Heart disease happens to dogs of all ages, breeds and levels of physical fitness. In younger animals, it is commonly caused by congenital abnormalities. In older animals, heart disease is normally a result of a weakened or overworked valve or chamber that alters the flow of blood. Cardiac disease is incurable and progressive, and dog owners need to learn the signs and symptoms their animals will show to better provide the veterinary treatment necessary to give a better quality of life.
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Physical Signs
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Dogs with heart disease will usually show either a higher or lower heart rate than normal. Small dogs typically have heart rates ranging from 120 to 160 beats per minute; the hearts of dogs weighing more than 30 pounds will beat from 60 to 120 beats per minute. A heart rate outside the normal range, either higher or lower, signifies a heart problem to a veterinarian. Vets may also hear arrhythmias during auscultation of the affected animal.
Most animals will suffer from either hypertension (high blood pressure) or hypotension (low blood pressure) because of cardiac disease. As the heart attempts to push blood through the vascular system, it will overcompensate for its insufficiencies by beating faster and raising the pressure inside the blood vessels. Low blood pressure occurs as the disease progresses and the organ begins to fail.
Systemic hypertension will cause the blood flowing in the vessels of the dog̵7;s lungs to leak into lung tissue causing pulmonary edema. The animal will begin to cough in an effort to expel this extra fluid, usually after exercise or sleeping. As the heart disease worsens, the dog may accumulate fluid in its abdomen and limbs.
When the dog̵7;s heart is unable to perfuse body tissues with blood in a normal manner, the animal̵7;s mucous membranes will appear pale or gray in color instead of pink. A quick test to assess circulation̵1;pressing a finger to the animal̵7;s gums to see how long it takes for the pink color to return̵1;is called capillary refill time (CRT). Normal CRT is around two seconds. Any time over that is a sign of heart disorders.
Behavioral Indications
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Dogs with heart disease usually demonstrate signs of lethargy and fatigue. They may not want to eat or drink and may even become nauseous. They may begin panting and show exercise intolerance, an inability to continue with their normal physical routine. After physical exertion, some dogs with heart disease will faint due to insufficient blood flow to the brain.
Terminal Signs
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As the cardiac disease progresses, the dog̵7;s heart will begin to fail and the heart rate will slow down. Many dogs will lose their ability to get up and down or will do so with decreasing strength. They may become ataxic, meaning they lose control of their limbs. As the lungs become increasingly compromised, the dog will begin to pant and may start to vomit fluid. Eventually, the affected animal will become comatose and die.
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