Page 583 - Cote clinical veterinary advisor dogs and cats 4th

Dilated Cardiomyopathy 265

Acute General Treatment ○ Spironolactone 1-2 mg/kg PO q 12h ○ Dogs: 110 mg/kg PO q 12h in boxers
and American cocker spaniels
Goal is to alleviate overt clinical signs and/or ■ Start at recheck if tolerating other • Appetite stimulants: prn
VetBooks.ir Symptomatic: ○ Beta-blockers are contraindicated in CHF ○ Dogs: mirtazapine 0.6 mg/kg PO q 24h; Diseases and Disorders
medications
control life-threatening arrhythmias.
and not recommended
• CHF (p. 408)
cyproheptadine 0.2 mg/kg PO q 24h; or
○ Oxygen supplementation (p. 1146)
capromorelin 3 mg/kg PO q 24h
○ Furosemide 2-4 mg/kg IV or IM bolus ○ Potassium supplementation prn ○ Cats: mirtazapine 3.75 mg/CAT PO q 72h
2 mEq per 4.5 kg PO q 12h
■
for severe distress, additional boluses prn Arrhythmias: or cyproheptadine 2 mg/CAT q 12h
Authors’ bolus 2 mg/kg IV q 1-2h until • Ventricular
■
respiratory rate has decreased by half ○ Holter or ECG: treatment with ven- Behavior/Exercise
of initial presentation or until < 40 tricular antiarrhythmic agents does not • Absolute rest during treatment of CHF or
breaths/min reduce the risk of fatal arrhythmias, life-threatening arrhythmias
Cats: 1-2 mg/kg IV bolus, followed by and these agents may be proarrhythmic. • After CHF is resolved, slowly increase activity
■
1 mg/kg boluses q 2-6h; cats do not However, treatment is generally recom- to normal levels.
tolerate high doses of diuretic therapy mended if couplets, triplets, paroxysms/ • Always allow patient to take breaks or stop
○ Pimobendan 0.2-0.3 mg/kg PO q 8-12h bursts/salvos, or runs of ventricular exercising when tired.
in hospital tachycardia are very closely coupled
○ Minimize stress: sedation prn (e.g., R on T). Drug Interactions
Butorphanol 0.2-0.4 mg/kg IV or IM ○ Chronic medical management • Dobutamine and furosemide precipitate
■
Acepromazine 0.005 mg/kg IV or IM, Sotalol 1-2 mg/kg PO q12h (authors’ (requires two catheters)
■ ■
only if systolic BP > 100 mm Hg preference) • Amiodarone will increase serum digoxin levels
○ Dobutamine: fulminant CHF or cardio- ■ Mexiletine 4-8 mg/kg PO q 8h (may • Hypokalemia, hypercalcemia, renal dysfunc-
genic shock be combined with sotalol prn) tion, and hypothyroidism will predispose to
Monitoring: ECG for arrhythmias and Amiodarone 10-20 mg/kg PO q 24h for digitalis intoxication (reduce dose of digoxin)
■ ■
BP for systemic hypertension 7-10 days, then reduce to 3-15 mg/kg
Dogs: 2.5-15 mcg/kg/min PO q 24-48h (for refractory arrhyth- Possible Complications
■
○ Increase by 2.5 mcg/kg/min increments q mias, discontinue sotalol) • Renal insufficiency due to low cardiac output
15-30 minutes to effect. If VPCs noted or • Supraventricular (e.g., atrial fibrillation, and/or overzealous diuresis
heart rate (HR) increases > 10%, decrease flutter, or supraventricular tachycardia) • Mild to moderate azotemia often occurs with
to previous rate. ○ Treatment is aimed at HR control. diuretic therapy.
Cats: 1-10 mcg/kg/min. Use with ○ HR > 160 beats/min in hospital ○ Ensure patient is on lowest diuretic dose
■
caution because may cause seizures ■ Goal of treatment: HR < 160 beats/ that controls CHF.
○ Effusion min in hospital ○ Consider reducing ACE inhibitor dose.
Prompt thoracocentesis (p. 1164) Diltiazem XR (12-hour release formula- ○ Mild azotemia is tolerable if patient
■ ■
and/or abdominocentesis (p. 1056) tion) 2-4 mg/kg PO q 12h (authors’ clinically normal
indicated for large volume effusions preference) • Sudden death due to arrhythmias
to alleviate patient discomfort ■ Digoxin 0.001-0.005 mg/kg PO q 12h
• Arrhythmias: acute treatment indicated for (0.003 mg/kg PO q 12h is authors’ Recommended Monitoring
life-threatening and hemodynamically signifi- preference); combined with diltiazem • Renal/electrolyte panel 5-7 days after starting
cant arrhythmias (pp. 94, 96, and 1033) if HR not adequately controlled or changing medications (diuretics, ACE
■ Amiodarone 10-20 mg/kg PO q 24h for inhibitors)
Chronic Treatment 7-10 days, then reduce to 3-15 mg/kg • Thoracic radiographs, ECG, BP, depending
Goal is to alleviate clinical signs while avoiding PO q 24-48h; combined with diltiazem on clinical exam
iatrogenic side effects from medications. If a if HR not adequately controlled • Holter monitor: 1-4 weeks after starting or
patient is tolerating medications, the authors ○ Cardioversion not routinely performed in adjusting antiarrhythmic medication
do not recommend dose reduction, with the CHF patients • Echocardiography: if significant or unex-
exception of using the lowest dose of diuretics pected change in patient’s condition
(i.e., furosemide) that controls clinical signs. Nutrition/Diet • Serum digoxin level: 1 week after starting
Asymptomatic: Diet changes should be implemented after CHF therapy, 6-8 hours after pill
• Echocardiogram is controlled: ○ Therapeutic range: 0.8-1.8 ng/mL
○ Normal indices: no treatment • Diet should not be changed at expense of
○ Evidence of systolic dysfunction (the patient appetite. PROGNOSIS & OUTCOME
PROTECT study demonstrated that • Ensure adequate protein intake.
pimobendan prolonged the time to onset • Avoid grain-free boutique diets. • Asymptomatic (occult DCM): pimobendan
of clinical signs and extended survival in • Eliminate high-sodium treats. significantly prolongs the onset of clinical
Dobermans with occult DCM) ○ Sodium-restricted commercial diets (Royal signs.
Pimobendan 0.2-0.25 mg/kg PO q 12h Canin Early Cardiac, Hill’s g/d or h/d) ○ Doberman pinschers and Irish wolfhounds
■
• Holter or ECG: see Arrhythmias section or balanced home-cooked meals ○ Effect in other breeds and cats has not
below and other sources (pp. 94, 96, and • Omega-3 fatty acids may improve appetite been evaluated at this stage.
1033) and reduce cardiac cachexia • Symptomatic (CHF or syncope)
Symptomatic: ○ Dog: eicosapentaenoic acid (EPA) 40 mg/ ○ Pimobendan, furosemide, and an ACE
• CHF (p. 409) kg PO q 24h and docosahexaenoic acid inhibitor confer the best long-term
○ Lasix 2 mg/kg PO q 12h (DHA) 25 mg/kg PO q 24h prognosis.
○ Pimobendan 0.2-0.25 mg/kg PO q 12h When indicated on a case by case basis: ○ Prognosis is influenced by response to
○ Angiotensin-converting enzyme (ACE) • Taurine supplementation treatment, underlying cause, owner
inhibitor 0.25-0.5 mg/kg PO q 12h ○ Cats: 250 mg/CAT PO q 12h compliance, and tolerance of medications.
Delay starting if patient anorexic or ○ Dogs: 500 mg/DOG PO q 12h ○ Atrial fibrillation confers a shorter median
■
azotemic • L-carnitine supplementation survival time.
www.ExpertConsult.com