ACVIM Mitral Valve Disease
2019 ACVIM Consensus Guidelines
Classification
A
Dogs at high risk for developing heart disease but have no identifiable structural disorder of the heart
B
Dogs with structural heart disease (murmur), but have not developed clinical signs of heart failure.
B1
Asymptomatic dogs that have no radiographic or echocardiographic evidence of cardiac remodeling
B2
Asymptomatic dogs that have more advanced mitral valve regurgitation have radiographic and echocardiographic findings of left atrial and ventricular enlargement
C
Dogs with either current or past clinical signs of heart failure caused by MMVD. Acute heart failure treated in hospital or heart failure treated as an outpatient
D
Dogs with end-stage MMVD, in which clinical signs of heart failure are refractory to standard treatment
Mitral Valve Disease in Dogs
A
  • Dogs at higher than average risk for developing heart failure but without any apparent structural abnormality (ie, no audible heart murmur) at the time of examination.
  • Small breed dogs, including breeds with known predisposition to develop MMVD (eg, Cavalier King Charles Spaniels, Dachshunds, Miniature, and Toy Poodles) should undergo regular evaluations (yearly auscultation by the family veterinarian) as part of routine health care.
  • No drug treatment or dietary treatment recommended for any patient.
B
  • Dogs in Stage B have a structural abnormality but have never had clinical signs of heart failure
  • Typically is recognized during a screening or routine health examination by auscultation of a heart murmur.
  • Thoracic radiography and Blood pressure measurement is recommended in all patients
  • Echocardiography, performed by an experienced operator, is recommended to definitively identify the cause of the murmur
B1
  • Asymptomatic dogs with mitral valve regurgitation caused by MMVD that is not severe enough to trigger the use of medical treatment
  • No drug or dietary treatment is recommended
  • Re-evaluation by echocardiography is suggested (or radiography if echocardiography is unavailable) in 6-12 months
B2
  • Asymptomatic MMVD severe enough to result in cardiac remodeling (LA and LV enlargement) sufficient to recommend treatment before the onset of clinical signs
    • murmur intensity ≥ 3/6
    • Echocardiographic LA : Ao ratio in the right-sided short axis view in early diastole ≥ 1.6
    • Left ventricular internal diameter in diastole, normalized for body weight (LVIDDN) ≥ 1.7
    • breed-adjusted radiographic vertebral heart score (VHS) > 10.5.
  • Pimobendan is recommended at a dosage of 0.25-0.3 mg/kg PO q12h.
  • Dietary treatment is recommended, including mild dietary sodium restriction.
  • Angiotensin converting enzyme inhibitors (ACEI): For patients in Stage B2 on either initial examination, or in which the LA has increased markedly in size
  • Use of cough suppressants can be useful in occasional patients in advanced Stage B2 when their cough is thought to be the result of pressure from cardiac enlargement
C
  • Stage C dogs have MMVD severe enough to cause clinical signs of heart failure. Stage C includes all dogs with MMVD that have experienced an episode of clinical heart failure and that are not refractory to standard heart failure treatment
  • A clinical database (including thoracic radiographs and an echocardiogram) should be obtained. Additionally, basic laboratory tests should be obtained as soon as practical. Impaired renal function in particular represents an important comorbidity.
C
Hospital Treatment
  • Furosemide 2 mg/kg administered IV or IM, followed by 2 mg/kg IV or IM hourly until the patient's respiratory signs are substantially improved or a total dosage of 8 mg/kg has been reached over 4 hours.
  • Pimobendan, 0.25-0.3 mg/kg administered PO q12h.
  • Oxygen supplementation
  • Mechanical treatments (eg, abdominal paracentesis, thoracentesis) if necessary
  • Sedation-anxiety associated with dyspnea should be treated. Butorphanol 0.2 to 0.25 mg/kg administered IM or IV, combinations of buprenorphine (0.0075-0.01 mg/kg) and acepromazine (0.01-0.03 mg/kg IV, IM, or SC).
  • Provide optimal nursing care
  • Dobutamine (2.5-10 μg/kg/min as a CRI, starting at 2.5 μg/kg/min and increasing the dosage incrementally) may be used in addition to the above treatments to improve the left ventricular function in patients that fail to respond adequately to diuretics, pimobendan, sedation and oxygen. Continuous ECG monitoring is recommended where available during dobutamine infusion
  • Constant IV infusion of sodium nitroprusside at dosages ranging from 1 to 15 μg/kg/min) for up to 48 hours often is useful for lifethreatening, poorly responsive pulmonary edema
  • ACE Inhibitors, enalapril or benazepril, 0.5 mg/kg PO q12h.
  • Nitroglycerin ointment, approximately half an inch paste/10 kg BW, applied to an unhaired or shaved area of skin, can be used for the first 24 to 36 hours of hospitalization
C
Home Treatment
  • Continue PO furosemide administration to effect, commonly at a dosage of 2 mg/kg administered q12h. Some panelists now choose to substitute torsemide for furosemide at 1/10-1/20 or approximately 5% to 10% of the furosemide dosage, or approximately 0.1-0.3 mg/kg q24h for home care in animals in which hospitalized CHF management using furosemide was difficult
  • Measurement of serum creatinine, BUN, and electrolyte concentrations 3-14 days after initiating furosemide
  • Continue or start ACEI (eg, enalapril or benazepril, 0.5 mg/kg PO q12h). Measurement of serum creatinine and electrolyte concentrations 3-14 days after beginning an ACEI
  • Spironolactone (2.0 mg/kg PO q12 - 24 h) is recommended as an adjunct for chronic treatment. (Aldosterone antagonism)
  • Continue pimobendan, 0.25-0.3 mg/kg PO q12h.
  • In cases complicated by atrial fibrillation, diltiazem, often in combination with digoxin, is recommended to control ventricular rate.
D
  • Patients have clinical signs of failure refractory to standard treatment for Stage C heart failure from MMVD
D
Hospital Treatment
  • In the absence of severe renal insufficiency (eg, serum creatinine >3 mg/dL), additional furosemide can be administered to dyspneic patients diagnosed with refractory heart failure as an initial 2 mg/kg IV bolus followed by either additional bolus doses or a furosemide CRI at a dosage of 0.66-1 mg/kg/h, until respiratory distress (rate and effort) has decreased, or for a maximum of 4 hours.
  • Torsemide may be used to treat dogs no longer adequately responsive to furosemide (0.1-0.2 mg/kg q12h-q24h or approximately 5%-10% of the current furosemide dosage to deliver a furosemide-equivalent dose).
  • Cavitary centesis (abdominal paracentesis, thoracentesis), as needed to relieve respiratory distress or discomfort.
  • In patients that can tolerate it, more vigorous afterload reduction (arterial vasodilation) is recommended, with close monitoring of arterial blood pressure. Potentially beneficial PO drugs that decrease afterload in this situation include hydralazine (0.5-2.0 mg/kg PO, starting at a low dosage and titrating to effect as described above with nitroprusside, but with hourly dosage increases or amlodipine (approximately 0.05-0.1 mg/kg PO, also to effect.
  • These drugs are recommended in addition to an ACEI and pimobendan. Vigilance is needed to avoid serious, prolonged hypotension (monitor blood pressure closely, maintaining arterial systolic blood pressure >85 mm Hg, or mean arterial blood pressure >60 mm Hg). Serum creatinine concentration should be reevaluated no more than 24 to 72 hours after initiating these drugs.
D
Home Treatment
  • Furosemide (or torsemide) dosage should be increased as needed to decrease the accumulation of pulmonary edema or body cavity effusions, if not limited by renal dysfunction (indicators of which generally should be monitored 12-48 hours after dosage increases).
  • Torsemide, a potent and longer-acting loop diuretic, may be used to treat dogs no longer adequately responsive to furosemide (torsemide beginning dosage of 0.1-0.2 mg/kg PO, or approximately5%-10% of the current furosemide dosage, up to approximately 0.6 mg/kg, divided q12h if necessary).
  • Spironolactone, if not already started as recommended in Stage C, is indicated for chronic treatment of Stage D patients.
  • Pimobendan dosage is increased to include a third 0.3 mg/kg daily dose (off-label use)
  • Additional afterload reduction, using either amlodipine or hydralazine (see dosages and cautions above)
  • Digoxin, at the same (relatively low) dosages recommended by some panelists for Stage C heart failure with atrial fibrillation
  • Sildenafil (1-2 mg/kg PO q8h) may be useful in the management of patients with clinical signs related to exertion and in management of ascites when there is echocardiographic evidence of moderate to severe pulmonary hypertension. 95 (Class IIa, LOE: weak)
  • Cough suppressants an Bronchodilatorsare recommended to treat chronic, intractable cough
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;1–14. https://doi.org/10.1111/jvim.15488