Puggles

Chronic Valvular Disease

This common heart disease of unknown cause affects 20 to 40 percent of dogs. It occurs most often in toy and small breed dogs, particularly Cavalier King Charles Spaniels, Miniature and toy Poodles, Chihuahuas, Lhasa Apsos, Yorkshire Terriers, Schnauzers and Cocker Spaniels. Chronic valvular disease is characterized by degenerative changes in the heart valves. The mitral valve is affected in nearly all cases; the tricuspid valve in about one-third of cases. The valve leaflets become thickened and distorted so that the free edges of the valves no longer make contact. The cords that attach the valve leaflets to the lining of the heart may rupture, allowing the valve to flap in the bloodstream. These changes result in loss of valve function and a fall in cardiac output. When the ventricles contact, some blood is ejected backward into the corresponding atrium. This is called regurgitation. Regurgitation increases the blood pressure in the atrium and causes it to enlarge. Because the mitral valve is  invariably involved, chronic valvular disease is also sometimes called mitral valve disease or mitral regurgitation. The hallmark of chronic valvular disease is a loud heart murmur heard over the left side of the chest. A chest X-ray, EGG and echocardiogram may show an enlarged left atrium, thickened valves or a ruptured cord (muscle band). If the tricuspid valve is involved, there will be a loud heart murmur heard over the right side of the heart. It is important to exclude heartworms as a cause of a right-sided heart murmur. Signs of congestive heart failure can be attributed to low cardiac output and lung congestion. They include a cough that occurs after exercise and/or is worse at night; lethargy and tiring easily; and fainting spells often related to cardiac arrhythmias.

Dilated Cardiomyopathy

Dilated Cardiomyopathy is a disease in which the heart chambers enlarge and the walls of the ventricles become thin. The heart muscle weakens and begins to fail. Dilated cardiomyopathy is the most common cause of congestive heart failure in large and giant breed dogs. It is rare in toy breeds and small dogs. A high incidence is found in Boxers, Doberman Pinschers, Springer Spaniels and American and English Cocker Spaniels. Other breeds affected include German Shepherd Dogs, Great Danes, Old English Sheepdogs, Saint Bernards and Schnauzers. Most dogs are 2 to 5 years of age at the onset of symptoms. The majority are males. In most cases the cause of dilated cardiomyopathy is unknown. Myocarditis, an inflammation of the heart muscle, may precede dilated cardiomyopathy in some dogs. Hypothyroidism has been associated with dilated cardiomyopathy. A genetic or familiar basis has been proposed for giant and large breed dogs. Cardiomyopathy related to taurine and/or carnitine deficiency is seen in American Cocker Spaniels, Boxers and possibly Golden Retrievers, Newfoundlands and other breeds. The signs of dilated cardiomyopathy are the same as those of congested heart failure and cardiac arrhythmias. Weight loss can occur in a matter of weeks. Affected dogs are lathargic, tire easily, breathe rapidly and cough frequently, sometimes bringing up bloody sputum. Coughing is especially common at night. A swollen abdomen (called ascites) may be noted. Cardiac arrhythmias can cause weakness and collapse the heart. The diagnosis of dilated cardiomyopathy is based on ECG changes showing cardiac arrhythmias, a chest X-ray showing enlarged heart chambers and an echocardiogram showing the characteristic pattern of a failing heart muscle.

Congenital Heart Disease

All forms of congenital heart disease occur in dogs. The most common defects are valve malformations (called dysplasias), valve narrowing (stenosis) abnormal openings between the heart chambers (septal  defects), patent ductus arteriosis and Tetralogy of Fallot. Patent ductus arteriosis is a persistent arterial connection between the aorta and pulmonary artery that normally closes at birth or shortly thereafter. In the uterus, the ductus plays an important role in shunting blood away from the non-functioning lungs. Many large and small breeds are affected by patent ductus arteriosis. This murmur can often be felt through the body wall - it feels like a washing machine churning. Tetralogy of Fallot is a congenital defect of the heart consisting of four abnormalities that result in insufficiently oxygenated blood pumped to the body. Most dogs with congenital heart defects die within the first year of life. Dogs with moderate defects may survive but usually exhibit exercise intolerance, fainting episodes and stunted growth. In these individuals, heart failure can occur suddenly and unexpectedly. Dogs with mild valvular disease or small septal defects are often  asymptomatic; the only indication of a congenital heart defect is a heart murmur discovered on a physical examination. The diagnosis of congenital heart defect is based on ECG, chest X-rays and echocardiogram. An ultrasound study called Doppler echocardiography measures the velocity and direction of blood flow in the heart chambers. This information makes the diagnosis of congenital heart defects extremely accurate.

Breed Predisposition for Congenital Heart Defects
Atrial septal defects	Samoyed
Ventricular septal defects	Bulldog
Aortic and subaortic stenosis	Newfoundland, Golden Retriever, German Shepherd, Rottweiler, Boxer, German Shorthaired Pointer, Samoyed
Tricuspid dysplasia	Labrador Retriever, Great Dane, Weimaraner, German Shepherd Dog
Mitral dysplasia	Great Dane, Bull Terrier, German Shepherd Dog
Patent ductus arteriosis	Poodle, Pomeranian, Collie, Shetland Sheepdog, German Shepherd Dog, Cocker Spaniel, English Springer Spaniel
Pulmonic stenosis	Beagle, Labrador Retriever, Cocker Spaniel, Schnauzers, Newfoundland, Rottweiler
Tetralogy of fallot	Keeshond, English Bulldog, Miniature Poodle, Mini Schnauzer

It is important to identify affected individuals when treatment is most likely to be successful and before the dog is used for breeding. The best time to screen puppies for congenital heart defects is when they are 6 to 8 weeks of age, before being released to their new homes. Screening is done by carefully listening for murmurs with a stethoscope over the four valve areas. The examination is best performed by a trained professional who is experienced in recognizing heart murmurs. Murmurs heard at this age may not be associated with disease; some will disappear as the pup matures. If the murmur is present at 16 weeks, however, the puppy should be screened using cardiac ultrasound. OFA maintains a cardiac registry to gather data on congenital heart defects. Dogs are screened at 12 months of age or later by a board-certified veterinary cardiologist, and if they are found to be unaffected, they are issued a certificate and a registration number. For bloodlines with an increased incidence of congenital heart defects, it is highly desirable to seek OFA certification before selecting breeding animals.

Bacterial Endocarditis

Bacterial endocarditis is an infection of the heart valves and the lining of the heart. The disease is not common. It is caused by bacterial species that gain entrance to the circulation system through wounds and infections elsewhere in the body. In many cases the actual source of infection is unknown . Dogs on corticosteroids and immunosuppressant drugs are at an increased risk, as are mid-size and large dogs. As the bacteria invade the heart valves, they produce ulcerations and small wartlike bumps called vegetations. The affects on the valves are similiar to those of chronic valvular disease. In addition, parts of infected vegetation can break off and spread the infection to other organs. This seeding process causes a variety of signs, including fever, shaking, chills, swollen joints, lameness, spontaneous bleeding, blindness and behavioral and personality changes, unstable gait, stupor and seizures. These signs are non-specific and may suggest a number of other diseases. The presence of a heart murmur, particularly a new or changing murmur, suggests a diagnosis of bacterial endocarditis. This can be confirmed by ECG, chest X-rays and echocardiography. Blood cultures identify the causative bacteria.

Myocarditis

Myocarditis is an inflammation of the heart muscle. It is an uncommon cause of heart disease in dogs. Myocarditis occurs with American trypanosomiasis, lyme disease, viral diseases including distemper and bacterial, fungal and protozoan infections. Parvovirus produces a fatal form of myocarditis in neonatal puppies. One of the first signs of myocarditis is weakness and fainting caused by cardiac arrhythmias. It can also be suspected by the sudden appearance of congenital heart failure, along with abnormal findings on an ECG and echocardiogram. If necessary, the diagnosis can be confirmed by a heart muscle biopsy. This must be done at a medical center.

Arrythmias

Arrythmias are irregular or erratic heartbeats. Normally the heart beats at a steady, regular pace. This changes with activity or rest, but is always almost a regular rhythm. Abnormal rhythms may be slower than normal (called bradycardia) or faster than normal (called tachycardia). Sometimes the speed or rate  may be normal but the heart beats follow an abnormal path through the heart muscle. Many things may cause irregular heart rates and rhythms, including increased potassium, hormonal influences, certain cancers such as hemangiosarcoma and heart diseases such as cardiomyopathy. Affected dogs may show anxiety, weakness, lathargy or even faint. To diagnose these problems, your dog may need an EKG (electrocardiogram, sometimes also called ECG) and possibly a cardiac ultrasound evaluation. Your doggy doctor may decide to have your dog wear a special heart monitor for 24 hours if the abnormality is infrequent.

Congestive Heart Failure

Congestive heart failure is the inability of the heart to provide adequate circulation to meet the body's needs. It is the end result of a weakened heart muscle. The health of the liver, kidneys, lungs and other organs is impaired by the circulatory failure, resulting in a problem involving multiple organs. A diseased heart can compensate for many months or years without signs of failure. When failure does occur, it may appear suddenly and unexpectedy, sometimes immediately after strenuous exercise, when the heart is not able to keep up with the body's demands. In toy and small breed dogs, chronic valvular disease with mitral regurgitation is the most common cause of congestive heart failure. In large breed dogs it is dilated cardiomyopathy. The early signs of congestive heart failure are tiring easily, a decrease in activity level and intermittent coughing. The coughing occurs during periods of excertion or excitation. It also tends to occur at night, usually about two hours after the dog goes to bed. Dogs may be restless-pacing instead of settling down to sleep. These early signs are non-specific and may even be considered normal for the dog's age. As heart failure progresses the dog develops other signs, such as lack of appetite, rapid breathing, abdominal swelling and a marked loss of weight. Because the heart no longer pumps effectively, blood backs up in the lungs, liver, legs and other organs. Increased pressure in the veins causes fluid to leak into the lungs and peritoneal cavity. Fluid in the lungs is the cause of the coughing. A rapid accumulation of fluid in the small airways can cause the dog to cough up a red bubbly fluid, a condition called pulmonary edema. Pulmonary edema indicates failure of the left ventricle. With failure of the right ventricle, fluid leaks into the abdomen, giving the belly a characteristic swelling or potbellied appearance (called ascites). This may be accompanied by swelling of the legs (dependent edema). An accumulation of fluid in the chest cavity (pleural effusion) also occurs with right-sided heart failure. In the late stages of congestive heart failure the dog sits with his elbows spread and his head extended. Breathing is labored. The pulse is rapid, thready and often irregular. The mucous membranes of the gums and tongue are bluish gray and cool. A thrill may be felt over the chest. Fainting can occur with stress or excertion. An accurate diagnosis is established through chest X-rays, ECG, echocardiography and other tests (such as a heartworm antigen test) as indicated.

Heartworms

Heartworm disease, so named because the adults live in the right side of the heart, continues to be a major problem for many species of animals. Heartworms are spread by mosquitoes and thus are found throughout the world. In the United States the prevalence is highest along the southeastern Atlantic and Gulf Coasts, but heartworm has been found in all 50 states. The disease is less prevalent at higher elevations. The highest infection rates (up to 45 percent) in dogs not maintained on heartworm preventive, are observed within 150 miles of the Atlantic Coast from Texas to New Jersey and along the Mississippi River and its major tributaries. Other areas of the United States have lower incidence rates (5 percent or less) of canine heartworm disease, while some regions have environmental misquito and dog population factors that combine for a higher incidence of heartworm infection. The infection rate in male dogs is as much as four times that of female dogs and dogs housed outdoors are four to five times more likely to be infected than indoor dogs. Although there are differences in frequency of infection for various groups of dogs, all dogs in endemic regions should be considered at risk and placed on prevention programs and diets.

Heartworm Life Cycle

Knowledge of the life cycle of this parasite (dirofilaria immitis) is needed to understand how to prevent and treat it. Infection begins when L3 infective larvae in the mouth parts of a mosquito enter the dog's skin at the site of a bite. The larvae burrow beneath the skin and undergo two molts that eventually lead to the development of small  immature worms. The first molt (L3 to L4) occurs one to 12 days after the dog is bitten by the mosquito. The larvae remain in the L4 stage for 50 to 68 days and then molt into L5 stage (immature worms). It is only during the brief L3 stage, 1 to 12 days after the larvae enter the dog's body, that they are suseptable to the killing affects of diethylcarbamazine. However, throughout the L3 and L4 stages the larvae are suseptible to three other drugs: ivermectin, selamectin and milbemycin. Immature worms make their way into a peripheral vein and are carried to the right ventricle and the pulmonary arteries. Approximately six months after entering the dogs body, they mature into adults. Adults can grow to 4 to 12 inches (10 to 30cm) long and live up to 5 years. As many as 250 worms may be found in a heavily infested dog. Sexual reproduction occurs if worms of both sexes are present. Females give birth to live young called microfilaria; 5,000 microfilariae can be produced in one day by a single worm. Microfilaria are able to remain alive in the dog's circulatory system for up to three years. Before the microfilariae can become infective to another dog, the L1 larvae must go into a secondary host, the mosquito This occurs when the mosquito bites the dog. The L1 larvae in the mosquito  molt to L3 larvae. In warm southern climates this process takes less than 10 days; in northern climates it can take up to 17 days. The L3 larvae then move to the mouthparts of the mosquito and are ready to infect a new host.

Heartworm Disease

When there are fewer than 50 adult worms in the average-size dog, the worms live primarily in the pulmonary arteries and the right ventricle of the heart. When the numbers are greater than 75, the worms usually extend into the right atrium. With a heavier infestation, the worms may migrate into the superior and inferior vena cavae and the veins of the liver. Worms in the lungs can migrate into the terminal branches of the pulmonary arteries, where they obstruct the flow of blood and cause the vessels to clot. This is known as pulmonary thromboembolism. Even after treatment, dead worms can be carried by the bloodstream into the pulmonary circulation, resulting in a similar severe and sometimes fatal reaction. Chronic pulmonary thromboembolism causes loss of lung tissue and right-sided congestive heart failure. Dogs with thromboembolism may cough up bloody sputum. Worms entwined about the heart valves can interfere with the mechanics of the heart and produce effects similar to those of chronic valvular disease. Worm clumps in the vena cava or hepatic veins are responsible for a condition called vena cava syndrome, which causes liver failure with jaundice, ascites, spontaneous bleeding, and anemia. Collapse and death can occur in two to three days.

Diagnosis

The signs of heartworm disease depend on the number of worms and the size of the dog. Dogs with a light infestation involving only a few worms may remain asymptomatic. The typical early signs of heartworm infestation are tiring easily, exercise intolerance and a soft deep cough. As the disease progresses these symptoms become more severe and the dog loses weight, breathes more rapidly and may cough after exercise to the point of fainting. The ribs become prominent and the chest starts to bulge. Acute vena cava syndrome or episode of thromboembolism can lead to collapse and death. A number of blood tests are available to diagnose heartworms. The most accurate is the heartworm antigen test, which identifies an antigen produced by the adult female heartworm. False negatives occur in dogs with early infections (before the appearance of mature worms), in light infections with fewer than five adult worms and in infections in which only males are present. False positives are rare. Another important heartworm test is the microfilarial concentration test, in which parasites in a sample of blood are identified under the microscope. Although a positive test definitely indicates heartworms, a negative test does not rule out the diagnosis because typically 10 to 25 percent of infected dogs do not have microfilariae circulating in the peripheral blood. Dogs with a negative microfilarial concentration test who do have heartworms are said to be suffering from an occult infection. There are a number of explanations for occult infection. One is that the dog is receiving a heartworm preventive. Preventives kill microfilaria but not adult worms. Thus these dogs will have a positive heartworm antigen test and a negative microfilarial concentration test. Also, a dog could be infected with adult heartworms of just one sex, which means no reproduction is taking place. There is yet another type of microfilaria that can be present in dogs tested for heartworms. It is called Dipetalonema. It is a harmless worm living under the skin. Its importance lies in the fact that its microfilaria may be mistaken for those of heartworm. This can be differentiated from heartworm microfilaria by careful examination under a microscope. A chest X-ray is the best test for determining the severity of the infection. Dogs with a heavy burden of worms in the pulmonary artery have X-rays that show enlargement of the right ventricle and/or pulmonary arteries. An ECG may show right ventricular enlargement and cardiac arrhythmias. An echocardiogram may show worms in the pulmonary artery or the right ventricle. In dogs with vena cava syndrome, heartworms can be seen in the vena cava. Blood and urine samples are obtained to check for anemia and assess kidney and liver function.

Anemia and Clotting Disorders

Anemia is defined as a deficiency of red blood cells (erythrocytes) in the circulatory system. Adult dogs are anemic when the concentration of red cells in whole blood is less than 37 percent by volume. The normal range is 39 to 60 percent. Red cells are produced by the bone marrow and have an average life span of 110 to 120 days. Old red cells are trapped by the spleen and removed from the circulation. The iron they contain is recycled to make new erythrocytes. The purpose of red blood cells is to carry oxygen. Thus, the symptoms of anemia are caused by insufficient oxygen in the organs and muscles. Signs include lack of appetite, lethargy and weakness. The mucous membranes of the gums and tongue become pale pink to white. In dogs with severe anemia, the pulse and respiratory rate are rapid and the dog may collapse with exertion. A heart murmur may be heard. Anemia can be caused by blood loss, hemolysis, or inadequate red blood cell production.

Blood-Loss Anemia

In adult dogs the most common causes of blood loss are trauma, slow gastrointestinal bleeding associated with stomach and duodenal ulcers, parasites and tumors in the gasrointestinal tract. Chronic blood loss also occurs through the urinary system. Hookworms and fleas are common causes of chronic blood loss in puppies.

Hemolytic Anemias

Hemolysis is an acceleraton in the normal process of red blood cell breakdown. Red blood cells break down to form bile and hemoglobin. With severe hemolysis, these breakdown products accumulate in the body. Accordingly, in a dog experiencing an acute hemolytic crisis you would expect to see juandice and hemoglobinuria (passing dark-brown urine that contains hemoglobin). In addition, the dog appears weak and pale and has a rapid pulse. The spleen, liver and lymph nodes may be enlarged. Causes of hemolysis include immune-mediated hemolytic anemia, congenital hemolytic anemia, infectious diseases (such as canine babesiosis and leptospirosis), drug reactions to medications such as actaminophen and poisonous snake bites. A number of bacteria produce toxins that destroy red blood cells, so hemolysis can also occur with severe infections. Neonatal isoerythrolysis is a hemolytic disease of newborn puppies.

Immune-Mediated Hemolytic Anemia

This is the most common cause of hemolysis in adult dogs. Red blood cell destruction is caused by auto-antibodies that attack antigens present on the surface of the cells or by antigens from medications or organisms attached to the red blood cell walls. The weakened cells are trapped in the spleen and destroyed. Poodles, Old English Sheepdogs, Irish Setter and Cocker Spaniels are predisposed to immune-mediated hemolytic anemia, but all breeds are susceptible. Affected dogs are usually between 2 and 8 years of age; females out number males four to one. Most cases of immune-mediated hemolytic anemia are idiopathic. That is, the reason why the auto-antibodies developed in that particular dog is unknown. In some cases there is a history of recent drug therapy. An immune-mediated hemolytic anemia also occurs with systemic lupus erythematosus. The diagnosis is made by microscopic examination of blood smears, looking for specific changes in the appearance of the erythrocytes and other blood elements; and by serologic blood tests.

Congenital Hemolytic Anemia

Several inherited abnormalities in the structure of red blood cells can result in their premature destruction. Phosphofructokinase deficiency is an autosomal recessive trait that occurs in English Springer Spaniels and Cocker Spaniels. A deficiency of this enzyme results in changes in the pH of red blood cells, causing the cells to periodically fragment and produce bouts of hemoglobinuria. There is no effective treatment. Pyruvate kinase deficiency is another red blood cell enzyme deficiency caused by an autosomal recessive gene. This disease is recognized in several breeds, including Basenji's, Beagles and West Highland White Terriers. Puppies usually develop the hemolytic anemia at 2 to 12 months of age. Death by age 3 is the usual outcome.

Inadequate Red Blood Cell Production

When the metabolic activity of the bone marrow is depressed, new red blood cells are not manufactured as fast as old ones are destroyed. This results in an anemia due to inadequate red blood cell production. A common cause of bone marrow depression is chronic illness, especially associated with kidney and liver disease. Iron, trace minerals, vitamins and fatty acids are all incorporated into red blood cells. Thus a deficiency of one or more of these nutrients could slow down or stop cell production. Iron deficiency is an exception. It occurs when iron is lost from the body faster than it can be replaced through the diet. The two situations in which this is most likely to happen are chronic gastrointestinal bleeding and a heavy infestation of blood-sucking insects (such as fleas, ticks, or lice). red blood cell production can be depressed by certain drugs. Estrogen is an important cause of bone marrow depression. This includes estrogens given for medical purposes as well as those produced by testicular and ovarian tumors. Other drugs that depress the bone marrow include chemotherapy agents, chloramphenicol, butazolidin, thiacetarsamide, quinidine and trimethoprimsulfadiazine. Primary and metastatic cancer can invade the bone marrow and crowd out normal cells, also depressing red blood cell production. The diagnosis of inadequate red cell production is made by bone marrow biopsy.

Clotting Disorders

Clotting disorders are caused by an absence of one of the coagulation factors needed to complete the clotting sequence. Severe deficiencies are associated with spontaneous bleeding. Blood in the urine or stools may be associated with a spontaneous bleeding disorder.

Von Willebrand's Disease

Von Willebrand's disease (vWD) is the most common inherited bleeding disorder in dogs. It has been described in more than 50 breeds. Both males and females can transmit and express the genetic trait. The disease is inherited as an autosomal dominant gene with variable expression. That is the severity of the bleeding is related to the degree to which the gene is expressed. The bleeding is caused by a deficiency of a plasma protein called the von Willebrand factor, which is critical for normal platelet function in the early stages of clotting. In most cases the bleeding in vWD is mild or inapparent, and lessens with age. Severe problems include prolonged nosebleeds, bleeding beneath the skin and into the muscles and blood in the stool and urine. There is often a history of bleeding from the gums following tooth eruptions and oozing from wounds following tail docking and dewclaw removal. Breeds at risk for vWD in which bleeding is likely to be mild include the Doberman Pinscher, Golden Retriever, Standard Poodle, Pembroke Welsh Corgi, Manchester Terrier, Miniature Schnauzer, Akita and others. Breeds in which bleeding is likely to be more severe include the Scottish Terrier, Shetland Sheepdog, German Shorthaired Pointer and Chesapeake Bay Retriever. Hypothyroidism is common in dogs with vWD and may contribute to the bleeding risk. The diagnosis is made by specific blood tests, including a bleeding time. In this test, a small cut is made and the amount of time it takes for bleeding to stop on its own is measured. From a nail cut too short, two to six minutes is normal, while from a cut on the gums, two to four minutes is normal. A quantitative test for von Willebrand's disease involves measuring the vWD antigen. Dogs with vWD antigen levels below the normal range are at risk for expressing and/or carrying the trait.

Hemophilia

This is a sex-linked recessive trait that occurs only in males who inherit a maternal X chromosome carrying a defective gene. Females always inherit two X chromosomes, at least one of which usually contains a normal dominant gene. Thus females can carry the trait but do not develop the disease - the exception being a female who inherits two recessive genes: one from a hemophiliac father and the other from a mother who is either a hemophiliac or a carrier. This is extremely rare. Hemophilia produces bleeding into the chest and abdominal cavities, muscles and subcutaneous tissues. Bleeding into the joints is common. Hemophilia A (the most common type) is a deficiency of coagulation factor VIII. Hemophilia B is a deficiency of factor IX. Hemophilia occurs in all breeds, with a predisposition amoung German Shepherd Dogs, Airedale Terriers, Bichons Frises. Other coagulation deficiencies involve factors VII, X, XI and prothrombin. These deficiencies are inherited as single-factor autosomal traits and affect males and females alike. They are less common than hemophilia. Affected breeds include the Boxer, English and American Cocker Spaniel, English Springer Spaniel, Beagle and Kerry Blue Terrier. The diagnosis of a coagulation factor deficiency is based on a number of clotting tests, plus an analysis for the specific factor that is deficient.

Disseminated Intravascular Coagulation

This is an acquired bleeding disorder triggered by shock and infection, certain tumors (particularly hemangiosarcoms, osteosarcomas and cancers of the prostate and mammary glands), and severe injuries such as crush wounds and burns. Disseminated intravascular coagulation (DIC) is characterized by intravascular clotting throughout the entire capillary circulation, followed by spontaneous bleeding when all the clotting factors have been consumed. The bleeding associated with DIC involves the nose, mouth, gastrointestinal tract, and body cavities. Dogs with DIC are extremely ill and often die. Another acquired bleeding disorder is caused by vitamin K deficiency.