Cardiovascular Disorders

Animals Affected – Dog

General Information
Aortic stenosis is a congenital heart defect that is most common in German Shepherds, Newfoundlands, and Boxers. In this condition, the narrowing of the aorta (the large artery that distributes blood from the heart) forces the heart to beat faster and harder to pump blood to the rest of the body. This can lead to heart failure.

While some young puppies with aortic stenosis appear completely healthy, others tire quickly, are stunted, and have fainting spells. Sudden death at 6 to 18 months of age is common.

Dogs with mild stenosis (narrowing) may live for many years without developing heart failure, but once signs of heart failure develop, the chances for a normal life are poor.

Diagnosis of aortic stenosis frequently involves radiographs (x-rays), electrocardiograms, angiography, or echocardiography.

Important Points in Treatment

1. Many cases of aortic stenosis are correctable with open-heart surgery; however, the procedure requires a heart-lung bypass and is relatively risky and quite expensive. Therefore, the procedure is not often performed.

Animals Affected – Cat

General Information
Arterial thromboembolism is a disorder of the heart and blood of cats. It is one of several complications that occur in cats with heart damage. Blood clots (thrombi) may occur within the heart and travel through the bloodstream until they become lodged. A common site for a clot to lodge is toward the rear of the body, where the aorta divides to supply blood to the rear legs. The blood supply to one or both legs can be greatly reduced by a lodged clot, depending on where the clot is. Rear-leg lameness, pain, and cool rear legs are common signs.

Important Points in Treatment

1. Initial treatment is aimed at improving circulation to the rear limbs. Blood tests and radiographs (x-rays) are used to assess and monitor the disorder during treatment.
2. If the condition fails to improve, surgical removal of the blood clot is necessary. This requires general anesthesia.

General Information
The heart is divided into right and left sides by a septum, or wall, during embryonic development. Occasionally, holes or defects in this wall develop. If the hole occurs between the right and left upper heart chambers (atria), it is called an atrial septal defect; if it occurs between the lower chambers (ventricles), it is called a ventricular septal defect. The seriousness of the problem depends on the size of the opening or hole.

There are several possible outcomes of atrioventricular septal defects. With small defects, there may be little or no effect on heart function, and the pet may seem completely normal. In others, there may be a partial or complete closure of the defect by a portion of the heart valve. Patients with larger defects may develop congestive heart failure or low oxygen levels in the blood and exhibit bluish-colored membranes (cyanosis).

Important Points in Treatment

1. Correction of septal defects requires open heart surgery using a cardiopulmonary bypass. These operations are rare and are usually performed at major veterinary referral centers.
2. Pets with congestive heart failure can sometimes be treated effectively for long periods.

General Information
Your pet’s immune system provides the ability to resist and recover from disease and injury. This defense system regulates the production of antibodies that aid in the destruction of disease agents such as bacteria and viruses.

In autoimmune hemolytic anemia, this defense system attacks the animal’s own body tissues and red blood cells, causing severe, life-threatening anemia. Although such disruption of the immune system may be caused by infection, cancer, or other diseases, in many cases the cause is unknown. Certain drug reactions may cause autoimmune hemolytic anemia. In newborns, the disease may result from antibodies found in the first milk (colostrum) of the mother.

Important Points in Treatment

1. Autoimmune hemolytic anemia is a serious, life-threatening disease. In many cases, immediate blood transfusions are needed. Less severe cases are treated with a variety of medications. In some patients, surgical removal of the spleen or treatment with anti-cancer drugs is necessary.
2. Various laboratory tests are necessary to diagnose the condition and monitor the response to treatment.
3. Relapses are common.

General Information
Your pet’s natural body defense system is essential for good health. A part of this system produces antibodies that destroy disease-causing organisms. In autoimmune thrombocytopenia, the defense system produces antibodies that attack the animal’s own platelets (blood cells necessary for blood clotting). The result is hemorrhage in various parts of the body.

Why these antibodies are formed is not fully understood, but sometimes the process is triggered by infections or tumors. In other instances, a cause cannot be found.

Important Points in Treatment

1. Autoimmune thrombocytopenia is a life-threatening disease. Hospitalization is often necessary during the early treatment period. Various laboratory tests are needed to monitor the response to treatment.
2. Blood transfusions are necessary in some cases. Some animals require treatment with large doses of very potent drugs. Often there are side effects from various drugs used to treat this disease. The doctor will describe the normal side effects expected from drug therapy.

General Information
Cardiac arrhythmias are disturbances in the rate or rhythm of the heartbeat. There are many types of arrhythmias, and their consequences vary from mild to life-threatening. The causes of most arrhythmias are unknown.

Important Points in Treatment

1. Medication: Drugs used in controlling arrhythmias must be given on schedule. Please call the doctor if you cannot give the medication as directed or don’t know when to administer the drugs.
2. Repeated cardiac examinations, including electrocardiograms and radiographs (x-rays), are often necessary to evaluate your pet’s response to treatment. Treatment may be necessary for the rest of your pet’s life.

General Information
Congestive heart failure occurs when the heart does not pump enough blood to meet normal body needs.

Pets with congestive heart failure tire easily, are short of breath and cough deeply due to poor circulation through the lungs. They may actually lose weight, but the abdomen becomes enlarged due to fluid accumulation. The legs may also be swollen and puffy. Often these patients faint or collapse after excitement or exertion, and their tongue appears bluish-gray.

Congestive heart failure can result from heart-valve disease, heartworm infection, or heart defects present at birth.

Although congestive heart failure cannot be cured, many patients can live a comfortable life with proper medical management.

Important Points in Treatment

1. Treatment is aimed at removing accumulated fluids, improving the heart’s pumping efficiency, and decreasing the heart’s workload.
2. Radiographs (x-rays), echocardiograms, and electrocardiograms (ECG) are used to diagnose the condition and monitor the response to treatment.

Animals Affected – Cat

General Information
In dilative cardiomyopathy, the heart muscle is severely weakened and the heart enlarges or dilates. This enlargement reduces the pumping efficiency of the heart and leads to heart failure. A dietary deficiency of the essential amino acid taurine is the most common cause of this disorder in cats. Other diseases, infections, or toxic substances that damage the heart muscle can also cause dilative cardiomyopathy.

Dilative cardiomyopathy is primarily a disease of young to middle-aged cats (average is 7.5 years). Although all breeds of cats may be affected, the disorder is more common in Siamese, Abyssinian, and Burmese breeds.

Important Points in Treatment

1. Dilative cardiomyopathy is a very serious condition, particularly during the early stages of treatment. Blood clots and shock are common complications and may be fatal. After 2 to 4 weeks, if the cat’s condition is improving, the prognosis (medical forecast) is much better.
2. Medication: Giving all medications, on schedule, is extremely important. Please call the doctor if you are unable to medicate your cat as instructed.
3. Activity: Your pet should be confined indoors and no vigorous play should be allowed. Do not encourage your cat to chase objects or other pets.

Animals Affected – Dog

General Information
Dilative cardiomyopathy is the most common heart muscle disorder of dogs and usually affects large-breed dogs over 3 years of age. The heart muscle becomes severely weakened, and the heart enlarges (dilates). Enlargement of the heart reduces the efficiency of the pumping action and results in heart failure.

Although the cause of primary dilative cardiomyopathy is unknown, some cases are due to muscle damage from infections, toxic substances, other diseases, or deficiencies of the amino acid L-carnitine.

Important Points in Treatment

1. Dilative cardiomyopathy is a very serious condition. Although some affected dogs have survived 2 or more years, the overall average survival time is only 6 months.
2. Medication: Giving all medications on schedule is extremely important. Please call the doctor if you cannot medicate your dog as instructed.

General Information
Endocarditis is an inflammation of the lining of the heart and/or the valves of the heart. Usually, it is caused by an infection in another part of the body, such as the teeth, tonsils, anal sacs, or kidneys. This infection reaches the heart through the bloodstream.

Endocarditis is a serious disease and may cause death. Blood clots may develop and further complicate an already serious condition.

Important Points in Treatment

1. Treatment for endocarditis is designed to eliminate the infection. The severity of the condition and involvement of other parts of the body dictate whether hospitalization is necessary and the type of treatment used.
2. Extensive laboratory tests, including blood cultures, are used to diagnose the condition and assess the response to treatment. Chest radiographs (x-rays) and other cardiac tests may be required.
3. Medication: Give all medication as directed. Call the doctor if you cannot give the medication.

General Information
Heartworm disease is becoming more common in many parts of the United States. It is caused by the heartworm, Dirofilaria immitis. This parasite lives in the right side of the dog’s heart and the nearby large vessels (pulmonary arteries). The female worm produces large numbers of microscopic, immature heartworms that circulate in the blood. These immature worms (microfilariae) are taken up with the blood by a mosquito feeding on an infected dog. After living in the mosquito for 10 to 14 days, the microfilariae can then infect another dog that the mosquito feeds on. The feeding mosquito deposits infective microfilariae into the skin of another dog, and these enter the body through the mosquito bite wound. The microfilariae eventually travel to the heart where they develop into adult heartworms. The adult heartworms produce new microfilariae within 3 months. It takes at least 190 days from the time the dog is bitten by an infected mosquito until the dog becomes a new source of infective microfilariae.

Most cases of heartworm are diagnosed by finding the microfilariae in the blood. Sometimes, however, no microfilariae are found in the blood (occult heartworm disease). These cases are diagnosed by a combination of blood tests and chest radiographs (x-rays).

Failure to treat heartworm disease may result in heart failure and/or serious disease of the liver and kidneys. Untreated heartworm disease is usually fatal.

Important Points in Treatment

1. Treatment for heartworms consists of two phases: destruction of the adult heartworms, followed by elimination of microfilariae from the blood.
2. Before treatment, a thorough physical examination, including blood tests, chest radiographs (x-rays), and an electrocardiogram, is advised. Any underlying liver or kidney disease is usually treated first.
3. Heartworm disease is very serious, and complications may arise during and after treatment. The doctor will discuss the risks involved in your pet’s treatment.

General Information
After your pet has been treated for adult heartworms, the immature worms (microfilariae) must be removed from the blood to prevent your pet from serving as a source of infection for other dogs.

Microfilariae are eliminated with medication. After the treatment period, a blood sample will be checked. If microfilariae are still present, treatment is repeated until the blood is free of microfilariae.

After the doctor is certain that all microfilariae have been eliminated, a program of preventive medication is instituted so your dog does not become reinfected.

Animals Affected – Cat

General Information
Hypertrophic cardiomyopathy is an abnormal thickening (hypertrophy) of the heart muscle of cats. The thickening causes improper filling and impaired pumping of the heart, as well as abnormal heart rhythm. These changes result in difficult breathing and fluid accumulation in the lungs. Lack of appetite and vomiting often occur 1 to 2 days before breathing difficulties appear. In some cases, blood clots develop and may cause paralysis of one or more legs or sudden death.

The disease is most common in domestic shorthair cats, followed by domestic long hairs. Persian cats may be predisposed to the disease but Siamese, Abyssinian, and Burmese breeds are less frequently involved. Middle-aged male cats are most frequently affected.

Important Points in Treatment

1. Hypertrophic cardiomyopathy is a very serious disease. The prognosis (medical forecast) is guarded to good, depending on the response to treatment and the development of abnormal heart rhythms or blood clots.

General Information
Myocarditis is an inflammation of the heart muscle. There is a variety of causes, including viruses, bacteria, fungi, parasites, toxic substances, and allergic reactions. mild inflammations that affect only a small portion of the heart may cause no signs, while generalized inflammations may cause congestive heart failure or fatal disturbances of the heart rhythm. Determination of the cause of myocarditis is often difficult.

General Information
The developing fetus within the womb does not use its own lungs to mix blood and oxygen. Instead, it receives oxygen-rich blood from its mother through placental circulation. A blood vessel (the ductus arteriosus) in the unborn fetus bypasses the lungs to send blood to the rest of the body. Only a small amount of fetal blood flows through the lungs.

Normally, the ductus arteriosus closes within a few hours of birth. In some animals, the ductus does not close, and blood continues to bypass the lungs and not pick up oxygen. A human infant with patent ductus arteriosus is called a “blue baby.”

This defect occurs more in Poodles, Collies, Pomeranians, and Shetland Sheepdogs than in other breeds. Many affected pups die of heart failure within the first few weeks of life, but most affected pets that live to 8 weeks of age survive into adulthood. When the bypass is small, the dog may live a normal life without ever showing any ill effects. Patent ductus arteriosus also occurs in cats.

Important Points in Treatment

1. Surgical closure is the only means of correcting patent ductus arteriosus. Medical therapy helps stabilize animals with heart failure only for short periods.

General Information
The pericardium is a thin sac that surrounds the heart. Its function is to support and protect the heart. Under normal circumstances, this sac contains only a very small amount of fluid.

Pericarditis is inflammation of this sac. Pericardial effusion is a large increase in the amount of fluid within the sac. Pericardial effusion compresses the heart and decreases its pumping ability. Pericardial effusion often develops after pericarditis.

Causes of pericardial disease include heart failure, tumors, trauma to the heart or pericardial sac, bacterial toxins or infection, viral infections, and diseases that interfere with normal blood clotting.

Important Points in Treatment

1. Various laboratory tests, radiographs (x-rays), electrocardiographs (ECG), and such specialized techniques as angiography and echocardiography are often necessary to diagnose and monitor the response to the treatment of pericardial disease. Pericardial disease is always a serious problem, and successful treatment is not always possible.

General Information

Certain large blood vessels present in the developing fetus normally disappear before birth. When parts of these vessels remain after birth, they can trap the windpipe and esophagus (passage to the stomach) in a tough, fibrous ring and interfere with the normal passage of air and food.

Puppies and kittens with persistent right aortic arch eat normally but have difficulty swallowing, vomiting undigested food shortly after eating, are short of breath, and grow more slowly than their littermates. These signs usually appear just after weaning, when the young begin to eat solid foods.

Important Points in Treatment

1. Persistent right aortic arch is treated surgically by freeing the esophagus and windpipe from the encircling structures. The chances for total recovery depend on whether the esophagus has been permanently damaged and whether the nerve supply in the area is normal.

General Information
Pulmonic stenosis is a narrowing or partial obstruction of the pulmonary artery, pulmonary valve, or area of the heart adjacent to the valve that impairs blood flow from the right side of the heart to the lungs. As a result, less blood reaches the lungs, and the heart must pump harder to get blood to the lungs to pick up fresh oxygen. If the narrowing is severe, heart failure may occur because the heart itself is not receiving enough oxygen.

Most young dogs with pulmonic stenosis appear healthy, but, as they age, difficulty breathing, tiring on exercise, and fainting may occur. As the condition worsens, signs of heart failure, such as swelling of the abdomen and legs, may develop. Other signs, such as difficulty breathing, weakness, and fainting, become more noticeable.

Pulmonic stenosis usually causes heart failure before the dog reaches 3 years of age, but some dogs live a normal life if the stenosis is mild.

Important Points in Treatment

1. n some cases, surgical correction of the stenosis is possible. The doctor will advise you if surgery would be appropriate for your pet. In most instances, treatment is aimed at controlling signs of illness and prolonging life with medical and dietary treatment.
2. Radiographs (x-rays), electrocardiograms (ECG), and laboratory tests are necessary to diagnose the condition and evaluate the response to treatment.

General Information
The heart valves are one-way valves that allow blood to flow in one direction only (through the heart). If a valve does not close (valvular insufficiency), blood flows out of and then back into the heart. Valvular insufficiency may be present at birth (congenital) or can occur later because of disease.

It may affect the right, left, or both sides of the heart. Signs of left-sided heart failure include difficulty breathing, coughing, and decreased stamina. With right-sided heart failure, signs include decreased appetite, weight loss, gradual abdominal enlargement, occasional vomiting and diarrhea, and swollen limbs. In many cases, signs of both right and left heart failure are present.

Important Points in Treatment

1. Many cases of valvular insufficiency can be successfully controlled for long periods with medication. A thorough physical examination, laboratory tests, chest and abdominal radiographs (x-rays), and electrocardiograms are necessary to devise a proper treatment program. In some cases, angiography and echocardiography are also needed.

General Information
Von Willebrand’s disease is a disorder characterized by prolonged bleeding due to abnormal blood clotting. Dogs with this disease lack normal amounts of blood protein that is necessary for the blood platelets to stick together during blood clot formation. This blood protein is called von Willebrand’s factor, and the low levels are the result of a hereditary genetic defect.

While more than 25 breeds of dogs have been affected, Scottish Terriers, Doberman Pinschers, and Airedale Terriers are some of the more commonly affected breeds. Some affected dogs also have abnormally low thyroid levels.

In addition to abrasions, lacerations, or other trauma, dogs with von Willebrand’s disease may bleed in response to parasites, viral or bacterial infections, giving birth, surgery, or other physical stress.

Important Points in Treatment

1. There is no “cure” for von Willebrand’s disease. Treatment is symptomatic and depends on the severity of the bleeding episode.