Heart Disease - Medications

Overview

Angiotensin converting enzyme (ACE) inhibitors interfere with the body’s natural system that maintains fluid levels and blood pressure. This system is often put into overdrive during congestive heart failure, resulting in fluid buildup. By blocking this system, ACE inhibitors help the body achieve a normal fluid amount. This keeps the lungs free of excess fluid. ACE inhibitors also open blood vessels, allowing for more blood flow to tissues.

Uses

ACE inhibitors are used for treating congestive heart failure as they help the body maintain a normal fluid balance. ACE inhibitors are also used to treat high blood pressure, and they can be used to reduce protein loss from the kidneys. Sometimes ACE inhibitors are used in animals with moderate to marked heart enlargement, before the onset of congestive heart failure.

Administration

ACE inhibitors are available as tablets. They are usually given once or twice daily.

Side Effects

ACE inhibitors can cause low blood pressure which may be noted as lethargy, weakness or difficulty standing. ACE inhibitors can occasionally cause diarrhea or vomiting. ACE inhibitors are often given with a diuretic, like furosemide, and can cause increased kidney values on bloodwork.

Unlike in humans where coughing is a common side effect of ACE inhibitors, ACE inhibitors usually do not cause coughing in pets (however many dogs who need an ACE inhibitor are already coughing!).

Follow-up

Before your pet is put on an ACE inhibitor, your veterinarian will likely want initial bloodwork (especially kidney values and electrolytes). After starting an ACE inhibitor, your veterinarian will retest bloodwork in 5-14 days to check the kidney (BUN and creatinine) and electrolyte (sodium, chloride, and potassium) levels. Your pet’s blood pressure may also need to be periodically measured, especially if your pet has weakness or lethargy.

Overview

Amiodarone is an antiarrhythmic drug. By blocking an electrical signal/channel that is creating an abnormal heartbeat, amiodarone helps reduce the frequency of the arrhythmia, reduce the frequency of collapse, and hopefully will prevent sudden death.

Uses

Amiodarone is used to treat dogs with very serious arrhythmias or an arrhythmia that has not responded to other treatments. Specific arrhythmias treated with amiodarone include ventricular tachycardia, supraventricular tachycardia, and atrial fibrillation.

Administration

Amiodarone is available in an injectable form (used in the hospital) and as tablets. Tablets are usually given twice daily for the first 5-7 days, and then once daily long-term.

Side Effects

Amiodarone can cause side effects like reduced appetite and vomiting. On bloodwork, amiodarone may cause increased liver enzymes indicating liver damage. This damage can usually be reversed if the medication is stopped. Amiodarone can also rarely affect the function of the thyroid gland.

Follow-up

The effectiveness of amiodarone is usually evaluated by looking at recheck ECGs or by looking at a long ECG tracing using a Holter monitor. Your veterinarian may want to periodically retest bloodwork, perhaps every few months, to check on the liver enzymes or the thyroid function.

Overview

Amlodipine is a drug that causes widening of the blood vessels in the body. This can help treat systemic hypertension (high blood pressure).

Uses

Amlodipine is most commonly used to treat hypertension (high blood pressure). It is also used in certain situations to treat dogs with congestive heart failure.

Administration

Amlodipine is available as a tablet or a liquid. It is usually given once or twice daily.

Side Effects

Amlodipine can cause weakness, lethargy, or collapse. These side effects can be related to low blood pressure and might indicate that the dosage was higher than an animal needed. Dose adjustment usually resolves the side effects. Excessive growth of gum tissue in the mouth can also be seen with amlodipine.

Follow-up

Your pet’s blood pressure will usually be checked shortly after starting amlodipine.

Overview

Atenolol is a beta-blocker drug. Beta-blocker drugs prevent the heart from reacting to high amounts of adrenalin in the bloodstream, which sometimes happens with excitement, exercise or heart failure. By blocking the effects of adrenalin, atenolol helps to slow the heart rate, reduce the frequency of the arrhythmia and perhaps slow the progression of heart disease.

Uses

Atenolol is sometimes used to treat hypertrophic cardiomyopathy (HCM) in cats, especially when there is an obstruction inside the heart. Dogs with pulmonic or subaortic stenosis may also be prescribed atenolol. Atenolol is sometimes used to control arrhythmias, and it might be used in conjunction with another antiarrhythmic drug like mexiletine. Atenolol is not usually used in pets with uncontrolled congestive heart failure.

Administration

Atenolol is available as a tablet. It is usually given twice daily.

Side Effects

Atenolol can cause weakness, lethargy, fainting, slow heart rate, low blood pressure, or it can sometimes make heart failure harder to control. These side effects often indicate the dosage is too high. Dose adjustment usually resolves the side effects.

Follow-up

Follow-up for a pet on atenolol may involve recheck echocardiograms or monitoring for control of the arrhythmia via frequent electrocardiograms (ECGs) or a Holter recording. Cats that are taking atenolol for HCM will have periodic recheck echocardiograms.

Overview

Carvedilol is a beta-blocker drug. Beta-blocker drugs prevent the heart from reacting to high amounts of adrenalin in the bloodstream, which sometimes happens with excitement, exercise or heart failure. By blocking the effects of adrenalin, carvedilol helps to slow the heart rate, reduce the frequency of arrhythmia and perhaps slow the progression of heart disease.

Uses

Carvedilol can be used to control arrhythmias in dogs. Carvedilol is also sometimes used in cats with HCM or arrhythmias. Carvedilol and related drugs are usually not started in dogs or cats that have significant difficulty breathing due to heart failure, at least not until the difficulty breathing is improved.

Administration

Carvedilol is available as a tablet. It is usually given twice a day. Your pet will need to become used to carvedilol, and the dosage will often be slowly increased over the first several weeks until a desired or target dose is reached.

Side Effects

Carvedilol can cause weakness, lethargy, fainting, slow heart rate, low blood pressure, or it can sometimes make heart failure harder to control. These side effects often indicate the dosage is too high. Dose adjustment usually resolves the side effects.

Follow-up

Generally, follow-up for a pet on carvedilol will involve monitoring for control of the arrhythmia via frequent electrocardiograms (ECGs) or a Holter recording. Routine examination will also be recommended to monitor for progression of heart disease.

Overview

Clopidogrel is a medication that inhibits the clotting of blood. It prevents small elements of the blood, called platelets, from gathering together to create an unwanted clot.

Uses

Clopidogrel is often used in cats with an enlarged left heart or a prior episode of arterial thromboembolism (ATE) because of its ability to reduce the risk for blood clots – minimizing the chance that a clot will form in the body and cut off blood supply to a rear limb or other parts of the body. Clopidogrel is also given to dogs at risk for clot formation.

Administration

Clopidogrel is available as a tablet. It is usually given once a day.

Side Effects

Clopidogrel can cause unwanted bleeding because of its ability to reduce blood clotting. This can appear as spots of red on your pet’s gums or belly, blood-tinged urine, or bleeding from a small wound that doesn’t stop.

Clopidogrel has a bitter taste, and some cats can get foaming at the mouth or drooling during or after giving the medication. If this occurs, you can try putting the clopidogrel tablet into an empty gelatin capsule, and then giving the gelatin capsule to your cat. Some people try to compound it into a liquid formulation, which does not always hide the taste of clopidogrel, although using a marshmallow flavor might help hide the taste for some cats. View our tips on administering pills.

Follow-up

If your pet is on clopidogrel, you should monitor for bleeding and let your veterinarian know if you see any problems.

Overview

Digoxin is a drug that slows the heart rate and helps to control arrhythmias. It is being used less frequently now due to the development of better drugs and the potential for digoxin-related toxicity.

Uses

Digoxin is used to help treat congestive heart failure and to control specific arrhythmias such as atrial fibrillation and supraventricular tachycardia. Currently, the most common use is for dogs that have both atrial fibrillation and congestive heart failure.

Administration

Digoxin is available as a tablet. It can be difficult to calculate the correct dose for any individual pet, and sometimes the initial dose is too high or too low. Your veterinarian might want to get blood digoxin levels, often done about 8 hours after giving the pill, to help determine the best dose for your pet. Dogs are usually dosed twice daily.

Side Effects

Digoxin has a potential for toxicity if too high a dose is selected. Side effects can include reduced appetite, gastrointestinal signs (such as vomiting or diarrhea), depression or lethargy, and even worsening of arrhythmias. Side effects usually resolve if the dose is reduced.

Follow-up

Because of its toxicity potential, many veterinarians recommend bloodwork to check digoxin blood levels about 5-8 days after beginning treatment.

Overview

Diltiazem is an antiarrhythmic drug. By blocking an electrical signal/channel that is creating an abnormal heartbeat, diltiazem helps reduce the frequency of arrhythmia and/or controls the speed of the heart rate.

Uses

Diltiazem is used to treat specific arrhythmias such as supraventricular tachycardia and atrial fibrillation. It is sometimes used to help treat systemic hypertension (high blood pressure) or hypertrophic cardiomyopathy (HCM) in cats.

Administration

Diltiazem is available as a tablet or in an injectable form for use in the hospital. It also comes in a sustained release capsule that contains tablets inside, but almost all pets are too small to take the entire capsule. Diltiazem overdose can be lethal, so it is very important to ensure that the correct dose is given. It is usually given 2-3 times daily.

Side Effects

Diltiazem can cause lethargy, weakness, or collapse. Sometimes these effects are from a slow heart rate and sometimes it is due to low blood pressure. It may also cause a decreased appetite. Side effects are especially common when the dose given to an animal was higher than they needed, and the side effects often resolve on a lower dose.

Follow-up

Pets on diltiazem will require a periodic examination to ensure the heart rate and rhythm are normal. Blood pressure might also be rechecked.

Overview

Furosemide is a diuretic, a type of drug that removes fluid from the body by increasing urination (sometimes called a water pill). The removal of fluid improves breathing and creates less work for the heart. When fluid builds up as a result of a failing heart, symptoms such as coughing and difficulty breathing can occur. Furosemide helps treat these symptoms.

Uses

Furosemide is used to remove fluid buildup in the lungs, chest, and abdomen due to congestive heart failure. Furosemide is a drug used in the treatment of most pets with congestive heart failure.

Administration

Furosemide is available as pills, an injectable liquid form, or as a liquid for oral administration (but many animals do not like the taste). Dosage depends on the individual needs and responses of each pet. Your veterinarian will try to find the lowest dose possible based on the management of your pet’s symptoms. Finding the optimal dose may take some time and the best dose for your pet may change over time.

Dogs are usually started with giving the medication once to twice a day, but dosing can be increased to three times a day if needed, or more often in an emergency setting. Your veterinarian may also increase the amount of furosemide that is given with each dose.

Cats with milder heart failure are sometimes started on a lower dose of furosemide. They may be given a dose once a day, twice a day, or even every other day.

Side Effects

Because furosemide causes the body to lose fluid, if the dose is too high it can cause dehydration. Furosemide can also cause the kidney values to rise, especially if the dose is too high or in animals with preexisting kidney disease. Furosemide can also cause low blood potassium levels, especially in animals who are not eating well.

Pets on furosemide should always have free access to water. They may need to urinate more frequently, especially in the first several hours after receiving a dose. It is important to take your dog out more frequently (or have pee pads available) and for the litterbox to be cleaned more often for cats on furosemide. In some animals, the most impressive urine production is within the first 4 hours of giving the medication. Because of this, you may want to avoid giving the medication to dogs right before going to bed – you might need to wake up to let them out, or you might find accidents on the floor in the morning.

Follow-up

5-10 days after beginning treatment with furosemide, your veterinarian will likely want to measure kidney (BUN and creatinine) and electrolyte (sodium, chloride, and potassium) values in your pet’s blood. Once these values are steady, the bloodwork will usually need to be rechecked every 3-6 months. Your pet’s furosemide dosage and administration may need to be adjusted as your pet’s heart disease and symptoms change.

If your pet’s symptoms (like coughing or difficulty breathing) worsen while on furosemide, contact your veterinarian as the dosage may need to be adjusted. For Tufts clients, if your animal’s breathing rate is above 35 breaths per minute when they are at rest, especially if your pet has extra belly wall motion while breathing, you should give an extra dose of furosemide. If difficulty breathing persists after the extra dose of furosemide then a visit to the emergency service is recommended.

Overview

Mexiletine is an antiarrhythmic drug. By blocking an electrical signal/channel that is creating an abnormal heartbeat, mexiletine helps reduce the frequency of the arrhythmia, reduce the frequency of collapse, and hopefully prevent sudden death.

Uses

Mexiletine is most often used for ventricular arrhythmias but is sometimes used in other situations as well.  Mexiletine is sometimes used in conjunction with another antiarrhythmic drug.

Administration

Mexiletine is available as a capsule. It is usually given three times a day.

Side Effects

Mexiletine can cause decreased appetite, diarrhea, and other gastrointestinal side effects. It is better tolerated and less likely to cause intestinal upset if it is given with some food.

Follow-up

Generally, follow-up for a pet on mexiletine will involve monitoring for control of the arrhythmia via frequent electrocardiograms (ECGs) or a Holter recording.

Overview

Pimobendan increases the heart’s strength of pumping. It also widens or opens up blood vessels. These actions allow more blood to be pumped to the rest of the body with each heartbeat.

Uses

Pimobendan is commonly used to treat congestive heart failure in dogs and cats, although the drug is only FDA approved for dogs. It is also used in dogs before noticeable symptoms of heart disease have appeared, but when significant heart enlargement has been identified by echo and chest x-rays. Pimobendan is sometimes used in cats with cardiomyopathy, but veterinarians might not use the medication if a cat has HCM with an obstruction in the heart.

Administration

Pimobendan is available in chewable tablets in the US and in other formulations worldwide. Pimobendan might not be stable when compounded, so whenever possible use an official formulated version of the drug. Pimobendan is usually given twice a day.

Side Effects

Pimobendan is a very safe medication and side effects are uncommon (compared to most heart medications). Occasionally, pets may have diarrhea as a side effect of the medication. Cats can sometimes get overly excited by the medication and become more active than normal or just feel unwell.

Follow-up

Because of its safety, there is no specific follow-up for this medication. Routine review of your pet’s medications, with recheck exams by your veterinarian, should usually occur every 3-6 months.

Overview

Entresto is a relatively new medication that has been successful in people with certain types of heart disease. It has only recently been used in pets with heart disease. Entresto is a combination of two drugs that help the heart pump blood to the body.

Uses

Because Entresto is a very new drug, it is primarily used for dogs with recurrent symptoms of congestive heart failure.

Administration

Entresto is available as a tablet. It is usually given twice daily.

Side Effects

Entresto can cause low blood pressure which may be noted as lethargy, weakness or difficulty standing. It may also cause diarrhea or vomiting. Entresto is often given with a diuretic, like furosemide, and can cause increased kidney values on bloodwork. Entresto should not be given at the same time as an ACE inhibitor like enalapril, benazepril or lisinopril.

Follow-up

Before your pet is put on an Entresto, your veterinarian will likely want initial bloodwork (especially kidney values and electrolytes). After starting Entresto, your veterinarian will probably want to retest bloodwork in 5-14 days to check the kidney (BUN and creatinine) and electrolyte (sodium, chloride, and potassium) levels. Your pet’s blood pressure may also need to be periodically measured, especially if your pet has weakness or lethargy.

Overview

Sildenafil is a drug that causes widening of the blood vessels in the lungs. This can help treat pulmonary hypertension (high blood pressure in the lungs).

Uses

Sildenafil is most commonly used to treat pulmonary hypertension (high blood pressure in the lungs). It is also used in certain situations to treat dogs with congestive heart failure.

Administration

Sildenafil is available as a tablet or a liquid (but pets often do not like the taste of the liquid). It is usually given two or three times daily.

Side Effects

Sildenafil can cause weakness, lethargy, or collapse. These side effects often indicate the dosage is too high. Dose adjustment often resolves the side effects. Other side effects could include skin flushing or stomach upset.

Follow-up

Follow-up for a pet on sildenafil is guided by their underlying heart or lung disease. Sometimes a recheck echocardiogram is needed to see if the pressure in the lungs has dropped or whether a dose adjustment is recommended.

Overview

Sotalol is primarily an antiarrhythmic drug. By blocking an electrical signal/channel that is creating an abnormal heartbeat, sotalol helps return pets to normal heart rhythm, or reduce the frequency of abnormal heartbeats.

Uses

Sotalol is used mostly in the treatment of ventricular arrhythmias, especially for Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC). Sotalol is also used in treating some supraventricular arrhythmias (a fast heart rate originating from the upper chambers of the heart).

Administration

Sotalol is available as a tablet and is usually given twice daily.

Side Effects

Sotalol can cause weakness or fainting. It can cause a worsening of congestive heart failure and should be used with caution in patients with active difficulty breathing due to congestive heart failure.

Follow-up

Generally, follow-up for a pet on sotalol will involve monitoring for control of the arrhythmia via frequent electrocardiograms (ECGs) or a Holter recording. Some owners also choose to monitor with at-home ECG recordings.

Overview

Spironolactone is a diuretic (sometimes called a water pill), a type of drug that removes fluid from the body by increasing urination. Spironolactone removes fluid without removing potassium (unlike furosemide). Spironolactone blocks a hormone called aldosterone, and this may have additional benefits to the heart muscle and throughout the body.

Uses

Spironolactone is often used to treat congestive heart failure, and it is often used in combination with furosemide (another diuretic).  Spironolactone is often used as part of the routine management of congestive heart failure in dogs. It is sometimes added to the treatment plan when furosemide alone is not controlling the symptoms of congestive heart failure.

Administration

Spironolactone is available in a variety of tablet formulations, sometimes combined with other drugs, such as hydrochlorothiazide or benazepril. Dogs and cats might be prescribed spironolactone for once a day or twice a day dosing. Some veterinarians recommend that spironolactone should be given with food.

Side Effects

Spironolactone can cause gastrointestinal upset such as loss of appetite, vomiting or diarrhea. Spironolactone can be given with food to minimize this side effect or hide the taste of the drug.  Spironolactone can also affect electrolytes (especially potassium) and cause a rise in kidney blood values.  Face or ear scratching is an uncommon but occasional side effect in cats.

Follow-up

Shortly after starting your pet on spironolactone, your veterinarian will likely want to recheck bloodwork. Spironolactone can cause an elevation in kidney values (BUN and creatinine) and alterations in electrolytes (sodium, chloride, and potassium) levels. Bloodwork is often rechecked periodically to make sure the potassium levels and kidney values are okay.

Overview

Torsemide is a diuretic (sometimes called a water pill), a type of drug that removes fluid from the body by increasing urination. Torsemide blocks a hormone called aldosterone, and this may have additional benefits to the heart muscle and throughout the body.

Uses

Torsemide is sometimes used as a first-choice diuretic for congestive heart failure, and in other situations, it is used in advanced congestive heart failure that is no longer controlled by other diuretics (such as furosemide and spironolactone). Torsemide may be prescribed in addition to furosemide or it may be swapped to take the place of furosemide.

Administration

Torsemide is available as a tablet. It is usually given once to twice daily.

Side Effects

Because torsemide causes the body to lose fluid, if the dose is too high it can cause dehydration. Torsemide can also cause the kidney values to rise, especially if the dose is too high or in animals with preexisting kidney disease. Torsemide can also cause low blood potassium levels, especially in animals who are not eating well.

Pets on torsemide should always have free access to water. They may need to urinate more frequently. It is important to take your dog out more frequently (or have pee pads available) and for the litterbox to be cleaned more often for cats on torsemide. In some animals, the most impressive urine production is within the first 4 hours of giving the medication. Because of this, you may want to avoid giving the medication right before going to bed – you might need to wake up to let them out or find accidents on the floor in the morning.

Follow-up

5-10 days after beginning treatment with torsemide, your veterinarian will likely want to measure kidney (BUN and creatinine) and electrolyte (sodium, chloride, and potassium) values in your pet’s blood. Once these values are steady, the bloodwork will usually be rechecked every 3-6 months. Your pet’s torsemide dosage and administration may need to be adjusted as your pet’s heart disease and symptoms change.