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What is enalapril used for in cats?

Enalapril treats congestive heart failure and hypertension in cats
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By | Jan. 10, 2025 Medically reviewed by Emma Ryan, DVM
Orange cat looking into a pill bottle: What is enalapril used for in cats?

Key takeaways

  • Enalapril is used to treat congestive heart failure in cats and as a second-line treatment for high blood pressure.

  • The standard enalapril dosage for cats is 1.25–2.5 mg, taken by mouth once or twice a day.

  • The most common side effects of enalapril in cats are decreased appetite and lethargy.

  • Do not give enalapril to cats with known allergies to enalapril or other ACE inhibitors.

In this article:

Veterinarians primarily use enalapril to treat cats with congestive heart failure (CHF). Enalapril lowers blood pressure, but veterinarians only use it as a second-step treatment for feline hypertension. Enalapril is safe for cats, but treatment requires regular blood tests and visits to the veterinarian to monitor therapy and prevent adverse effects.

What is enalapril used for in cats?

Veterinarians use enalapril to treat cats with congestive heart failure, but they also use it as a second-step drug to treat high blood pressure.

Enalapril is an angiotensin-converting enzyme inhibitor. ACE inhibitors block the body’s production of angiotensin II, a hormone that tightens blood vessels and raises blood pressure. Lowering blood pressure is its primary effect, but it also reduces the heart’s workload and prevents kidney damage.

Congestive heart failure

Congestive heart failure is a condition in which the heart cannot sufficiently pump blood to the rest of the body. It is a progressive disease because the heart slowly adds muscle to make up for the reduced output. This building of heart muscle is called heart remodeling. Unfortunately, the thickened muscle reduces the amount of blood the heart can hold, so the heart gradually gets worse at pumping enough blood to the body.

Heart failure is a common condition in cats. It has many causes, but one major cause is the thickening of the heart walls (hypertrophic cardiomyopathy), the most common form of heart disease in cats.

When heart disease progresses to heart failure, veterinarians prescribe medications to increase the amount of blood that the heart pumps and slow the progress of the disease. They don’t use one type of medicine but several:

When a veterinarian prescribes enalapril, caregivers usually only need to give one dose daily. Some veterinary professionals may prescribe twice-daily doses. 

High blood pressure

Hypertension is a persistent elevation in blood pressure. It slowly damages a cat’s vital organs, especially the kidneys, eyes, brain, and heart. Although some cats have high blood pressure with no discernible cause, the most common cause of feline hypertension is chronic kidney disease (about 60% of diagnoses). Other causes include overactive thyroid or adrenal gland problems. 

Doctors treat people with blood pressure drugs as soon as they show persistent high blood pressure. However, the general consensus in veterinary medicine is to start treating high blood pressure when there are signs of organ damage. 

Calcium channel blockers are the treatment of choice for feline hypertension. The recommended starting drug is amlodipine. Veterinarians will add or substitute enalapril if treatment is ineffective or if the cat has kidney dysfunction and protein in the urine (proteinuria). 

Proteinuria

Cats with high blood pressure typically have chronic kidney disease, and cats with chronic kidney disease typically have high blood pressure. Veterinarians typically spot feline kidney dysfunction through blood tests that show elevated creatinine and protein levels. When urine has excess proteins in it, that condition is called proteinuria.

Kidney dysfunction typically starts with damage to the kidneys’ most delicate blood-filtering system, the glomeruli. These tiny, thin, and delicate blood vessels are where water, electrolytes, and other substances are pushed out of the blood into the urine. High blood pressure damages these blood vessels. 

When glomeruli get damaged, the kidneys lose the ability to filter blood. The body responds by increasing blood pressure in the kidneys. The increased blood pressure pushes out more water, electrolytes, and other wastes. It also pushes out more protein, so excess protein in the urine indicates something is going wrong. The increased blood pressure damages even more blood vessels, so kidney disease gradually worsens. The end result is kidney failure. 

When a cat with high blood pressure also has proteinuria, that’s a sign that high blood pressure is damaging the kidneys. The standard treatment is to add an ACE inhibitor to a blood pressure medication such as amlodipine. ACE inhibitors lower blood pressure primarily in the smallest arteries (peripheral arteries), particularly those in the kidneys. In this way, enalapril helps slow the progress of kidney disease. 

Is enalapril safe for cats?

Enalapril is safe for cats, but not all cats. Veterinarians will never give enalapril to a cat with:

  • A history of allergic reactions to enalapril or other ACE inhibitors
  • Certain types of heart conditions

Veterinarians use enalapril with caution in cats who are pregnant, lactating, dehydrated, or have:

  • Kidney disease
  • Severe liver damage
  • Low sodium
  • Blood disorders

Side effects of enalapril in cats

The most common side effects of enalapril in cats are:

  • Loss of appetite
  • Listlessness

More serious but rare side effects include:

  • Low blood pressure (hypotension)
  • Kidney damage
  • Elevated potassium
  • Hypersensitivity reactions

Contact a veterinarian if side effects worsen or you notice any signs of a possible severe side effect, including:

  • Rash
  • Fever
  • Tiredness
  • Collapse

Interactions of enalapril with other pet meds

To avoid possible drug interactions, tell the veterinarian about all drugs that the cat is on, particularly:

  • Other drugs that lower blood pressure
  • Drugs that make the cat pee (diuretics)
  • Insulin and any other drugs that treat feline diabetes
  • Drugs and supplements that increase potassium levels
  • Non-steroidal anti-inflammatory drugs (NSAIDs)

These drugs aren’t prohibited, but the veterinarian may need to adjust dosages.

Caregivers can give their cat CBD and many other supplements besides potassium. However, they should consult with the veterinarian first. 

Enalapril dosage for cats

The standard enalapril dosage for cats is 1.25–2.5 mg, once or twice daily. In terms of body weight, that’s about 0.25–0.5 mg per kilogram. 

Plumb’s Veterinary Drug Manual lists the following specific dosages:

  • For adjunctive treatment of heart failure: 1.25–2.5 mg given by mouth once daily OR 0.25–0.5 mg/kg given by mouth once daily
  • For adjunctive treatment of proteinuria and hypertension associated with chronic kidney disease: 0.25–0.5 mg/kg given by mouth once or twice a day 
  • As a second step treatment for hypertension: 0.25-0.5 mg/kg given by mouth once or twice a day

Enalapril is not FDA-approved for use in cats, but caregivers can give their cats either human or veterinary formulations. Enalapril tablets for people are scored so they can be divided into smaller doses, as small as 1.25 mg. Enalapril oral solution makes for easier and more precise dosing.

Can cats overdose on enalapril?

Do not exceed the prescribed dose.

Cats can overdose on enalapril. Too much enalapril will lower blood pressure too much. A high enough overdose will lower blood pressure so much that the cat could die. 

Caregivers should call a veterinarian or the ASPCA Animal Poison Control Center if an overdose is suspected. 

Can I give my cat enalapril every day?

Enalapril is typically a long-term treatment. Cats with heart failure may be on the medicine for the rest of their lives. 

Enalapril is safe for daily, long-term treatment, but a veterinarian will need to regularly check the cat and perform blood tests to monitor treatment. 

How to give your cat enalapril

Giving a cat enalapril is no different than giving any other tablet or oral solution. It’s important, though, to give doses consistently. If the cat gets two doses daily, one should be in the morning and the other at night. 

  • Give your cat enalapril doses exactly as prescribed.
  • Do not miss doses. Do not stop administering enalapril to your cat until told to do so by the veterinarian. 
  • A dose of enalapril can be given with or without food. If the cat throws up a dose, try giving future doses with food.
  • If you don’t know how to administer tablets to a cat, ask a veterinary professional to demonstrate the most effective procedure.
  • If you need to divide tablets in two, ask a veterinary professional to demonstrate the proper procedure.
  • Enalapril oral solution may need to be shaken before measuring a dose. Please read the instructions to avoid underdosing or overdosing the cat.
  • Always measure doses using the calibrated oral syringe or dropper with the oral solution.
  • If a dose is missed, give it as soon as possible. If it’s almost time for the next dose, skip the missed dose and give the next dose as scheduled. 
  • Store enalapril tablets at room temperature, protected from moisture.
  • Store enalapril oral solution in a refrigerator. For veterinary formulations, storage instructions should be written on the prescription label or packaging. 

Enalapril alternatives for cats

Enalapril and other ACE inhibitors are the first-line drugs for heart failure treatment in cats. If there’s a problem, alternative treatment options include: 

For feline hypertension, the drugs of choice are calcium channel blockers such as amlodipine. If they don’t work or the cat has kidney disease, veterinarians may add enalapril or a similar ACE inhibitor. If ACE inhibitors can’t be used, other treatment options include:

Summary

Veterinarians use enalapril to treat serious medical conditions in cats, including heart failure and high blood pressure. Caregivers should consistently give one or two doses daily to their pet cats. Adverse effects are minimal, but all appointments with the veterinarian should be kept to ensure the treatment is successful.

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