Minimizing Congestive Heart Failure in Dogs: Methods for Preventing and Management
Heart disease in dogs is almost as common as it is in humans. Cardiac diseases in canines are an extensively studied phenomenon all over the world but meager information has been reported in India. The recognition of canine cardiac diseases has been delayed, and ignored on account of lack of awareness and knowledge by the owner and inadequate diagnostic facility in our country (Devi et al., 2009). Despite these numbers, many people are unaware that their dog may be at risk of heart disease. It is important that every dog considered vulnerable to cardiac diseases should be examined for cardiac function during routine examination.
A delay in diagnosis and treatment could result in a grave prognosis or life threatening condition. Many a times the condition is detected too late until pronounced signs appear (Martin et al., 2009). The substantial involvement of heart has provoked numerous investigations leading to advancements in medical and surgical management of cardiovascular disorders. Presently access to echocardiographic facility in veterinary practice has revolutionized the field of cardiology by aiding the diagnosis and management of cardiac diseases in dogs.
A heart attack, or “myocardial infarction,” happens when blood is blocked from reaching the heart muscle (myocardium). Deprived of oxygen and nutrients, the heart muscle dies and the affected heart chamber can no longer effectively pump blood through the body. Canine heart attacks have been seen in all breeds and are very rare. Increased risk for heart attack can be seen accompanying heart disease, congenital heart abnormalities, and genetic predisposition. Heart attacks require emergency medical attention and can result in sudden death. Canine heart attacks have been seen in all breeds and are very rare. If you notice symptoms of a heart attack in your dog, keep calm and contact a veterinarian immediately.
Congestive heart failure (CHF) is fairly common in dogs. Approximately 10% of all dogs, and 75% of senior dogs, have some form of heart disease. CHF itself is not a disease: it is a condition that is a result of heart disease. Congestive heart failure in dogs occurs when the heart is unable to pump an adequate amount of blood to the body, thus causing an increase in pressure and fluid that eventually leaks into the lungs and, less frequently, other major organs.
When fluid accumulates in or around a dog’s lungs, it prohibits the lungs from expanding normally and prevents oxygen from moving into the bloodstream properly. This can cause a variety of symptoms and health issues.
Symptoms of Heart Attack in Dogs
There is little warning for a heart attack event. Collapse may be the first symptom observed. Symptoms associated with canine heart attack can include:
- Slight fever (over 103° Fahrenheit/39.4° Celsius)
- Vomiting
- Panting/abnormal breathing
- Increased heart rate (over 100 beats per minute for large breeds) (over 140 beats per minute for small breeds)
- Lethargy
- Head tilt
- Confusion/Anxiety
- Immobility
- Rigidity
- Seizure
- Collapse
- Sudden death
Causes of Heart Attack in Dogs
Causes of heart attack in dogs include:
- Tumor: Tumor masses growing on or around the heart vasculature can block blood flow to the heart muscle.
- Hypothyroidism: Thyroid gland does not produce thyroxine hormone – responsible for converting food to fuel for the body.
- Nephrotic Syndrome: Kidney damage results in loss of protein involved in preventing blood clot formation. Blood clots are one cause of canine heart attack.
- Bacterial infection: Infection in the body can lead to inflammation and blockage of blood flow to the heart muscle.
- Vasculitis: Blood vessel inflammation as a result of infection, immune-mediated disease, or other injury to endothelial linings. Results in narrowed vasculature.
- Atherosclerosis: Plaque builds up in the arteries, restricting blood flow or rupturing arteries. Rare in dogs but has been reported in some breeds.
- Coronary artery disease: Extremely rare in dogs. Occurs only with severe hypothyroidism and associated high serum cholesterol levels.
Several factors can increase a dog’s risk of congestive heart failure.
These include:
Age – The incidence of CHF is higher in middle-aged to older dogs. Chronic valve disease (CVD) is the most common cause of congestive heart failure in dogs and affects more than 60% of senior dogs.
Size – Large dog breeds have higher risks for dilated cardiomyopathy, which is a leading cause of heart failure in these breeds. Some of the most common breeds affected by CHF are Labrador Retrievers, Golden Retrievers, and Doberman Pinschers.
Breed – Mitral valve degeneration (MVD) is a common cause of heart failure in small dog breeds. However, certain small breeds, such as the Toy Poodle, Shih Tzu, and Chihuahua have higher risks of being affected. Among the small dog breeds, it’s the Cavalier King Charles Spaniel that is most at risk for MVD.
Boxers are also prone to hereditary conditions affecting the heart (Boxer cardiomyopathy) that can lead to heart failure.
Heartworm disease – Untreated heartworm infections can increase a dog’s risk for CHF. As the number of adult heartworms increases, they can clog the heart and its major blood vessels. The worms can also interfere with the actions/functions of the heart valves.
Heart murmurs – When a defective heart valve leaks blood back into one of the heart’s chambers, it can cause a heart murmur, a condition that is usually an incidental finding during a routine medical exam. Most heart murmurs don’t cause any problems, but they can worsen with time, and can eventually lead to heart failure.
Diet – Nutrition-related factors, such as obesity, certain nutritional deficiencies, and a high-salt diet, can increase a dog’s risk of developing heart problems.
When your dog is overweight or obese, his heart will need to work harder so adequate blood can be circulated throughout the body.
Specific nutritional deficiencies, such as a lack of taurine ( a type of amino acid), can increase a dog’s risk of heart enlargement.
Dental disease – When your dog has a gum or tooth infection, bacteria from the mouth can enter the blood circulation and reach major organs of the body, such as the heart, and cause serious bacterial infections. Scientific studies have been able to demonstrate a strong association between tooth and gum disease and heart valve inflammation.
In dogs, there are two main types of CHF:
- Right-sided congestive heart failure (RS-CHF).This occurs when a heart contraction causes some blood to leak into the right atrium from the right ventricle through the tricuspid valve rather than being pushed through the lungs and becoming oxygenated. As a result, the main circulation system becomes congested with backed up blood, and fluid accumulates in the abdomen, interfering with proper organ function. Excess fluid might also build up in the limbs and cause swelling known as peripheral edema.
- Left-sided congestive heart failure (LS-CHF).The most common type of CHF in dogs, this occurs when blood from the left ventricle leaks back into the left atrium through the mitral valve rather than getting pumped into the body’s systemic circulation when the heart contracts. It is a state of diminished cardiac function as a result causes volume or pressure overload to the left side of the heart. As a result, fluid leaks into the tissue of the lungs, causing swelling known as pulmonary edema, which leads to coughing and difficulty breathing.
CHF in dogs is broken down into four stages. Stages one and two present few symptoms, and owners may be unaware something is wrong until the condition has progressed to a later stage.
- Stage 1:The dog’s heart is beginning to deteriorate. Visible signs and symptoms have not yet presented themselves.
- Stage 2: Symptoms like panting, shortness of breath, and fatigue, especially after exercising, begin to present themselves.
- Stage 3:Fatigue and shortness of breath occur more frequently, even on short walks. Coughing and wheezing may begin. Since the heart is not pumping efficiently, an accumulation of fluid in the chest causes breathing difficulties.
- Stage 4:CHF is in its final stage. Breathing becomes difficult even when at rest. Fluid can accumulate in various parts of the body, causing swollen legs or belly, making it difficult to walk. It can even cause vomiting.
Stages of Congestive Heart Failure
The risk and progression of CHF in dogs is classified by stages similar to the way it is categorized for humans with CHF. The stages run from an initial risk for developing CHF but not showing any symptoms (Stage A) to severe symptoms (Stage D).
- Stage A: Dogs with a higher risk for developing CHF but currently show no symptoms or structural changes to the heart. Dogs with a genetic risk include small breeds such as Miniature Poodles, Cocker Spaniels, Terrier breeds, and some larger dogs such as Great Danes or Dobermans.
- Stage B: Dogs with a heart murmur (a “whooshing/swishing” sound) that a vet can hear but does not show any symptoms. A murmur indicates turbulent blood flow within the heart
- Stage B2: Dogs that show a structural change on an X-ray/radiograph or echocardiogram (a specialized ultrasound to diagnose the heart) but are without symptoms.
- Stage C: In this stage, symptoms of heart disease are present. Dogs in this stage will have current or historic clinical signs of congestive heart failure, but still respond positively to medications and treatment.
- Stage D: This stage is referred to as “end-stage” disease. In this stage, a dog will typically have severe symptoms of disease that unfortunately no longer respond to medications or other treatments.
Diagnosis of Heart Attack in Dogs
If you notice symptoms of a heart attack in your pet, keep calm and carefully wrap the pet in a blanket to calm him. Do not attempt CPR unless you have been professionally trained and know it is necessary. CPR can do more harm than good if it is not needed. Do not attempt to feed or give water in case of vomiting/asphyxiation. Keep young children away from the pet as pain and panic can cause aggressive behavior.
Calmly place your palm on the left side of the chest to feel the heart rate. Count the number of beats in 15 seconds and multiply your answer by 4. This gives you the number of beats per minute. Normal heart rate in dogs will be around 60-140 beats per minute depending on their size. Transport your pet to the veterinarian as soon as you can.
If your pet collapses, keep calm and carefully wrap her in a blanket and transport her to the veterinary clinic. Try to keep the events leading up to the collapse in your mind so you can report them to the veterinarian.
The veterinarian will collect any history as to what led up to the symptoms or collapse event. The vet will listen to the heart for any murmur, irregular pulse, or arrhythmia. Laboratory diagnostics can reveal valuable information as to cardiac function and possible causes of symptoms you are observing.
- Electrocardiography (EKG): Determines cardiac electrical impulses and measures arrhythmias.
- Complete Blood Cell Count (CBC): Determines red and white blood cell count, can detect possible infection.
- Biochemistry: Examines kidney and liver function.
- Urinalysis: Examines kidney and metabolic function.
- Thyroid: Examines thyroid gland function.
- Echocardiography: Detects fluid or masses around the heart, heart valve function, heart muscle and pericardial health.
- Chest X-ray: Determines size of heart, fluid around heart, possible masses.
A Holter monitor or ambulatory EKG is useful to monitor heart health at home. Electrodes are taped onto the chest and the device is strapped on the back for 24 hours. The heart rhythms are recorded and times of rest versus times of exercise or stress are reported by the owner. The recording is analyzed for abnormal heart activity.
Treatment of Heart Attack in Dogs
Initial treatment may involve resuscitation and supportive care, depending on seriousness of the event. The initial goal is to regain normal heart activity. Medications may be used to thin the blood for ease of circulation. Hospitalization is often necessary to continue heart monitoring until the veterinary staff is certain the pet is stable.
A variety of medications are available for cardiac abnormalities depending on the identified cause. Pacemaker implants are more widely available for canines predisposed to heart problems. Surgery may be required to remove any mass that may be obstructing blood flow to or from the heart. Thyroid hormone replacement medications are common and available. Various diets and medications may provide preventive/supportive care for renal disease if damage is not severe. Antibiotics may prevent further damage to vessels and heart lining resulting from infection or inflammation. Anti-arrhythmic medications can correct arrhythmias.
Once the pet has become stabilized, potential of recurrence is based on cause of the problem and severity of the myocardial infarction. Surgery and medications can extend the life of the pet for many years when the issue is diagnosed early and treated responsibly. Medications may need to be administered over the remaining life of the pet. In the case of collapse, your pet may need to remain in the hospital overnight or longer for monitoring.
Recovery of Heart Attack in Dogs
The life of your pet after a heart attack will depend on the severity of the attack and its cause. Lifelong treatment may be required in the case of hypothyroidism, renal or heart disease. Regular heart monitoring in the veterinary clinic or with an ambulatory EKG recorder may be necessary to ensure stabilization over the first few weeks or months, possibly a few times per year for younger pets.
Activity restriction may be necessary for the first month while the pet stabilizes. Owners may want to become familiar with normal heart and breathing rate of their pet so rates can be taken after various times of high activity or stress. Change of diet or dietary supplements may be suggested by the veterinarian depending on the cause and severity of the event.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
Reference-On Request.
