Congestive heart failure (CHF) is a clinical syndrome resulting from failure of cardiac output to meet the body’s demands at normal filling pressures.1,2 The precise manifestation of CHF depends on the underlying cause. In dogs, left-sided CHF is characterized by pulmonary edema resulting from elevated left-heart filling pressures. Affected dogs typically present with tachypnea and dyspnea. Right-sided CHF is characterized by cavitary effusions and peripheral edema resulting from elevated right-heart filling pressures. In some cases, biventricular failure occurs and signs of left- and right-sided CHF are seen.
When dogs with suspected CHF are treated, the diagnosis should first be confirmed and patient stability should be assessed.1 This can be done through physical examination and additional diagnostic tests, including radiography, point-of-care ultrasonography, and echocardiography.1,2 Patient stability should not be sacrificed to obtain diagnostics. Thoracocentesis or abdominocentesis is recommended to relieve effusions deemed sufficient to impair ventilation.1 If the patient fails to respond to initial stabilization, prioritization of imaging may be warranted to confirm the diagnosis.
Dogs with acute CHF should receive supplemental oxygen in conjunction with parenteral administration of a loop diuretic, such as furosemide.1-3 Acute stabilization is potentially more critical for left-sided CHF, as pulmonary edema will result in dyspnea.2 Some dogs might benefit from low-dose sedatives to mitigate the effects of stress or anxiety on respiratory rate and effort.1,2 Pimobendan is also recommended to help stabilize patients with acute CHF.1-5 Measurement of systemic blood pressure is also helpful and might help guide decisions regarding afterload reduction.2
Once the patient is stable, diuretic administration can be transitioned from parenteral to oral and chronic treatment can begin. The 2019 American College of Veterinary Internal Medicine consensus statement guidelines and various separate studies support the use of diuretics,1,3,6 pimobendan,1,4,5 angiotensin-converting enzyme inhibitors,7-11 and spironolactone8,9,12 to treat dogs with chronic CHF. If arrhythmias are present, antiarrhythmic drugs may be indicated. Serum biochemical and electrolyte measurements can provide additional information, particularly on renal function, and can help guide and optimize individual therapy.1
Regular monitoring of the dog’s condition is crucial. This includes monitoring respiratory rate and effort, especially when reducing the dose of furosemide, and is especially important in patients with left-sided CHF. Dogs receiving chronic CHF therapy should also be routinely monitored for the development of significant azotemia or electrolyte derangements, which might prompt adjustments to therapy.1 Additional diagnostics such as radiography might help confirm or refute resolution of CHF and guide adjustments to therapy.
Once the patient’s clinical status has stabilized and no further adjustments to therapy are necessary, the frequency of diagnostic testing can be reduced. Owners should monitor respiratory rate and effort at home daily, and repeated resting respiratory rates greater than 35 breaths/min or gradual upward trending from the dog’s baseline rates should prompt reassessment.1,13
In certain specific circumstances (e.g., patent ductus arteriosus, valvular pulmonic stenosis, myxomatous mitral valve disease), surgical or minimally invasive interventions might also be considered.14-20
References
1. Keene BW, Atkins CE, Bonagura JD, et al. ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs. J Vet Intern Med. 2019;33(3):1127-1140. doi:10.1111/jvim.15488
2. Swift S. Congestive heart failure in canines. Todays Vet Pract. 2018;8(3):25-34.
3. Adin DB, Benjamin EJ. Standard medical therapies for preclinical heart disease and congestive heart failure in dogs. Todays Vet Pract. 2023;13(5):14-19.
4. Häggström J, Boswood A, O’Grady MR, et al. Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease: the QUEST study. J Vet Intern Med. 2008;22:1124-1135. doi:10.1111/j.1939-1676.2008.0150.x
5. O’Grady MR, Minors SL, O’Sullivan ML, Horne R. Effect of pimobendan on case fatality rate in Doberman pinschers with congestive heart failure caused by dilated cardiomyopathy. J Vet Intern Med. 2008;22(4):897-904. doi:10.1111/j.1939-1676.2008.0116.x
6. Besche B, Blondel T, Guillot E, Garelli-Paar C, Oyama MA. Efficacy of oral torsemide in dogs with degenerative mitral valve disease and new onset congestive heart failure: The CARPODIEM study. J Vet Intern Med. 2020;34(5):1746-1758. doi:10.1111/jvim.15864
7. Sisson DD. Acute and short-term hemodynamic, echocardiographic, and clinical effects of enalapril maleate in dogs with naturally acquired heart failure: Results of the invasive multicenter prospective veterinary evaluation of enalapril study: The IMPROVE study group. J Vet Intern Med. 1995;9(4):234-242. https://doi.org/10.1111/j.1939-1676.1995.tb01074.x
8. Borgarelli M, Ferasin L, Lamb K, et al. Delay of appearance of symptoms of canine degenerative mitral valve disease treated with spironolactone and benazepril: the DELAY study. J Vet Cardiol. 2020;27:34-53. doi:10.1016/j.jvc.2019.12.002
9. Coffman M, Guillot E, Blondel T, et al. Clinical efficacy of a benazepril and spironolactone combination in dogs with congestive heart failure due to myxomatous mitral valve disease: The benazepril spironolactone study (BESST). J Vet Intern Med. 2021;35(4):1673-1687. doi:10.1111/jvim.16155
10. Controlled clinical evaluation of enalapril in dogs with heart failure: Results of the cooperative veterinary enalapril study group The COVE study group. J Vet Intern Med. 1995;9(4):243-252. doi:10.1111/j.1939-1676.1995.tb01075.x
11. Ettinger SJ, Benitz AM, Ericsson GF, et al. Effects of enalapril maleate on survival of dogs with naturally acquired heart failure. JAVMA. 1998;213(11):1573-1577.
12. Bernay F, Bland JM, Häggström J, et al. Efficacy of spironolactone
on survival in dogs with naturally occurring mitral regurgitation caused by myxomatous mitral valve disease. J Vet Intern Med. 2010;24(2):331-341. doi:10.1111/j.1939-1676.2009.0467.x
13. Porciello F, Rishniw M, Ljungvall I, Ferasin L, Haggstrom J, Ohad DG. Sleeping and resting respiratory rates in dogs and cats with medically-controlled left-sided congestive heart failure. Vet J. 2016;207:164-168. doi:10.1016/j.tvjl.2015.08.017
14. Uechi M. Mitral valve repair in dogs. J Vet Cardiol. 2012;14(1):185-192. doi:10.1016/j.jvc.2012.01.004
15. Matsuura K, Yoshida T, Yamada S, et al. The outcome of surgical mitral valve repair with loop-in-loop technique in dogs with different stage myxomatous mitral valve disease. J Vet Cardiol. 2022;42:74-82. doi:10.1016/j.jvc.2022.06.001
16. Nguyenba TP, Tobias AH. The Amplatz canine duct occluder: a novel device for patent ductus arteriosus occlusion. J Vet Cardiol. 2007;9(2):109-117. doi:10.1016/j.jvc.2007.09.002
17. Hulsman AH, Breur JMPJ, Szatmári V. Low profile vascular plug for transarterial occlusion of patent ductus arteriosus in small dogs. J Vet Intern Med. 2021;35(1):98-106. doi:10.1111/jvim.15966
18. Morgan KRS, Stauthammer CD, Barncord K, Pinkos A, Fundingsland S, Rishniw M. Transvenous detachable coiling of patent ductus arteriosus in small dogs. J Vet Cardiol. 2022;42:65-73. doi:10.1016/j.jvc.2022.06.002
19. Borgeat K, Gomart S, Kilkenny E, Chanoit G, Hezzell MJ, Payne JR. Transvalvular pulmonic stent angioplasty: procedural outcomes and complications in 15 dogs with pulmonic stenosis. J Vet Cardiol. 2021;38:1-11. doi:10.1016/j.jvc.2021.09.002
20. Keating S, Eberhard J, Friederich J, Wess G. Systolic function in dogs with pulmonic stenosis of different severities and the effect of balloon valvuloplasty. J Vet Cardiol. 2023;46:40-54. doi:10.1016/j.jvc.2023.03.004