Congestive Heart Failure (CHF)
CHF is a syndrome or final common pathway of many types of heart disease, rather than a specific disease or diagnosis. It can be secondary to many types of heart disease, including hypertrophic and dilated cardiomyopathies, chronic valve disease, congenital diseases such as patent ductus arteriosus, pulmonic and aortic stenosis and septal defects. Anything that causes a pressure or volume overload to the heart can eventually lead to CHF.
Congestive heart failure is characterized by the build up of body fluid in the lungs (edema) or in a body cavity (effusion). Rarely right sided CHF can lead to edema of the skin.
Clinical signs associated with left sided congestive heart failure include weakness, lethargy, coughing, labored breathing, fainting.
Clinical signs associated with right sided congestive heart failure include abdominal distention, labored breathing, decreased appetite, weakness, lethargy.
If there is severe pulmonary edema or pleural effusion, this is a medical emergency and veterinary attention should be sought. Typically there will be persistent labored breathing with these problems.
Several medications may be used in your pet to control the signs of CHF. These may include one or more of the following:
Furosemide (Salix/Lasix) – a diuretic used to reduce blood volume and help remove and prevent fluid buildup in the lungs and body cavities. This medication works in the kidneys to reduce reabsorption of salt and water, thus causing more urine to be produced. Common side effects can include increased urination and thirst. Sometimes use of this medication can cause dehydration, or unmask underlying kidney disease. When using this medication, frequent rechecks of kidney values are often required.
Angiotensin converting enzyme inhibitor (ACEI) – examples include enalapril and benazrpril. These medications help counteract some of the neurohormonal problems that start with CVD, namely blood volume expansion, peripheral vasoconstriction, and ventricular fibrosis and remodeling. They have been shown in multiple veterinary studies to be beneficial in the chronic management of congestive heart failure. These medications can rarely cause decreased appetite. Idiosyncratic kidney failure has been reported, but this is rare.
Vetmedin (pimobendan) – this is an inodilator that has been used in Europe, Canada, and Australia for some time but is relatively new to the USA. It acts to increase the force and efficiency of heart muscle contraction and also acts as a peripheral vasodilator, making it easier for the heart to pump blood out to the body. Side effects may include GI upset or decreased blood pressure, appearing clinically as lethargy or weakness.
Spironolactone – this is a weak diuretic that also has some antifibrotic properties.
Digoxin – this is a medication that acts both as an antiarrhythmic for atrial fibrillation among other tachycardias and as a weak positive inotrope (helps heart muscle contraction). This medication can cause loss of appetite, weakness, lethargy and arrhythmias. It is very important to closely monitor appetite and home and blood levels when starting this medication.
Of course, other medications may be incorporated into your pet’s therapy as indicated by the history, clinical signs, & diagnostic test results. In addition, a moderately sodium restricted diet may be prescribed.
If your pet has had an episode of CHF, it will likely need to be on medication for the remainder of its life. Typically the diseases that lead to CHF are progressive and recurrent bouts of CHF may occur, as well as other sequelae specific to the underlying heart disease. The dynamic nature of CHF mandates frequent rechecks and vigilant monitoring of respiration and attitude at home. One good way to help stay on top of things is to count the sleeping respiratory rate at home. The rise and fall of the chest wall is one breath. Normal in dogs and cats is < 40 breaths/minute. Establish a baseline for your pet, and if you notice the respiratory rate increases persistently over several days this may be an indication that fluid is building up again.