Let’s talk about common heart diseases in dogs. First of all, we should know heart diseases could be congenital or acquired. There are 2 common acquired heart diseases in dogs.
One is failure of the heart muscles caused by genetic factor and usually occurs in large breeds of dogs (over 20 kgs) called dilated cardiomyopathy (DCM), and the other one is the abnormality of the mitral valves caused by degeneration and common be found in small breeds of dogs called myxomatous mitral valve disease (MMVD) or degenerative mitral valve disease (DMVD).
DCM is a degeneration of the heart muscle and this degeneration result in the muscle becomes thinner and more weakness. Failure of the heart muscles unable to pump enough blood to the organ and the pressure of the blood inside the heart causes these thin walls to stretch leading to a much larger heart. It is common in certain large breeds of dogs, include Doberman Pinschers, Great Danes, Irish Wolfhounds, Boxer, and Saint Bernards. Occasionally, some medium-sized breeds, such as Cocker Spaniels and English Springer Spaniels are also affected.
DCM may have a sudden onset of clinical signs, however, the disease have actually been developing slowly and subtly. When it develops into congestive heart failure, rapid heavy breathing, a blue tongue, or collapse maybe the first signs. Annual checkups with your veterinarian may lead to a diagnosis of heart problem before clinical signs are present. There are several drugs used to treat the symptoms of DCM. Initial stabilization depends upon the use of oxygen, diuretics and drugs which improve the heart muscle strength. Many dogs with DCM have arrhythmias, therefore, some antiarrhythmic drugs may be added in cautiously.
DCM is a serious disease that must be accurately diagnosed and aggressively treated. Doberman Pinschers have been shown to live as little as 3 months once diagnosed. Other dogs have been known to live between 6 to 24 months if they respond well to treatments. Dogs that have developed clinical signs of heart failure have a worse prognosis than those that are put onto cardiac medication in the early stages of the disease.
MMVD should be the most common heart disease in dogs in Hong Kong. Because Hong Kong people usually have small breeds of dogs, and MMVD is the most common heart disease in small breeds of dogs. The most susceptible breeds are Cavalier King Charles Spaniels, Poodles, Schnauzers, and Chihuahua. The mitral valve is located on the left side of the heart between the left atrium and the left ventricle. It closes completely and prevents blood flowing back to the left atrium when the left ventricle contracts. MMVD occurs when the mitral valve becomes thickened. The thickened valve results in incomplete closure of the valve allowing blood to leak backward into the left atrium. This backward blood flow is called mitral regurgitation. The leak worsens over time causing increased pressure within the heart and also causing heart to enlarge. Eventually, the heart will go into the congestive heart failure.
Most dogs with mild to moderate MMVD may not show any signs of disease. Regular checkups with the vet can pick up the disease in the early stage. Coughing is a more common sign seen the dogs with MMVD. Patients can cough for two reasons. Enlargement of the heart compressing on the airway or fluid accumulation in the lungs from congestive heart failure. It has been shown that early starting the medication in moderate to severe MMVD can delay the time to development of congestive heart failure by a median time frame of 15 months.
If your pets are in an emergency or if you have general inquiries, please do not hesitate to contact Veterinary Emergency Centre.
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