Page 283 - Feline Cardiology

290 Section G: Congestive Heart Failure

Anticoagulant therapy used in cats with myocardial failure or refractory heart
failure.
Congestive heart failure is the end result of severe heart
disease and elevated diastolic filling pressures. Most • ACE inhibitors are not used in the acute setting for
cats with heart failure have moderate or severe atrial heart failure treatment and are added when the cat has
dilation, and are at risk for arterial thromboembolism. returned home and is eating and drinking.
Anticoagulant therapy is recommended for cats with
echocardiographic evidence of spontaneous contrast Cats with acute fulminant congestive heart failure are
(e.g., red blood cell aggregation), an intracardiac throm- fragile patients requiring intensive 24-hour care and
bus, or current or previous arterial thromboembolism. careful handling. These patients have moderate to severe
These recommendations are intuitive and are extrapo- dyspnea with exaggerated abdominal excursions and
lated from human medicine, but definitive proof to possibly abducted forelimbs, tachypnea (often respira-
support their benefit in cats is lacking. Therefore, such tory rate > 80 breaths/min), possibly orthopnea, and
treatment should be implemented only when there is often have impaired demeanor and marked lethargy.
acceptance and compliance with medication adminis- Certainly, there are shades of gray in deciding whether
tration and should never replace life-saving therapy with a cat with a less critical level of dyspnea constitutes
furosemide. It is debatable as to when to start anticoagu- the need for hospitalization, and consultation with the
owner regarding their ability to treat and monitor the
Congestive Heart Failure in cats with moderate or severe atrial dilation. Choices outpatient treatment, and the emotional aspects of both
lant therapy in cats without the previous criteria, but the
cat at home, the cost of hospitalization compared to
authors elect to start prophylactic anticoagulant therapy
hospitalizing a pet versus the fear of deterioration at
of anticoagulants include baby aspirin (5–81 mg PO q 3
home is necessary to arrive at the best overall decision.
days), clopidogrel (18.75 mg PO q 24 hr), low molecular
Dyspneic cats may succumb to overzealous handling
weight heparin (LMWH; enoxaparin 1.5 mg/kg SC q
and restraint to obtain diagnostic tests, so minimal
12 hr) or warfarin 0.1–0.2 mg/kg PO q 24 hr titrated to
increase prothrombin time to 1.5–2 times normal (see
in a 24-hour facility equipped with an oxygen cage,
Chapter 20). restraint is required. These patients are ideally managed
intensive cardiovascular monitoring, and critical care
Treatment of Hospitalized Cats with Acute capabilities. However, immediate stabilization of the
Congestive Heart Failure patient is needed prior to referral. The first triage step
Treatment of hospitalized cats with acute congestive in a dyspneic cat is to evaluate whether there is signifi-
heart failure includes the following: cant pleural effusion that can be immediately removed
by thoracocentesis for immediate stabilization. The cat
• Thoracocentesis of moderate or severe (i.e., large can be kept in sternal recumbency and supplemented
volume) pleural effusion is a rapidly life-saving tech- with oxygen if tolerated while a “triage” thoracic ultra-
nique that should not be delayed. sound is done to evaluate presence of significant pleural
• Aggressive diuretic therapy with parenteral furose- effusion and locate the optimal site for thoracocentesis.
mide (2–4 mg/kg IV q 1–4 hours) is the mainstay of If an ultrasound is not available, a dorsoventral thoracic
therapy for acute cardiogenic pulmonary edema. The radiograph with minimal restraint may be attempted to
furosemide dose and frequency should be rapidly assess for severe pleural effusion. However, obtaining a
tapered once there is improvement in the respiratory radiograph should never be a terminal event. If ultra-
status. sound is unavailable and the cat is too unstable for a
• Enriched inspired oxygen (FiO 2 50%) can be admin- radiograph, the last option is “blind” thoracocentesis at
istered with an oxygen cage, which controls tempera- the right 7th intercostal space using a 19 gauge butterfly
ture, humidity, and removes excess carbon dioxide. catheter. A “blind” approach may cause iatrogenic pneu-
• Transdermal nitroglycerin (1/8–1/4 inch (2-5 mm) q mothorax when the underlying cause of the dyspnea is
6 hr ≤2 days; alternatively application and removal not from pleural effusion and should be used sparingly
every 12 hours for 3 days) is a venodilator, whose if at all (E. Côté, personal observation). Postthora-
efficacy is unknown in cats. It may lessen pulmonary cocentesis thoracic radiographs should be obtained to
venous hypertension, thereby decreasing formation of evaluate for abnormalities such as cardiomegaly and
pulmonary edema. pulmonary venous distension, pulmonary edema, medi-
• Dobutamine is a positive inotrope, which may be used astinal mass, or pulmonary mass. A “triage” echocardio-
in cats with myocardial failure or low output heart gram (see above) is useful to confirm that there is severe
failure. Pimobendan is also a positive inotrope as well heart disease as a cause of the pleural effusion and/or
as arteriolar and venous vasodilator, which may be pulmonary edema. Presence of significant left and/or