chf

Congestive Heart Failure (CHF) is a complex and serious condition leading to the build-up of fluids in and around the lungs and other organs due to inefficient heart function. CHF is a progressive, incurable disease resulting in excessive retention of water and salt causing fluid build-up in the lungs. and has many causes. The major underlying cause being degeneration of the heart valves. It is important to remember that a degeneration of heart valves is a common aging change in small breed dogs and that the presence of a heart murmur does not necessarily indicate heart failure. CHF occurs commonly in small dogs, who are especially susceptible to heart murmurs and therefore at greater risk of suffering problems due to a weakening heart in old age.

"There are three main signs to be aware of in dogs with congestive heart failure. These are exercise intolerance, labored breathing and coughing. "It is important to provide your dog with a yearly check-up and allow your veterinarian to follow up on any abnormal findings." A physical exam and a cardiovascular exam including chest radiographs, an electrocardiogram and in many cases an echocardiogram are usually performed.

One of the first symptoms of CHF is a moist, sometimes gagging cough in an exerted or excited pet. This may be accompanied by exercise intolerance, a general lack of energy, and sometimes fainting spells. The CHF cough can easily be mistaken for kennel cough. Only a vet can determine if your pet has CHF.

Treatments
1.Diet - a low sodium diet to restrict sodium intake.
If your dog has or is at risk for CHF, one of the best things you can do at home is to reduce and carefully monitor his sodium (salt) intake. Sodium causes water retention, the one thing your CHF pet doesn't need. Even if your dog is healthy, keep him that way longer by putting him on a strict low-sodium diet now and stop feeding table scraps -- human food is loaded with salt (which isn't good for us either). If your dog turns his nose up, substitute a little low-sodium salt or add garlic powder (NOT garlic salt) to enhance flavour.

Helpful hint: if your dog has regular coughing fits while eating or (more commonly) drinking, try placing the food and water dishes up on a platform to raise them to your pet's chest level. Not having to bend down so far will reduce the stress on his heart and lungs, which should ease the cough reflex.

2.Diuretics - these are drugs that signal the kidneys to excrete excess sodium and water.
Your vet may prescribe a diuretic to help shift fluids from the body, and/or heart medicine to help the heart pump blood more efficiently, further aiding the removal of fluids and enhancing overall health.

Enacard (also known as Vasotec, generic name enalapril) is currently one of the most popular heart medications for dogs with CHF. It is often prescribed alongside a diuretic like furosemide. Kidney parameters (BUN and Creatinine) should be measured prior to enalapril use, again 3-7 days after
enalapril therapy has started, and periodically thereafter.

Kidney function should also be rechecked after any dose change in the heart failure patient. Enacard's benefits are proven, but it does come with the risk of inducing kidney (renal) dysfunction. Therefore, any dog placed on a diuretic and/or Enacard should have an initial blood test to check kidney function, another blood test 7-10 days after starting the drug(s), and thereafter on a regular basis.

If your dog is put on Enacard (enalapril) or a diuretic, demand regular blood tests if your vet isn't already doing them. Senior dogs (8 years +) should have regular blood tests regardless of their health as preventive medicine. The sooner CRF is caught, the more can be done to improve your pet's quality of life and longevity. Enalapril is less effective in the presence of aspirin or other NSAIDs (Non-Steroidal Anti-Inflammatory Drugs).

3.Dilators - these drugs either dilate arteries (to decrease stress on the heart), dilate veins (to decrease pressure on backside of heart and relieve congestion), or both.

4.Digoxin (Digitalis) - these drugs make the heart beat stronger, slow the heart, and reestablish normal cardiovascular responses.

Canine Congestive Heart Failure

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Heart Failure Therapy

Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com

Long-Term Therapy for Heart Failure
When the heart is not able to pump out the volume of blood it receives (backward failure) or cannot pump out enough blood to supply oxygen to the body (forward failure), the goal is to avoid or resolve a life-threatening crisis. Once the short-term disaster is resolved, we look to a more long-term therapy plan.

The Basics of Short-Term Heart Failure
In the short term, the body has an assortment of mechanisms to preserve circulation to the heart and brain and keep blood pressure up. The problem is that these mechanisms evolved for protection against blood pressure drop due to bleeding (as in predator attack). Protection against heart failure is an added benefit in the short term but in the long term problems arise.

So let’s say blood pressure drops. It could be because a predator has taken a bite out of a large blood vessel and there is bleeding or more relevant to the topic of this discussion, it could be because the heart is not moving an adequate quantity of blood forward. Either way the tissues of the body need more blood supply and they need it quickly. What does the body do?

Neurologic reflexes are activated that cause the heart to pump faster and stronger to move the maximum blood with each contraction.

Antidiuretic hormone and aldosterone (an adrenal hormone) are released telling the kidney to hang on to every last sodium atom it sees. Where there is sodium, there is water and water (blood is mostly water) is the medium through which supplies reach our tissues and wastes are removed from our tissues. If we are going to have adequate blood, we need adequate water and that means hoard sodium.
A hormone system called the renin-angiotensin system kicks on to produce a material called Angiotensin II. Angiotensin II is one of the strongest vasoconstrictors known to science. It closes off vessels supplying non-essential areas preserving circulation for the heart and brain, which must be kept perfused at all costs.

So, in short, our heart works harder, our vessels close off, and we retain salt. This is all wonderful but if the heart is weak, it cannot handle the extra blood volume brought on by retaining salt, nor can it push blood through constricted vessels or continue pumping faster and harder all the time.

Long-Term Heart Failure Management
Managing the failing heart is all about creating a balance for what a sick heart can handle and lifting the burden created by the protective mechanisms of the crisis. Our patient should be comfortable and able to perform modest exercise. We want to minimize discomfort due to coughing, fluid build-up, or collapse.

Diuretics
A diuretic is a drug that increases urine production. Diuretics are life-saving in a heart failure crisis where the lungs are filling with fluid because the heart cannot pump blood in quantities large enough to prevent fluid build-up. The dose needed for long term comfort is highly individual and may change depending on the stage of disease. Furosemide is almost always the first diuretic used as it is one of the most powerful. It is often used in combination with an ACE inhibitor for long term therapy.

ACE Inhibitors
ACE stands for angiotensin converting enzyme. We briefly mentioned the renin-angiotensin system above. Angiotensinogen is an inactive product made by the liver. It circulates all the time and converts to a substance called Angiotensin I at a rate so slow as to be completely innocuous. When blood pressure drops, special receptors in the kidney detect the drop and release a hormone called renin. Renin is a catalyst. It makes the conversion of Angiotensinogen to Angiotensin I happen much faster to create a large amount of circulating Angiotensin I. The final activation occurs in the lung where ACE converts Angiotensin I to Angiotensin II, completing the transformation from Clark Kent to Superman.

During an emergency we need Superman but on a day to day basis we want less Superman and more Clark Kent.

By using medication to inhibit ACE, we get less sodium retention and we keep blood vessels open. When the heart is overwhelmed by the amount of blood it is asked to pump forward (i.e., it receives more blood than it can pump out), it is very helpful to dilate peripheral blood vessels. Another analogy might involve a freeway system or turnpike with an inefficient tollbooth. Opening up more side streets, reduces traffic on the main freeway. Opening up peripheral blood vessels means less blood volume for the overloaded heart to pump.

Ace inhibitors help dilate the blood vessels but are not very potent relative to some other medications. Your veterinarian may prescribe other drugs, such as hydralazine or amlodipine, to accomplish this.

Disadvantages
One of the effects of the ACE inhibitor is reduced blood flow through the kidney. The kidney’s normal function depends on receiving good blood flow. If not monitored by checking blood tests that tell us about kidney function soon after starting ace inhibitors, kidney function may suffer from ACE inhibitor use particularly when it is combined with diuretics (as it usually is for heart failure) thus necessitating monitoring tests for kidney function. ACE inhibitors can also drop blood pressure excessively and may lead to retention of potassium.

Digoxin
Dogs are sometimes (less often today than in years past) prescribed digoxin in combination with the above medications. It yields several benefits:

It causes the heart to pump slightly stronger and more efficiently without pumping faster.

It reduces certain types of rhythm disturbances.

It reduces stimulation by the sympathetic nervous system to reduce heart rate.

The biggest down side is what is called a narrow therapeutic range. This means that there isn’t much leeway between a dose that helps and a toxic dose. Blood levels must be regularly monitored. Upset stomach can be a side effect. Concurrent use of certain other drugs can influence the strength of any given dose of digoxin so it is important for your veterinarian to know of all medications your pet is taking. Pets with kidney disease are most susceptible to the risk of developing these side-effects of too much digoxin.

Other Things That Might Help
Sodium Restriction
In most heart failure scenarios, the heart is unable to handle the blood volume with which it is presented. Fluid backs up and leaks out, creating either fluid in the lung (pulmonary edema) or fluid build up in the belly. In the long term, the last thing we want is to retain sodium and give the heart more blood volume to pump.

A sodium restricted diet is helpful in relieving some of the heart’s burden if the pet will eat it. Some theapeutic diets are restricted in sodium but they are so very bland, many pets will not accept them. Diets made for kidney disease are used and generally found more palatable. Using purified water for drinking may also help as many areas contain water with high sodium levels.

Poor appetite bodes poorly in heart failure as does loss of muscle tone. One must balance the blandness of the low sodium diet with keeping the pet’s appetite up.

The benefits of a sodium restricted diet do not outweigh the negative effect on health and quality of life if your pet doesn't eat or enjoy eating. The most important point here is to avoid very salty foods (pretzels, potato chips, processed ham, etc). If your pet with heart failure enjoys a sodium restricted diet, that is great. If not, feed the diet they enjoy and accept that you might need to give a bit more of the diuretic (see below) to control their heart failure.

Omega 3 Fatty Acids
Supplementation with omega 3 fatty acids is currently being researched as a possible treatment for the drastic weight loss (cardiac cachexia) that occurs with some cases of heart failure. If a pet enjoys these fishy flavored supplements, it may be a particularly helpful way to encourage appetite.

Activity Restriction?
People often ask how much restriction in exercise they should impose. Some exercise is good for the pet’s well-being and life quality. Avoid exercise that leads to excessive panting or weakness.

Learn How to Check Your Pet’s Respiratory Rate
A patient with heart failure distress will have an increased respiratory rate. A pet with controlled heart failure may have a respiratory rate that is greater than normal. It is very helpful to know what is normal for your pet and check several times daily. Simply watch the number of chest excursions during a 15-second period. A change in respiratory rate is a good sign the pet needs a check up with the vet. With cats, be sure the cat is not purring when respiratory rate is checked. Do not count panting for dogs.

Copyright 2005 - 2008 by the Veterinary Information Network, Inc. All rights reserved.
This work was originally published by Veterinary Information Network, Inc. (VIN)
and is republished with VIN's permission.

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Enalapril	Fortekor	Vetmedin	Canine Heart Health
	CHF Supplements	Benazepril	Furosemide