Enalapril for Dogs: Side Effects and What It Does
By Dr. Zubair Khalid, DVM, MS, PhD ·
Enalapril for dogs side effects are usually mild and manageable, but some dogs develop vomiting, lethargy, or rising kidney values that need veterinary attention. Most dogs tolerate this heart and kidney medication well when the dose is set correctly and monitored. The goal of this article is to help you tell a normal adjustment period from a true problem.
This article is educational and is not a substitute for veterinary diagnosis or treatment.
Quick Answer
- Enalapril is an ACE inhibitor used for heart disease, high blood pressure, and certain kidney diseases in dogs [1].
- Mild tiredness or a slightly lower energy level in the first days can be an expected adjustment, but ongoing lethargy is not normal.
- Vomiting, diarrhea, weakness, or fainting can signal low blood pressure or an overdose and need a call to your veterinarian [1].
- Kidney values are typically rechecked about 1 to 2 weeks after starting an ACE inhibitor because these drugs can worsen renal function in some dogs [2].
- Never change or stop the dose on your own, and never give a double dose to make up for a missed one.
What Enalapril Does and Why Veterinarians Prescribe It
Enalapril is an angiotensin-converting enzyme inhibitor, often called an ACE inhibitor [1]. It is regularly prescribed to dogs to treat hypertension, cardiomyopathy, and heart disease [1]. It can also be used for kidney diseases such as chronic renal failure and protein-losing nephropathies [1].
That range surprises many owners. A heart medication that also helps kidneys sounds odd until you understand how the drug works. In heart failure, the body's hormone systems tighten blood vessels and hold onto fluid, which makes the heart work harder. In kidney disease, the same hormone system can push protein out through the kidneys and raise blood pressure inside the filtering units. Enalapril interrupts that process in both places.
Your veterinarian may prescribe enalapril alone or alongside other heart medications. If your dog takes more than one cardiac drug, it helps to know what each one does. Our guide to Vetmedin side effects in dogs covers the other medication commonly paired with enalapril for heart disease.
How Enalapril Works in a Dog's Body
ACE inhibitors work by relaxing the arteries and veins to lower blood pressure [1]. They do this by preventing an enzyme in the body from producing angiotensin II, a substance that constricts blood vessels and releases hormones that contribute to high blood pressure [1].
Two effects follow from that. First, blood vessels open up, so the heart does not have to push as hard. Second, ACE inhibitors can increase blood flow to the kidneys and decrease the amount of protein being evacuated from the kidneys into the urine [1]. That protein reduction is why the drug helps dogs with protein-losing kidney disease.
Research in dogs shows these effects are dose related. In a study of healthy Beagles, a higher dose of an ACE inhibitor reduced blood pressure and left ventricular dimensions, which indicates reduced preload and afterload on the heart [3]. The same study found enhanced parasympathetic (rest and digest) nervous system activity at the higher dose [3]. In plain terms, the drug eases the workload on the heart and shifts the nervous system toward a calmer state.
Dosing Basics for Dog Owners
Who decides the dose
Your veterinarian does. The dose depends on your dog's weight, the condition being treated, and other medications or health problems. Doses used in clinical research range from 0.5 mg/kg given twice daily in dogs with proteinuric chronic kidney disease [4] to higher doses in controlled studies, but your dog's prescription is based on your dog's individual situation, not on a study protocol [3][4].
How it is given
Enalapril is given by mouth, usually as a tablet. Many dogs take it well in a small treat or pill pocket. If your dog is difficult to pill, ask your veterinarian about compounding options before you start crushing tablets on your own.
What to do about a missed dose
If you miss a dose, give it when you remember unless it is almost time for the next one. In that case, skip the missed dose and go back to your regular schedule. Do not give two doses at once. Call your veterinarian if you are unsure or if you miss more than one dose in a row.
Enalapril for Dogs Side Effects: What to Watch For
Most side effects are mild, and many dogs show none at all. The table below separates the signs owners report most often from the ones that need urgent action.
| Side effect | How common or serious | What to do |
|---|---|---|
| Vomiting | Reported with toxic doses and in dogs with underlying disease [1] | One episode with normal energy: monitor and call your vet. Repeated vomiting: call the same day |
| Diarrhea | Reported with toxic doses and in dogs with underlying disease [1] | Mild and brief: monitor. Ongoing or with blood: call your vet |
| Lethargy or weakness | Reported with toxic doses and in dogs with underlying disease [1] | Mild tiredness for a day or two can be an adjustment. Lasting lethargy or collapse: call now |
| Low blood pressure (hypotension) | A known risk of ACE inhibitors and of overdose [1] | Weakness, wobbliness, pale gums, or fainting: emergency visit |
| Rising kidney values | A recognized risk that is why rechecks are scheduled [2] | No visible signs at first. Keep the 1 to 2 week recheck appointment [2] |
| Reduced appetite | Often tied to nausea or low blood pressure | If your dog skips two meals, call your vet |
Enalapril dog vomiting
Vomiting is one of the signs reported when dogs ingest too much enalapril, and it is more likely in pets with underlying medical problems such as kidney failure or heart disease [1]. That does not mean every vomit is an emergency. A single episode in a dog who is otherwise bright and eating is worth watching. Vomiting that repeats, comes with diarrhea, or leaves your dog dull and off food deserves a same day call. If your dog is vomiting and also taking other medications, our article on antibiotic side effects in dogs explains how to sort out which drug is the likely cause.
Enalapril dog lethargy
Some dogs are a little quieter for the first day or two as their blood pressure adjusts. True lethargy is different. A lethargic dog is hard to rouse, does not greet you, or will not walk to the food bowl. Lethargy and weakness are listed among the signs of enalapril overdose, and they are more likely to develop in pets with underlying medical problems [1]. If your dog is weak, wobbly, or collapses, treat it as an emergency.
Enalapril dog kidney values
ACE inhibitors have the potential to cause worsening renal function, which is why reevaluation of renal function is recommended 1 to 2 weeks after starting ACE inhibitor therapy [2]. In a study of 156 dogs receiving ACE inhibitors for cardiac disease, proteinuria, or systemic hypertension, researchers looked for a rise in serum creatinine of at least 0.3 mg/dL between the first visit and the first recheck [2]. That is the kind of change your veterinarian is watching for.
Here is the part owners find confusing. A small rise in kidney values does not always mean the drug must stop. Sometimes it means the dose needs adjusting, sometimes it means the dog needs more fluids or a different medication, and sometimes the values stabilize on their own. Your veterinarian will interpret the numbers alongside your dog's exam, urine tests, and clinical signs. Do not skip the recheck because your dog seems fine. Kidney changes often produce no visible signs at first.
ACE inhibitor dog side effects beyond enalapril
All ACE inhibitors share a similar side effect profile because they work the same way. Low blood pressure is a recognized concern with this drug class, and blood pressure monitoring matters, especially under anesthesia [1][5]. If your dog is scheduled for any procedure, tell the team about every medication your dog takes, including enalapril.
Who Should Not Take Enalapril and What Interacts With It
Dogs with certain conditions may not be good candidates for enalapril, or may need extra monitoring. These include dogs with dehydration, dogs with low blood pressure, and dogs already on medications that lower blood pressure or affect kidney function. Your veterinarian will weigh the risks and benefits for your dog's specific situation.
Drug interactions matter with this medication. Tell your veterinarian about everything your dog receives, including:
- Other blood pressure medications
- Diuretics (water pills)
- Nonsteroidal anti-inflammatory drugs (NSAIDs) for pain
- Steroids, including injectable forms
- Potassium supplements
- Any supplement or over-the-counter product, even if it seems harmless
If your dog recently received a steroid injection, mention it. Our article on steroid injection side effects in dogs explains why those effects can overlap with what you might see on enalapril.
Never start a new medication or supplement without checking with your veterinarian first. The combination matters as much as each drug on its own.
Overdose: When to Call Poison Control or an Emergency Vet
Consumption of toxic amounts of enalapril can result in hypotension (low blood pressure), lethargy, weakness, vomiting, and diarrhea [1]. These clinical signs are more likely to develop in pets with underlying medical problems such as kidney failure or heart disease [1].
If you think your dog ate too many tablets, do not wait for signs to appear. Call for help right away. Have the bottle with you so you can tell the team the strength of the tablets and how many might be missing.
Call your veterinarian or an emergency clinic immediately if your dog:
- Collapsed or fainted
- Has pale or white gums
- Is too weak to stand
- Is vomiting repeatedly
- Has a slow or hard to find pulse
If your regular veterinarian is closed, contact an emergency hospital or a pet poison hotline. Keep those numbers saved in your phone before you ever need them.
Limitations and When to Contact a Veterinarian
This article cannot tell you whether your dog's specific symptoms are from enalapril, from the underlying disease, or from something else entirely. Only your veterinarian can examine your dog, review the lab work, and make that call. Individual cases need individual veterinary judgment.
Use these timing guidelines:
Call now or go to an emergency clinic: collapse, fainting, pale gums, repeated vomiting, severe weakness, trouble breathing, or a suspected overdose [1].
Call the same day: vomiting more than once, diarrhea that continues, refusing food for more than one meal, or unusual dullness that lasts more than a day.
Call within a day or two: mild tiredness that is improving, a single soft stool, or a slightly reduced appetite in a dog who is otherwise acting normally.
Keep routine appointments: the 1 to 2 week kidney recheck after starting an ACE inhibitor is not optional [2]. Bring a list of everything your dog is taking and note any changes you have seen at home.
Frequently Asked Questions
How long do enalapril side effects last in dogs?
Mild adjustment signs such as slight tiredness often settle within a few days. Vomiting, weakness, or ongoing lethargy are not normal adjustment and should be reported to your veterinarian. If signs persist or worsen, your dog needs an exam and possibly blood work.
Can I stop giving enalapril if my dog seems fine?
No. Do not stop or change the dose without talking to your veterinarian first. Many dogs with heart or kidney disease look normal precisely because the medication is working. Stopping suddenly can let blood pressure and heart workload rise again.
Does enalapril make dogs drink more or urinate more?
Enalapril itself is not a diuretic, so a large increase in drinking or urination is not a typical effect. If your dog suddenly drinks much more, that can point to another problem and should be checked. Keep track of how much water your dog drinks so you can report a clear number.
Is enalapril safe to give with other heart medications?
Many dogs take enalapril alongside other cardiac drugs, and veterinarians prescribe these combinations regularly. The safety depends on which drugs, what doses, and how your dog responds. Always tell your veterinarian about every medication and supplement your dog receives.
What should I ask my veterinarian at the first recheck?
Ask what your dog's kidney values were before treatment and what they are now, whether the change is acceptable, and whether the dose should stay the same. Ask when the next recheck is due and what signs should prompt a call sooner. Write the answers down so you can refer back to them.
Related Articles
- What Are the Side Effects of Gabapentin for Dogs?
- What Are the Side Effects of Vetmedin for Dogs?
- What Are the Side Effects of Antibiotics in Dogs?
- What Are the Side Effects of Trazodone for Dogs?
- What Are the Side Effects of Steroid Injections for Dogs?
- What Are the Side Effects of Seizure Medication in Dogs?
- Benazepril for Dogs: Side Effects, Dosage and Monitoring
- Enalapril for Dogs With Heart Murmur or Heart Failure
- Enalapril or Benazepril for Dogs With Kidney Disease
References
- What is Enalapril?. Pet Poison Helpline.
- Retrospective evaluation of risk factors for worsening renal function after angiotensin-converting enzyme inhibitor treatment in dogs. Journal of veterinary internal medicine, 2025.
- Effects of high-dose alacepril on the renin-angiotensin-aldosterone system and autonomic nervous system function in healthy dogs. Veterinary research communications, 2025.
- Characterization of the circulating markers of the renin-angiotensin-aldosterone system in telmisartan- or enalapril-treated dogs with proteinuric chronic kidney disease. Journal of veterinary internal medicine, 2024.
- Risk factors for hypotension in anaesthetized dogs: a retrospective analysis of 390 cases. Frontiers in veterinary science, 2026.