Canine Mitral Valve Disease: A Case Study

Sponsored by Ceva Animal Health, LLC

Myxomatous mitral valve disease (MMVD) is a common condition in middle-aged and older dogs. Although referral to a veterinary cardiologist offers numerous advantages, this condition can be successfully diagnosed and treated in the general practice setting. Recent medical advances have led to new drug options and an increased emphasis on early intervention.^1,2

Raphael’s Case

Raphael, a 7-year-old, neutered male miniature poodle, was presented for a wellness examination. His owner reported that he was “slowing down” and tiring more quickly on walks. Raphael’s medical history was unremarkable, with the exception of grade 1/4 bilateral medial patellar luxation and mild dental disease. He was current on all recommended preventive care.

On physical examination, Raphael had a grade 3/6 left systolic murmur, with a heart rate of 140 bpm; pulses were strong and synchronous. Mild crackles were noted on pulmonary auscultation, and respiratory rate was 48 breaths per minute. The remainder of his physical examination was unremarkable.

Diagnostic tests were recommended and authorized by the client. CBC, serum chemistry, and urinalysis revealed no significant abnormalities, and blood pressure was within normal limits. Thoracic radiography revealed a vertebral heart score of 12, left atrial enlargement, and a mild perihilar interstitial pattern consistent with pulmonary edema.

Based on physical examination and radiographic findings, Raphael was diagnosed with likely MMVD and congestive heart failure (CHF). MMVD is the most common heart disease in dogs in North America, accounting for 75% of heart disease cases.¹ It has a higher prevalence in small-breed dogs, with up to 85% showing signs of valvular lesions by 13 years of age.¹ Other differential diagnoses that were considered as a potential cause of his murmur/CHF included aortic stenosis and pulmonic stenosis, but these were deemed unlikely given his signalment and history.³ Referral to a veterinary cardiologist was recommended but declined.

Presence of a murmur consistent with MMVD and evidence of CHF indicate stage C MMVD, according to the 2019 ACVIM guidelines,¹ which recommend a quadruple therapy approach for treatment of CHF in dogs that includes furosemide, pimobendan, an ACE inhibitor (enalapril or benazepril), and spironolactone.¹

Based on these guidelines, furosemide, pimobendan, and CARDALIS™ (spironolactone and benazepril hydrochloride) were prescribed, along with a prescription cardiac diet.

Raphael returned for a recheck examination 1 week later, and his owner reported some clinical improvement. Raphael’s murmur persisted, but lung sounds were clear. Heart rate was 130 bpm, respiratory rate was 30 breaths per minute, and serum chemistry profile was within normal limits. Based on these findings, all medications were continued, and regular recheck examinations were recommended to assess his clinical condition, renal function, and serum potassium levels and adjust medications as needed.^1,2

What Is CARDALIS™?

CARDALIS™ contains a combination of spironolactone and benazepril to block the renin-angiotensin-aldosterone system (RAAS).^4,5 Benazepril is a potent ACE inhibitor that stops the conversion of inactive angiotensin I to active angiotensin II,⁵ preventing vasoconstriction and aldosterone production. However, there are alternative pathways of aldosterone production, and an ACE inhibitor alone cannot entirely block aldosterone’s action.⁵ Spironolactone is an aldosterone antagonist that allows for better control of the RAAS cascade while preventing other harmful effects of aldosterone, such as cardiac fibrosis and sympathetic nervous system activation.

A 2021 study of 569 client-owned dogs with ACVIM stage C MMVD and CHF demonstrated that the administration of benazepril, spironolactone, and furosemide is effective, safe, and superior as compared with administration of only benazepril and furosemide.⁶ Combining benazepril and spironolactone was shown to reduce the risk for death or worsening of cardiac disease by 27% at day 360. Side effects were comparable to those observed with benazepril alone and included an increased risk for vomiting, renal insufficiency, and hepatopathy.

CARDALIS™ is palatable and easy to dose. Its chewable, scored tablets can be administered once daily, reducing the frequency of medication administration for many owners. In a field study of 233 dogs dosed daily for 14 days, CARDALIS™ was accepted voluntarily (with or without food) in 87.6% of doses.²

CARDALIS™ should not be used in patients with hypoadrenocorticism, hyperkalemia, hyponatremia, or a known hypersensitivity to ACE inhibitors or spironolactone.²

Conclusion

In 2019, the ACVIM consensus committee published updated guidelines for the diagnosis and treatment of MMVD in dogs, with spironolactone being added to the recommended treatment guidelines for dogs with CHF.¹ As evidenced by Raphael’s case, CARDALIS™ offers the ability for pet owners to easily administer spironolactone along with benazepril, providing half of the recommended quad therapy drug classes in a single, once-daily tablet.

CARDALIS™ trademark is the property of Ceva Santé Animale S.A.