentrations in the patient's bloodstream must be monitored periodically.


Betablockers such as propranolol (Inderal®) or atenolol (Tenormin®) are prescribed mainly for hypertrophic cardiomyopathy. These drugs slow the rhythm of the heart, allowing the attenuated chambers to fully fill with blood between heartbeats. This increases cardiac output and thus reduces the actual work of the heart. Betablockers also lower blood pressure and regulate heart rhythms.


One of the health risks for feline heart disease patients is the formation f a blood clot in the heart. The clots can form in the enlarged heart chambers where the blood undergoes increased turbulence. If a piece of the clot leaves the left side of the heart and travels downstream, it often lodges in the large blood vessel known as the aorta. Since the aorta is the trunk artery carrying blood to the back half of the body, loss of this blood flow can cause temporary or permanent paralysis. The best prevention of this complication is to 1) adequately control the heart disease and reduce heart chamber size and 2) low dose aspirin therapy. While cats can have toxic or lethal reactions to high dose aspirin or any dose of acetaminophen (Tylenol®), low dose aspirin can often be used safely. The usual dose is 1/4 of an adult regular aspirin or 1 baby aspirin (81 mg.) per cat TWICE WEEKLY.

Congenital Heart Disease

Your pet was born with a congenital heart defect. Congenital defects are abnormalities that occur in the developing fetus and are usually recognized soon after birth. If the defect is too sever, the embryo dies before birth. Other situations, not as sever, allow embryo development to birth, and the pet can live until the defect interferes with normal functioning (here, the cardiovascular system). Most congenital defects are first recognized at or near the time of weaning when the pet is taken to the veterinarian for a first examination. Sometimes these problems may not be identified until later in life. Congenital defects are most often the result of abnormalities in the genetic makeup of the pet. The abnormal genes may or may not be present in other members of the litter but are carried by the mother and/or father, sometimes without compromising their health. Other causes of congenital defects include exposure to radiation, toxins, or physical events that occurred during the animal's embryonic stage.

There are numerous ways to classify congenital heart defects, but for simplicity we will consider them in four major categories: (1) obstruction of blood flow within the heart: (2) abnormal communication between the two sides of the heart, increasing the blood flow from the left (systemic) to the right (lung) side of the heart: (3) abnormal communications sending blood in the opposite direction of flow, from the right (lung) to the left (systemic) side of the heart: and (4) vessel (vascular) abnormalities that obstruct a body part and interfere with normal function.

Obstruction of blood flow within the heart includes conditions such as pulmonic, mitral, or aortic valvular stenosis. Valvular obstruction is caused by a narrowing of an area of blood flow, decreasing circulation from the heart to some part of the body. These conditions vary from mild to severe. They may be minimal and require no care. However, in other cases, medication only, opening the obstruction with a special catheter, or surgical correction may be needed. Surgery, although commonly performed in humans, is both difficult and infrequent in veterinary medicine.

Blood may flow abnormally from the left to the right side of the heart because of a hole between the two sides of the heart that did not close during embryonic formation. One such condition, patent ductus arteriosus (PDA), is a remnant of normal embryonic heart function. If PDA is diagnosed early, it may be corrected surgically and the pet may be able to lead a normal life. Other conditions such as ventricular or atrial septal defects involve a hole between two chambers of the heart. Closure of septal defects requires open heart cardiopulmonary bypass surgery, which is infrequently performed in veterinary medicine. Blood flow from the right to the left side of the heart without passing through the lungs is very abnormal and quite uncommon. Thus, a serious communication problem exists that results in unoxygenated blood being transported to the body. Such a situation usually does not allow the pet to live beyond early adulthood. Because of the complicated nature of these problems, open heart surgery is rarely an available option. Surgical procedures may be available at teaching and specialty clinics to treat such problems.

Persistent aortic arch, peripheral arteriovenous shunts, and cor triatriatum are heart problems that are the result of abnormal vessels interfering with normal blood flow. These conditions can usually be corrected surgically if identified early, before complicating problems develop to preclude normal life.

Because many congenital heart defects are thought to be due to genetic problems that can be passed from one generation to the next, veterinarians recommend that animals with such conditions be neutered at an early age to prevent breeding and the dissemination of defective genes to a new generation. Some congenital heart defects may be surgically corrected; others are effectively dealt with for variable periods using medications. Regrettably, most congenital heart defects have a poor long-term prognosis. It is sad for the owner and for the pet to suffer needlessly. In selected circumstances, euthanasia may be recommended if the pet is unable to maintain a good quality of life.

A congenital heart defect is suspected after a thorough physical examination has been performed. The electrocardiogram helps to identify the presence of abnormal heart chamber size as well as irregularities of the heart's rate and/or rhythm. Radiographs (x-rays) are needed to visualize abnormalities in the size and appearance of the heart, vessels, and lung structures. The ultrasound (echocardiogram) examination is a direct, noninvasive means of looking inside the heart's walls to measure the size of the heart's four chambers and to identify abnormalities (qualitatively and quantitatively) in blood flow. Occasionally, more invasive procedures such as cardiac catherization (passing small tubes into the heart and blood vessels and injecting dye) or surgical evaluation may be recommended.


SOURCE: Textbook of Veterinary Internal Medicine, Client Information Series, by Stephen J. Ettinger.


Cardiac Evaluation of the Canine Athlete

A healthy heart is essential to successful performance for any athlete and this is certainly true of canine competitors. Heart disease in dogs may be present since birth (congenital conditions) or may be acquired later in life. Dogs can develop abnormalities of the heart valves or heart muscle, as well as structural deformities. Clinical signs of heart disease in dogs include exercise intolerance, fatigue, shortness of breath, fainting, discoloration of the gums, coughing and restlessness, particularly at night. Upon physical examination, a veterinarian may detect abnormalities such as a heart murmur, an abnormal heart rhythm, or a rapid or slow heart rate. If heart disease is suspected, a consultation with a veterinary cardiologist is strongly recommended in order to further define the extent of the problem. This is particularly important with working dogs and those that are actively involved in competition. A thorough cardiac evaluation is also recommended for young dogs that are about to enter into competition for the first time.

Cardiac evaluation begins with a complete physical examination and auscultation of the heart with a stethoscope. Further assessment is performed using a series of specialized diagnostic tests. These include thoracic radiographs (chest x-rays), an electrocardiogram (ECG), and an ultrasound examination of the heart, referred to as echocardiography. These tests provide different pieces of information about the overall health of a dog's heart.

Chest x-rays provide direct information regarding the size of the heart and the condition of the lungs. The larger vessels entering and leaving the heart can also be evaluated. In cases of heart failure, fluid accumulation can be detected. When x-rays are repeated over a period of time, they can help judge the effectiveness of treatment.

An electrocardiogram is a test used to record the electrical activity of the heart and to detect abnormal heart rhythms called arrhythmias. The ECG can also provide information regarding enlargement of specific chambers of the heart and the position of the heart in the chest cavity.

Echocardiography is a highly specialized, non-invasive test that allows the veterinary cardiologist to "see" inside the heart using a form of sonogram. An ultrasound probe is placed on the chest and sound waves are used to assess heart structure, chamber size, and heart valves. The ultrasound exam allows for evaluation of functional abnormalities such as weak heart muscle contractions or incompetent heart valves. A specialized test called "color flow Doppler" provides greater detail about the blood flow through the heart. This test is discussed in more detail elsewhere in this issue (see page 5).

When these tests are performed on a canine athlete, they provide complete information regarding the dog's heart. If no abnormalities are detected, the dog is cleared of any limitations due to cardiac disease. In cases where one or several tests are abnormal, the veterinary cardiologist will interpret the information and formulate a treatment plan.


Canine Valvular Insufficiency and Congestive Heart Failure

An electrocardiogram (ECG) can identify heart enlargement or irregularities of the heart's rhythm. Radiographs (x-rays) can demonstrate heart enlargement and/or inappropriate fluid accumulation. Blood testing can identify hormonal, kidney or other internal medical problems. An ultrasound examination (echocardiography) accurately pictures enlarged heart chambers, abnormalities

Valvular insufficiency occurs when damaged and thickened valves develop within the heart of small and midsize dogs. Valve problems are unusual in larger breed dogs and in cats but they may develop. In the small breeds of dogs, valvular insufficiency begins in midlife and progresses slowly. The disease is associated with thickening and shortening of the valve components that separate the upper (atria) from the lower (ventricles) parts of the heart. Remember, normally blood flows in only one direction. If the valves fail to close completely when the heart contracts, blood moves forward but some leaks backward. Clinical signs vary depending on whether the right and/or left side of the heart is affected and whether heart enlargement presses on the windpipe. Fluid accumulates when the heart fails to pump enough blood to the body and instead the blood is transmitted backward from the heart to the lung or body.

Owners of pets with valve problems see inappropriate panting, heavy breathing, diminished exercise ability, fatigue, cough, and occasionally fainting. The cough usually starts at night and progresses to daytime as well, particularly when associated with exercise. Retching and nonproductive gagging follow the cough. When the right side of the heart is affected fluid may accumulate around the lungs, making it difficult to breathe, and in the abdomen, making it swell.

A number of treatments are used for pets with valvular heart disease, including exercise restriction. Walking is good exercise. Digitalis is a medication used to strengthen the heart and to treat some irregularities of its rhythm. It maintains a slower and more effective heart muscle contraction. Signs of digitalis excess include loss of appetite, lethargy, vomiting, and diarrhea. ECG monitoring permits the veterinarian to supervise your pet's progress. Diuretic agents are commonly given to remove excess water accumulation from the body and can cause increased water drinking and urination. Diuretics can induce weakness, dehydration, and blood salt abnormalities. Alterations in electrolytes (salt) levels are identified through periodic testing of your pet's blood. Angiotensin-coverting enzyme inhibitors (ACEI 's) are drugs that improve the bodies ability to reduce salt and water retention, to reduce high blood pressure, and to limit the effect of hormones that adversely affect heart muscle. Given in excess, ACEI drugs cause malaise, blood salt disturbances, loss of appetite, and possibly kidney damage. Antiarrhythmic agents may be given to stabilize the cardiac rate and rhythm. Drugs to decrease blood pressure and nutritional supplements may be required for specific conditions.

In order to control the symptoms of heart failure, low-salt (sodium) diets may be suggested. Excess sodium is normally removed by the kidney, but this does not occur as effectively in heart failure. Commercial low-salt diets, varying from moderate to extreme restriction, are effective in preventing salt and water retention. These diets are recommended only after heart failure has been diagnosed. A modest reduction in salt intake may be indicated before the onset of heart failure. If your pet refuses to eat a commercial diet, low-salt foods can be prepared by the owner under veterinary direction. It is important to emphasize that mixing low-salt diets with regular (high-salt) diets or feeding snacks high in sodium is not recommended.

Longevity and quality of life in dogs with this disease vary with the severity of the valve damage and the amount of blood leakage into the upper chambers of the heart. Concurrent medical conditions, age, and the physical status of the pet play a large role in determining the animal's prognosis. Clinical signs are progressive, and although they may be decreased, they never entirely resolve. Medical therapy can enhance the quality of life of the pet as well as increase life expectancy. Dogs with left-sided valvular heart disease treated with medication and a low-salt diet have an average life expectancy of about 9 months from the time heart failure begins. Abdominal fluid accumulation and body emaciations are signs of right-sided heart failure. Regularly removing the extra fluid may increase life expectancy. Surgical replacement of the valves is not an option in dogs at this time.


Source: Textbook of Veterinary Internal Medicine, Client Information Series, by Stephen J. Ettinger