Page 90 - Small Animal Internal Medicine, 6th Edition

62 PART I Cardiovascular System Disorders

BOX 3.1
VetBooks.ir Acute Treatment of Decompensated Congestive Heart Failure

Minimize patient stress and excitement!
Cage rest; transport on gurney (no activity allowed) arterial pressure is 90-110 mm Hg), then q12h; or
cautious IV bolus at 0.05-0.1 mg/kg, repeat q1-2h
Avoid excessive heat and humidity if needed; or
Improve oxygenation: (Less useful as acute therapy [and avoid concurrent
Ensure airway patency nitroprusside]: ACE inhibitor; or amlodipine [dogs:
Give supplemental O 2 (avoid > 50% for > 24 hours) 0.05-0.1 mg/kg initially, to 0.3 mg/kg PO q12-
Postural support if needed (help maintain sternal 24h]; see text)
recumbency, head elevation) ±Additional inotropic support (if myocardial failure or
If frothing evident, suction airways persistent hypotension):
Intubate and mechanically ventilate if necessary Dobutamine* (1 µg/kg/minute initial CRI; titrate
Thoracocentesis, if moderate or severe pleural effusion upward to effect q15-30 min, as needed; dogs: up
suspected/documented to 20 µg/kg/min; cats: up to 10 µg/kg/min) for
Diuresis 24-48 hours then wean down. Alternatively, can use
Furosemide (dogs: 2-3[-5] mg/kg initial bolus, IV (or IM dopamine** (dogs: 1-10 µg/kg/min CRI; cats:
or SC), then 1-4 mg/kg q1-4h until respiratory rate 1-5 µg/kg/min CRI; start low, titrate to effect
decreases, then 1-4 mg/kg q6-12h; or use q15-30 min) for 24-48 hours then wean down;
0.6-1 mg/kg/h CRI over next 6 hours if inadequate and/or
response to boluses [see text]; cats: 1-2[-4] mg/kg Amrinone (1-3 mg/kg IV; 10-100 µg/kg/min CRI), or
initial bolus, IV (or IM or SC), then 1-2 mg/kg q1-4h milrinone (50 µg/kg IV over 10 minutes initially;
until respiratory rate decreases, then 1-2 mg/kg 0.375-0.75 µg/kg/min CRI [human dose])
q6-12h) Digoxin (not generally used unless as adjunct for atrial
(Provide access to water after diuresis is evident) fibrillation in dogs) PO (see Table 3.3); (digoxin
Support cardiac pump function (inodilator) loading dose [see text for indications]: PO—1 or 2
Pimobendan (dogs: 0.2-0.3 mg/kg PO q12h, begin as doses at twice calculated maintenance; dog IV
soon as possible; cats: for CHF associated with [NOT advised unless other therapy not effective/
advanced or end-stage cardiomyopathies or reduced available]: 0.0025 mg/kg slow IV bolus, repeat
contractility, dose as for dogs [controversial for hourly over 4-hour period to effect (or total of
first-onset CHF from HCM; not advised for HOCM]) 0.01 mg/kg)
Reduce anxiety: ±Reduce bronchoconstriction:
Butorphanol (dogs: 0.2-0.3 mg/kg IM [or IV, SC], can Aminophylline (dogs: 4-8 mg/kg slow IV, IM, SC, or
repeat in 30-60 min if needed; cats: 0.1-0.3 mg/kg 6-10 mg/kg PO q6-8h; cats: 4-8 mg/kg IM, SC, PO
IM [or IV, SC]); or q8-12h) or similar drug
Morphine (dogs: 0.025-0.1 mg/kg IV boluses q2-3 min Monitor and address abnormalities as possible:
to effect, or 0.1-0.5 mg/kg single IM or SC dose; Respiratory rate, heart rate and rhythm, arterial
do not use in cats); or pressure, O 2 saturation, body weight, urine output,
Buprenorphine (cats: 0.005-0.02 mg/kg IV, IM, SC) hydration, attitude, appetite, serum biochemistry and
±Additional vasodilators: blood gas analyses.
2% Nitroglycerin ointment: dogs: 0.25-1.5 inch For acute CHF from diastolic dysfunction (e.g., cats with
(0.6-3.8 cm) cutaneously q6h for 24-48 hours (can hypertrophic cardiomyopathy):
combine with hydralazine in dogs); cats: 0.25-0.5 General recommendations, O 2 therapy, furosemide,
inch (0.6-1.3 cm) cutaneously q6-8h for 24-48 and sedation, as in the previous text.
hours; or Thoracocentesis, if needed.
Sodium nitroprusside (if able to monitor blood pressure ±Nitroglycerin
closely): 0.5-1 µg/kg/min (initial) CRI in D 5W (for If severe LV outflow obstruction or persistent and rapid
cats, dilute to 100-300 µg/mL). Titrate upward as sinus tachycardia, consider IV esmolol (200-
needed; dogs: to 5(-15) µg/kg/min; cats: to 2(-5) 500 µg/kg IV over 1 minute, followed by
µg/kg/min; until systolic blood pressure 25-200 µg/kg CRI) or diltiazem (0.15-0.25 mg/kg
~90-100 mm Hg (or mean of 70 mm Hg). Protect over 2-3 minutes IV)
from light, and do not give for more than 24 hours; ±Pimobendan (see previous text)
or Monitor and manage abnormalities as possible (see
Hydralazine (for further afterload reduction in dogs with previous text)
MR, if not using nitroprusside); dogs: initial ACE inhibitor (institute after appetite returns)
0.5-1.0 mg/kg PO, repeat in 2-3 hours (until systolic

ACE, Angiotensin-converting enzyme; CRI, constant rate infusion; D 5 W, 5% dextrose in water.
*Dilution of 250 mg dobutamine into 500 mL of D 5 W or lactated Ringer’s solution yields a solution of 500 µg/mL; CRI of 0.6 mL/kg/h
provides 5 µg dobutamine/kg/min.
**Dilution of 40 mg dopamine into 500 mL of D 5W or lactated Ringer’s solution provides a solution of 80 µg/mL; infusion at 0.75 mL/kg/h
provides 1 µg dopamine/kg/min.