# ACE Inhibitors for Cats: Heart and Kidney Uses ACE inhibitors for cats are prescription medications that block a hormone system driving high blood pressure and fluid buildup. Veterinarians prescribe them most often for cats with heart disease or chronic kidney disease, and sometimes for both at once. They do not cure either condition, but they can slow damage and ease the workload on the heart and kidneys. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - ACE inhibitors are used to treat congestive heart failure in cats and to reduce protein loss in cats with chronic kidney disease [1][2]. - Benazepril and enalapril are the two ACE inhibitors most often prescribed for cats in the United States [1][3]. - Your veterinarian calculates the dose from your cat's weight, kidney values, and heart diagnosis. Never adjust it yourself. - Routine blood work and blood pressure checks are expected, especially in the first weeks of treatment and after any dose change [4]. - Most cats tolerate these drugs well, but low blood pressure, rising kidney values, and high potassium are the main problems to watch for [4]. ## What ACE Inhibitors Are and What They Treat in Cats ACE inhibitors are a drug class that has been used in veterinary medicine for decades. They are widely given to treat chronic congestive heart failure in dogs and cats [1]. In cats, they are also commonly prescribed when the kidneys are leaking protein into the urine, which is a hallmark of chronic kidney disease [2]. ### Heart disease and HCM Cats with hypertrophic cardiomyopathy (HCM) and other forms of heart disease often develop congestive heart failure, where fluid collects in or around the lungs. The general goals of heart treatment in cats are to limit damage to the heart muscle, control fluid accumulation, improve circulation, keep the heart rate and rhythm steady, and protect oxygen levels in the blood [3]. ACE inhibitors are one part of that plan, usually alongside other drugs your veterinarian selects based on the specific disease [3]. One large clinical trial looked at benazepril in 151 cats with heart disease of various causes, some with heart failure signs and some without. The study did not find a benefit of benazepril over placebo in delaying treatment failure [5]. That does not mean the drug is useless. It means the evidence for ACE inhibitors in feline heart disease is weaker than it is in dogs, and your veterinarian will weigh that when deciding whether your cat should take one. ### Kidney disease In cats with chronic kidney disease, ACE inhibitors are used mainly to reduce protein in the urine. Treating these cats generally requires daily administration of an antiproteinuric drug, and benazepril is a common choice [2]. Lowering protein loss may help slow the progression of kidney damage, though every cat responds differently. If your cat has kidney disease, diet matters as much as medication. You can read more about feeding choices in [Cat Kidney Diet Foods](/knowledge/veterinary-medicine/nutrition/cat-kidney-diet-foods) and [Cat Kidney Diet Food](/knowledge/veterinary-medicine/nutrition/cat-kidney-diet-food). Some cats also benefit from omega-3 fatty acids, covered in [Omega-3 Fish Oil for Cats: Dose for Skin Kidney and Joints](/knowledge/veterinary-medicine/nutrition/omega-3-fish-oil-for-cats-dose-for-skin-kidney-and-joints). ## How ACE Inhibitors Work in Cats Your cat's body has a hormone system called the renin-angiotensin-aldosterone system, or RAAS. When blood flow to the kidneys drops, or when the heart starts to fail, this system switches on. It narrows blood vessels and tells the body to hold onto sodium and water. In the short term that is a rescue mechanism. In the long term it raises blood pressure, forces the heart to work harder, and pushes protein through the kidney filters. ACE inhibitors block an enzyme in that chain. The result is wider blood vessels, less fluid retention, and lower pressure inside the kidney's filtering units. In cats with kidney disease, this shows up as less protein in the urine [2]. In cats with heart disease, it means less resistance for the heart to pump against. Researchers have also measured a marker called urinary angiotensinogen, which reflects RAAS activity inside the kidney. It was higher in cats with chronic kidney disease than in healthy cats, which supports the idea that this system is actively involved in feline kidney disease [6]. ## Dosing Basics for ACE Inhibitors in Cats ### Who decides the dose Only your veterinarian does. The dose depends on your cat's weight, the specific drug, kidney values, blood pressure, and what other medications your cat takes. Benazepril has been studied in cats at 0.5 to 1.0 mg/kg given by mouth once daily [5]. That range comes from a clinical trial, not a dosing chart for your cat. Your veterinarian may choose a different amount based on your cat's situation. ### How it is given ACE inhibitors for cats are almost always given by mouth, once or twice daily. They come as tablets or as flavored liquids from a compounding pharmacy. Giving the medication with a small amount of food can help with stomach upset and makes the routine easier for both of you. Some cats are hard to pill. A medicated kidney diet containing benazepril has been studied as an alternative. In that research, cats eating the medicated diet had lower overall drug exposure than cats given once-daily tablets, but ACE inhibition was at least equivalent in cats with kidney disease and higher in healthy cats [2]. This is not a standard option in most clinics yet, but it shows why your veterinarian may ask detailed questions about how well your cat eats and how easily you can medicate. ### Missed doses If you miss a dose, give it when you remember unless it is almost time for the next one. Then skip the missed dose and go back to your normal schedule. Never give two doses at once to catch up. If you are unsure, call your veterinarian's office. They would rather answer a quick question than treat an accidental double dose. ## ACE Inhibitor Side Effects in Cats Most cats on ACE inhibitors have no obvious problems. A large review of 400 cats with elevated kidney values and 110 cats with normal kidney values found that benazepril appeared safe across a mixed population. No cats in that review had documented low systolic blood pressure, and while some cats had rises in creatinine or potassium, those increases were not linked to worse survival [4]. That said, side effects do happen. Here is what to watch for. | Side effect | How common or serious | What to do | |---|---|---| | Tiredness, weakness, or wobbliness | Uncommon, can signal low blood pressure | Call your veterinarian the same day | | Vomiting or poor appetite | Uncommon, often mild | Call if it lasts more than a day or your cat stops eating | | Rising creatinine (kidney values) | Can occur, often mild and not a reason to stop therapy by itself [4] | Continue the drug and recheck blood work as scheduled unless your cat seems ill | | High potassium | Possible, found on blood work | No action at home, your veterinarian monitors this with lab tests | | Low blood pressure | Rare in cats, no documented cases in one large review [4] | Seek care right away if your cat collapses or cannot stand | | Increased vomiting during multi-drug treatment | Reported in one cat in a small cancer study [7] | Report any new or worsening vomiting to your veterinarian | A few side effects are serious enough to act on immediately. Collapse, extreme weakness, cold gums, or a cat who will not stand up needs emergency care. These can point to very low blood pressure. ## Who Should Not Take ACE Inhibitors and What Interacts With Them ### Cats who may not be good candidates ACE inhibitors are not right for every cat. Your veterinarian may avoid them or use them with extra caution if your cat has very low blood pressure, has had a severe reaction to an ACE inhibitor before, or is already on multiple drugs that lower blood pressure. Cats who are dehydrated from vomiting or diarrhea may need fluids and a delay in dosing until they are stable. ### Drug interactions to know about Combining an ACE inhibitor with a nonsteroidal anti-inflammatory drug (NSAID) is a known concern in human medicine, especially when a diuretic is also involved. A study in healthy cats looked at benazepril, robenacoxib (an NSAID), and the two together. The combination was well tolerated, with no negative effects on body weight, food intake, or lab values [8]. That is reassuring for short-term use in healthy cats, but it does not erase the risk in a cat who is already dehydrated or has kidney disease. Tell your veterinarian about every drug and supplement your cat takes, including anything you buy without a prescription. If your cat also has diabetes, review [Drug Interactions with Antidiabetic Medications in Dogs and Cats](/knowledge/veterinary-medicine/clinical-pharmacology/drug-interactions-antidiabetic-medications-dogs-cats) so you can ask informed questions at your next visit. ## Overdose and When to Call for Help An overdose of an ACE inhibitor can cause dangerously low blood pressure, weakness, and collapse. If your cat ate extra tablets, do not wait for symptoms. Call your veterinarian right away. If they are closed, call an animal poison control hotline. The ASPCA Animal Poison Control Center is available at (888) 426-4435, and the Pet Poison Helpline is available at (855) 764-7661. Both may charge a consultation fee. Have the medication bottle with you so you can tell them the drug name, the strength, and how many tablets your cat may have eaten. Do not induce vomiting unless a veterinarian tells you to. ## Limitations and When to Contact a Veterinarian ACE inhibitors are not a cure, and they do not work the same way in every cat. The evidence in feline heart disease is mixed, and one large trial found no benefit of benazepril over placebo for delaying treatment failure [5]. In kidney disease, the goal is usually to lower protein in the urine and slow damage, not to reverse it [2]. Your cat's individual case needs a veterinarian who can examine your cat, run lab work, and adjust the plan over time. Call your veterinarian the same day if your cat becomes weak, wobbly, or unusually quiet, vomits more than once, stops eating, or seems to be drinking and urinating much more than usual. Go to an emergency clinic now if your cat collapses, cannot stand, breathes with an open mouth, has cold gums, or has a seizure. Keep routine recheck visits even when your cat seems fine. Blood work and blood pressure checks are how your veterinarian catches rising creatinine or potassium before they become a problem [4]. ## Frequently Asked Questions ### Do ACE inhibitors help cats with kidney disease? They can help by reducing protein loss in the urine, which is one of the main reasons they are prescribed for feline chronic kidney disease [2]. They do not restore damaged kidney tissue. The benefit is in slowing the rate of further injury, and response varies from cat to cat. ### Do ACE inhibitors help cats with HCM? The evidence is weaker in cats than in dogs. A large randomized trial of benazepril in cats with heart disease of various causes found no benefit over placebo in delaying treatment failure [5]. Many veterinarians still prescribe them as part of a broader heart failure plan, but they are not a stand-alone solution. ### What is benazepril for cats? Benazepril is an ACE inhibitor given by mouth, usually once daily, for heart disease and kidney disease in cats [1][2]. It is one of the most commonly prescribed drugs in this class for cats in the United States. Your veterinarian decides the exact dose based on your cat's weight and lab work. ### What is enalapril for cats? Enalapril is another ACE inhibitor in the same drug class, and it is also used to treat congestive heart failure in cats [1][3]. It works the same way as benazepril by blocking the RAAS pathway. Which one your veterinarian picks often comes down to clinic preference, dosing schedule, and how your cat responds. ### What are the most common ACE inhibitor side effects in cats? Tiredness, vomiting, and poor appetite are the ones owners notice most. Blood work changes like rising creatinine or potassium can occur but often do not require stopping the drug [4]. Low blood pressure is rare in cats and was not documented in one large review of over 500 cats [4]. ## Related Articles - [Treatment For Kidney Failure In Older Cats](/knowledge/veterinary-medicine/veterinary-technology/treatment-for-kidney-failure-in-older-cats) - [Omega-3 Fish Oil for Cats: Dose for Skin Kidney and Joints](/knowledge/veterinary-medicine/nutrition/omega-3-fish-oil-for-cats-dose-for-skin-kidney-and-joints) - [Cat Kidney Diet Foods](/knowledge/veterinary-medicine/nutrition/cat-kidney-diet-foods) - [Drug Interactions with Antidiabetic Medications in Dogs and Cats](/knowledge/veterinary-medicine/clinical-pharmacology/drug-interactions-antidiabetic-medications-dogs-cats) - [Cat Kidney Diet Food](/knowledge/veterinary-medicine/nutrition/cat-kidney-diet-food) - [Gabapentin For Cats](/knowledge/veterinary-medicine/clinical-methods/gabapentin-for-cats) - [Enalapril for Cats: Kidney Disease and Heart Use](/knowledge/veterinary-medicine/pet-medication-guide/enalapril-for-cats-dosage) - [Benazepril for Cats: Uses for CKD and HCM](/knowledge/veterinary-medicine/pet-medication-guide/benazepril-for-cats-ckd-hcm) - [Heart Failure in Cats: Medications and Home Care](/knowledge/veterinary-medicine/senior-and-chronic-care/heart-failure-cats-medication) ## References 1. [Angiotensin-converting Enzyme Inhibitors for Use in Animals - Pharmacology](https://www.merckvetmanual.com/pharmacology/systemic-pharmacotherapeutics-of-the-cardiovascular-system/angiotensin-converting-enzyme-inhibitors-for-use-in-animals). Merck Veterinary Manual. 2. [Why incorporating benazepril into a renal diet may improve treatment efficiency and compliance in cats with chronic kidney disease](https://pubmed.ncbi.nlm.nih.gov/42818666/). Frontiers in veterinary science, 2026. 3. [Treatment of Cardiovascular Disease in Cats - Cat Owners](https://www.merckvetmanual.com/cat-owners/heart-and-blood-vessel-disorders-of-cats/treatment-of-cardiovascular-disease-in-cats). Merck Veterinary Manual. 4. [Safety of Benazepril in 400 Azotemic and 110 Non-Azotemic Client-Owned Cats (2001-2012)](https://pubmed.ncbi.nlm.nih.gov/28282231/). Journal of the American Animal Hospital Association, 2017. 5. [Evaluation of benazepril in cats with heart disease in a prospective, randomized, blinded, placebo-controlled clinical trial](https://pubmed.ncbi.nlm.nih.gov/31560137/). Journal of veterinary internal medicine, 2019. 6. [Urinary angiotensinogen indexed to creatinine or protein is higher in cats with surgically induced chronic kidney disease compared to healthy cats](https://pubmed.ncbi.nlm.nih.gov/42660198/). American journal of veterinary research, 2026. 7. [Multimodal Blockade of the Renin-Angiotensin System Is Safe and Is a Potential Cancer Treatment for Cats](https://pubmed.ncbi.nlm.nih.gov/36006326/). Veterinary sciences, 2022. 8. [Effect of benazepril, robenacoxib and their combination on glomerular filtration rate in cats](https://pubmed.ncbi.nlm.nih.gov/27338786/). BMC veterinary research, 2016. ## Further Reading - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information)