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Congestive Heart Failure
How common is heart disease in dogs?
About 10% of all dogs have heart disease. Most smaller dogs have a condition called Congestive Heart Failure (CHF). Most larger breeds have a heart condition called Dilated Cardiomyopathy (DCM).
Most importantly, the incidence of heart disease increases dramatically with age. The incidence of heart disease increases to more than 60% in aged dogs. This is particularly the case in dogs with valvular heart disease:
- About 10% of dogs between the ages of 5 and 8 years are affected3
- 20-25% of dogs between the ages of 9 and 12 years are affected
- 30-35% of dogs more than 13 years are affected
- 75% of dogs over 16 years are affected
What Is Valve Disease?
Known by various names, Atrioventricular Valvular Insufficiency (AVVI), mitral valve disease, or Congestive Heart Failure (CHF) it is the most common form of heart disease in the dog. Three quarters (75%) of the cases of canine heart disease in North America are caused by chronic valve disease.
As the name suggests, this disease affects one or more of the heart valves. Heart valves normally form a perfect seal when closed. However, in valve disease one or more of these valves "leak," allowing blood to be pumped backwards. This backward flow creates a noise, called a murmur, which your vet can hear with a stethoscope. Most dogs (70%) with mild mitral valve abnormalities will never develop CHF. In these dogs, the condition can be considered benign and treatment will not alter clinical outcome.
Normally the heart valves snap closed with each heartbeat making a "thud" sound and that is the sound we hear with the stethoscope. With age or disease, the the heart valves do not completely close with the heart beat and we hear a "woosh" sound from the valve vibrating. That sound is called a heart murmur. Murmurs indicate that not all of the blood is getting pumped out of the heart with each beat. Mild heart murmurs do not cause any problems. Severe murmurs can mean CHF.
How Will Heart Disease Affect My Dog?
Most forms of heart disease will, unfortunately, eventually result in congestive heart failure or CHF. Congestive heart failure occurs when the heart, weakened by disease, fails to pump enough blood to meet the body's needs. Because a large amount of blood cannot get pumped out of the heart, fluid accumulates within the air spaces in the lungs resulting in increased breathing rate and eventually resulting in coughing.
If your dog has been diagnosed with heart disease, don't panic. With early diagnosis and appropriate treatment and management, you increase your dog's opportunity to live a more normal life.
How is a heart problem diagnosed?
It is important for you and your dog to make regular visits to the veterinarian. Early diagnosis and treatment will ensure your dog leads a happier, healthier, and longer life. Your veterinarian will follow a series of key steps and use some of the latest diagnostic tools to distinguish heart disease from respiratory problems.
1. Clinical History - The veterinarian will need to know the age, breed, and medical history of your
dog. He/she will evaluate the onset and type of cough and may ask about:
Changes in attitude, behavior, and activity level
- Changes in attitude, behavior, and activity level
- Changes in breathing rate
- Coughing, especially at rest during the night
- Changes in appetite and weight
- Sleeping habits
- Previous evidence of heart disease
- Previous treatment history
Measure the Resting Respiratory Rate (RRR) at home. This is a very sensitive indicator of heart disease resulting in fluid accumulation within the lungs (Congestive Heart Failure)
- Observe and record the number of breaths the dog takes over 60 seconds when the dog is quiet, preferably sleeping. Do this once daily for 7 days to get a baseline number for the RRR. Normal RRR is from 12-20 breaths per minute.
- If the RRR ever goes above 35 breaths per minute, have the dog evaluated immediately. If the RRR goes 25% to 50% over the normal RRR, then have the dog checked. For
example if the dog has a RRR of 20 breaths per minute and then it goes to 25 or 30 breaths
per minute, have the dog checked.
2. Physical Examination - a thorough physical examination will provide your veterinarian with clues as to whether your dog has any heart-related problems. He/she will evaluate:
- Weight and body condition
- Breathing rates
- Heart rates
- Pulse rates
- Skin or tissue abnormalities
- Abdominal shape
3. Listening to your dog's heart and lungs - A stethoscope may allow your veterinarian to determine if a heart murmur is present. (Appreciate that not all murmurs are easily heard.) Also, the heart rate and rhythm can be assessed with a stethoscope to determine if there is an irregular heartbeat. He/she can listen to the lungs to detect abnormal sounds.
4. X-rays - Technically known as radiographs, an x-ray can help the veterinarian evaluate the size and shape of the heart and assess the severity of your dog's heart disease.
NORMAL DOG HEART
SEVERELY ENLARGED HEART CHF
What Is Standard Treatment for CHF?
The American College of Veterinary Internal Medicine (ACVIM) guidelines encourage veterinarians to use three different drugs to treat CHF in dogs.
The recommended standard treatment for dogs with CHF should include:
- Furosemide (Lasix, Salix) A diuretic medicine that helps to dry out the wet lungs
- Pimobendan (VETMEDIN) A medicine that helps to strengthen the heart contractions and to open up the constricted blood vessels away from the heart allowing more blood to flow out of the heart with each heart beat.
- Angiotensin Converting Enzyme (ACE) inhibitor (Enalapril, Benazepril) A medicine that prevents the blood vessels from constricting. If the blood vessels in the tissues remain open, then the heart has to work less to pump blood to the distant organs. Another advantage of ACE inhibitors is to allow increased kidney blood flow resulting in better filtration of the blood. If the blood vessels to the kidney remain constricted, then the kidney cannot filter toxic waste from the body. ACE inhibitors also promote sodium excretion through the urine to lower the blood pressure and to prevent fluid accumulation in the lungs.
Caring for Your Dog with CHF
Visiting your veterinarian It is likely that your dog will be put on long-term medication after being diagnosed with congestive heart failure, so your visits to the veterinarian may need to be more frequent at first. However, once your dog’s condition has stabilized with treatment, you can expect to resume a more regular and potentially less frequent visit schedule.
The objective of successful treatment is to make your dog feel better and live longer, at the same time as minimizing unexpected problems and emergency visits.
Diet and Exercise
Your veterinarian may recommend dog food that is nutritionally well-balanced and suitable for a dog with a heart condition. Some degree of sodium (salt) restriction may be recommended for some patients.
Ask your veterinarian about treats and “people food,” such as cheese and meat, as many foods will not be suitable for a dog in heart failure. Avoiding high sodium (salty) foods is often recommended.
Exercise is important, but it’s recommended that you consult your veterinarian about the type, level, and frequency of exercise for your dog. If your dog collapses or seems weak during activity, you should consult your veterinarian immediately.