Enalapril is an angiotensin-converting enzyme (ACE) inhibitor that is FDA-approved for the treatment of congestive heart failure (CHF) in dogs. Sold under the human brand name Vasotec and the veterinary brand Enacard, enalapril is a cornerstone of heart failure management and is also used for protein-losing kidney disease and hypertension. It is one of the three medications in the standard “triple therapy” for canine CHF (along with furosemide and pimobendan). Enalapril requires a veterinary prescription and is available as an affordable generic.
What Is Enalapril Used For?
Enalapril is prescribed for cardiovascular and kidney conditions:
- Congestive heart failure (CHF) — mitral valve disease (MMVD), dilated cardiomyopathy (DCM)
- Heart failure management — as part of triple therapy with furosemide and pimobendan
- Protein-losing nephropathy — kidney disease with excessive protein loss in urine
- Systemic hypertension — though amlodipine is generally preferred in cats
- Chronic kidney disease — to reduce proteinuria and slow kidney disease progression
- Pre-clinical heart disease — some cardiologists recommend ACE inhibitors in early-stage disease
In cats, benazepril is often preferred over enalapril because benazepril has partial liver excretion (less dependent on kidney function), which can be advantageous in cats with concurrent kidney disease.
How Does Enalapril Work?
Enalapril is a prodrug that is converted by the liver to its active form, enalaprilat. Enalaprilat inhibits angiotensin-converting enzyme (ACE), which normally converts angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor (narrows blood vessels) and stimulates aldosterone release (promotes sodium and water retention).
By blocking ACE, enalapril:
- Dilates blood vessels (reduces afterload — the resistance the heart pumps against)
- Reduces fluid retention (decreases preload)
- Lowers blood pressure
- Reduces proteinuria in kidney disease by dilating the efferent arteriole in the kidney glomerulus
- Modulates neurohormonal activation — counteracts the harmful RAAS (renin-angiotensin-aldosterone system) activation that worsens heart failure
The net effect is reduced workload on the failing heart and improved cardiac output.
Dosage
Your veterinarian will determine the exact dose for your pet.
Dogs
| Dog’s Weight | Typical Dose | Frequency |
|---|---|---|
| 10 lbs (4.5 kg) | 1.25-2.5 mg | Every 12-24 hours |
| 20 lbs (9 kg) | 2.5-5 mg | Every 12-24 hours |
| 40 lbs (18 kg) | 5-10 mg | Every 12-24 hours |
| 60 lbs (27 kg) | 5-10 mg | Every 12-24 hours |
| 80+ lbs (36+ kg) | 10-20 mg | Every 12-24 hours |
Standard dose: 0.5 mg/kg every 12-24 hours.
Cats
| Cat’s Weight | Typical Dose | Frequency |
|---|---|---|
| 6-12 lbs (2.7-5.4 kg) | 1.25-2.5 mg | Every 12-24 hours |
Standard feline dose: 0.25-0.5 mg/kg every 12-24 hours.
How to Give Enalapril to Your Dog or Cat
- Available as tablets (2.5 mg, 5 mg, 10 mg, 20 mg).
- Can be given with or without food. Food does not significantly affect absorption.
- Give at consistent times each day for steady blood pressure control.
- Do not skip doses in heart failure patients — inconsistent dosing can worsen the condition.
- If you miss a dose, give it as soon as you remember. If the next dose is near, skip and resume the regular schedule.
- Your veterinarian will likely start at a lower dose and adjust based on your pet’s response and blood work.
Side Effects
| Common Side Effects | Serious Side Effects (Contact Your Vet) |
|---|---|
| Mild decrease in appetite | Significant drop in blood pressure (weakness, collapse, fainting) |
| Mild GI upset | Elevated kidney values (increased BUN, creatinine) |
| Mild lethargy | Hyperkalemia (high potassium — muscle weakness, heart rhythm changes) |
| Severe vomiting or diarrhea | |
| Facial swelling (angioedema — rare) |
The most clinically important concern is worsening kidney function, especially when enalapril is combined with furosemide (which reduces blood flow to the kidneys). Regular monitoring of kidney values and electrolytes is essential. Most dogs tolerate enalapril well when appropriately dosed and monitored.
Drug Interactions
- Furosemide and other diuretics: Commonly combined for CHF, but additive blood pressure lowering and increased risk of kidney function changes. Close monitoring required.
- NSAIDs (carprofen, meloxicam): Can reduce ACE inhibitor effectiveness and worsen kidney function. Use with caution.
- Potassium supplements or potassium-sparing diuretics (spironolactone): Risk of hyperkalemia. Monitor potassium levels.
- Pimobendan (Vetmedin): Standard combination in CHF management. Generally well-tolerated together.
- Amlodipine: Can be combined for blood pressure control, but monitor for hypotension.
Contraindications
- Known hypersensitivity to enalapril or other ACE inhibitors
- Bilateral renal artery stenosis (rare)
- Severe dehydration or hypovolemia — correct before starting
- Pregnant animals — ACE inhibitors can cause fetal harm
- Use with caution in animals with pre-existing kidney impairment (may worsen initially)
Storage
- Store at controlled room temperature, 68-77degF (20-25degC).
- Protect from moisture.
- Keep in original container.
- Keep out of reach of children and pets.
Cost & Availability
Enalapril is a widely available generic at very low cost.
- Approximate cost: $5-$15 per month for most dogs and cats
- Available forms: 2.5 mg, 5 mg, 10 mg, 20 mg tablets
- Can be filled at human pharmacies with a veterinary prescription
- Enacard (veterinary brand) is also available but more expensive
- One of the most affordable heart failure medications
Frequently Asked Questions
Why is enalapril important for heart failure? Heart failure activates the renin-angiotensin-aldosterone system (RAAS), which causes blood vessel constriction and fluid retention — making the heart work harder. By blocking ACE, enalapril counteracts this harmful cycle, reducing the workload on the heart and helping the other medications (furosemide and pimobendan) work more effectively.
Does my pet need blood work while on enalapril? Yes. Kidney values (BUN, creatinine) and electrolytes (potassium) should be checked before starting enalapril, within 1-2 weeks of starting or any dose change, and then every 3-6 months for stable patients. This monitoring is especially important when enalapril is combined with furosemide.
Is benazepril better than enalapril for cats? Many veterinarians prefer benazepril (Lotensin/Fortekor) for cats because it has dual excretion pathways (liver and kidney), making it less dependent on kidney function. Since many cats needing ACE inhibitors also have kidney disease, benazepril’s pharmacokinetics may be advantageous. Both drugs are effective ACE inhibitors.
Can enalapril be used for kidney disease? Yes, enalapril (and other ACE inhibitors) can reduce proteinuria (protein loss in the urine) in dogs and cats with protein-losing kidney disease. By dilating the efferent arteriole in the kidney glomerulus, ACE inhibitors reduce glomerular pressure and protein leakage.
Sources & References
- FDA - Enacard (Enalapril) Product Information
- Merck Veterinary Manual - ACE Inhibitors
- ACVIM Consensus Statement on Heart Failure
- VCA Hospitals - Enalapril
- PetMD - Enalapril for Dogs and Cats
Verification Notes
Enalapril’s description as “ACE inhibitor. FDA-approved for CHF in dogs. Monitor kidney values and electrolytes.” and the note that “Benazepril is preferred over enalapril in cats because it is partially excreted via the liver” are directly confirmed by the research corpus. The standard triple therapy (enalapril + furosemide + pimobendan) is well-documented in veterinary cardiology guidelines.