Ace Inhibitors in Dogs

ACE inhibitors are prescription medications that help some dogs with heart disease, high blood pressure, and certain kidney problems. The two most commonly used drugs in this group are enalapril and benazepril. In dogs, they are often part of a larger treatment plan rather than a stand-alone medication. Your vet may use them alongside drugs such as pimobendan, diuretics, blood pressure medications, or a kidney-supportive diet, depending on the diagnosis.

These medications are most often discussed when a dog has congestive heart failure, protein in the urine, or systemic hypertension. In heart disease, ACE inhibitors can reduce the workload on the heart by relaxing blood vessels. In kidney disease, they may help lower pressure inside the filtering units of the kidneys and reduce protein loss into the urine. That can make them useful for some dogs with proteinuric chronic kidney disease or glomerular disease.

ACE inhibitors are not right for every dog. They can lower blood pressure too much in some patients, and they can affect kidney values and potassium levels. Dogs that are dehydrated, critically ill, or already dealing with acute kidney injury may need a different plan. That is why your vet will usually recommend bloodwork, urine testing, blood pressure checks, and follow-up monitoring after starting treatment or changing the dose.

ACE inhibitors block the angiotensin-converting enzyme, which is part of the renin-angiotensin-aldosterone system. That system helps control blood pressure, blood vessel tone, and fluid balance. When the enzyme is blocked, the body makes less angiotensin II, a substance that normally tightens blood vessels and promotes sodium and water retention. With less angiotensin II, blood vessels relax and resistance to blood flow drops.

For dogs with heart disease, that effect can reduce afterload and make it easier for the heart to pump blood forward. This is why ACE inhibitors are commonly used in chronic congestive heart failure, especially when mitral valve disease or dilated cardiomyopathy is involved. They do not cure heart disease, but they may support circulation and help as part of a broader long-term plan.

For dogs with kidney disease, the benefit is a little different. ACE inhibitors can reduce pressure within the glomeruli, the tiny filters inside the kidneys. Lower glomerular pressure may reduce protein leakage into the urine, which is why these drugs are often used in dogs with proteinuria. Your vet may choose enalapril or benazepril based on your dog’s diagnosis, kidney values, blood pressure, and response to treatment.

Many dogs tolerate ACE inhibitors well, but side effects can happen. The most common concerns are low blood pressure, decreased appetite, vomiting, diarrhea, weakness, and lethargy. Some dogs also show changes in thirst or urination. Because these medications can affect kidney blood flow, your vet may recheck kidney values and electrolytes after starting the drug or increasing the dose.

More serious problems are less common but matter. A dog that becomes very weak, collapses, seems unusually sleepy, stops eating, or has a sudden change in water intake or urine output should be checked promptly. These signs can point to hypotension, worsening kidney function, or another medication-related problem. Dogs taking other heart or blood pressure medications may be at higher risk for these issues.

See your vet immediately if your dog collapses, cannot stand, has severe vomiting, seems disoriented, or may have gotten an overdose. Overdoses can cause marked drops in blood pressure and kidney injury. It is also important to tell your vet if your dog is dehydrated, has had recent vomiting or diarrhea, or is not drinking normally, because those factors can change how safely an ACE inhibitor can be used.

ACE inhibitor dosing in dogs varies by drug, body weight, diagnosis, and how the individual dog responds. Merck Veterinary Manual lists a typical dosage range for enalapril and benazepril in dogs of 0.25 to 0.5 mg/kg by mouth every 12 to 24 hours for congestive heart failure. Some dogs are dosed once daily, while others need twice-daily treatment when more continuous ACE inhibition is desired. Your vet will decide what schedule fits your dog’s condition and monitoring results.

These medications are usually given by mouth as tablets or a liquid. They may be given with or without food, though giving with food can help some dogs with stomach upset. PetMD also notes that high-salt treats should be avoided when giving these medications, and dogs should have access to water unless your vet has given different instructions. If your dog misses a dose, contact your vet for guidance. In most cases, you should not double the next dose.

Do not change the dose, stop the medication, or switch between enalapril and benazepril without veterinary guidance. Follow-up care matters as much as the prescription itself. Your vet may recommend rechecking blood pressure, kidney values, electrolytes, and urine protein after starting therapy. That monitoring helps your vet balance benefit, side effects, and long-term safety.

ACE inhibitors can interact with several other medications, so your vet should review everything your dog takes, including supplements. Important interaction groups include diuretics, other blood pressure medications, angiotensin receptor blockers, NSAIDs, corticosteroids, and potassium-sparing drugs such as spironolactone. Some combinations are used intentionally, but they may require closer monitoring because they can increase the risk of low blood pressure, kidney changes, or electrolyte problems.

One common example is the combination of an ACE inhibitor with a diuretic in dogs with congestive heart failure. This can be very appropriate, but it may also increase the chance of dehydration or azotemia if the dog is not drinking well or the doses need adjustment. Merck also notes that hyperkalemia can be worsened when potassium-sparing diuretics are used with an ACE inhibitor, especially if furosemide is not part of the plan.

NSAIDs deserve special attention. In some dogs, combining an ACE inhibitor with an NSAID can reduce kidney perfusion and raise the risk of kidney injury, especially if the dog is dehydrated or has preexisting kidney disease. Always tell your vet about pain medications, supplements, and any human medications in the home. Never start or stop another drug without checking first.