Page 160 - Problem-Based Feline Medicine

152 PART 3 CAT WITH SIGNS OF HEART DISEASE

pleural effusion may be present. Pleural effusion is Treatment of the symptomatic cat with congestive
more common in dilated cardiomyopathy than in other heart failure (acute management).
forms of cardiomyopathy. The fluid may be a transu- Criteria to start therapy:
date, modified transudate or chylous. ● Respiratory distress (open-mouth breathing or very
abnormal respiratory pattern).
Electrocardiographic findings ● Pulmonary congestion (moderate to severe) on radi-
Ventricular arrhythmias are present in about 50% of ographs and/or pleural effusion.
cases. ● Hypothermia.
● Oxygen.
Tachycardia, ventricular conduction disturbances ● Diuretics.
(notched QRS), or tall R waves on lead II (> 0.9 mV) – Furosemide 1–2 mg/kg IV or IM q 8–12 h until
are commonly found. respiratory rate and pattern are normalized.

Atrial fibrillation is more common than in HCM and – Furosemide constant rate infusion (if normal renal
is usually associated with extreme dilatation of the left values at presentation) 0.5–1 mg/kg/hr until con-
and/or right atria. gestion is resolved but not for longer than 24 hours.
● Venodilator.
Echocardiographic findings – Nitroglycerin ointment (2%) 1/4 of an inch (6
mm) q 8 h.
The echocardiographic findings reveal severe biventric-
● Inotropic support.
ular dilatation with severe biatrial enlargement. The
– Dobutamine continuous rate infusion, IV 1–3
left atrial to aortic ratio is usually >2.0.
μg/kg/min (watch for vomiting or seizures). OR
Left ventricular systolic function is markedly dimin- – Pimobendan 0.25 mg/kg PO q 12 h (only if able
ished (fractional shortening is less then 20–25% in most to pill without causing distress)
cases). Normal FS is between 35–55%. ● Thoracocentesis (right thorax to avoid puncturing
of the enlarged auricles) if there is evidence of moder-
Left ventricular internal dimensions in diastole is
ate to severe pleural effusion on radiographs.
usually larger than 20 mm. Intracardiac thrombi may
● Angiotensin-converting enzyme inhibitor (see
be found. Normal LV end-diastolic dimension is up to
above).
17 mm.
● Taurine supplement (see above).
In taurine-deficient cats, improvement in chamber ● Thermoregulatory support (heating blanket).
size and contractility is seen 6–8 weeks after starting – Fluid therapy should be done cautiously until
supplementation. stable cardiac function is established.

Laboratory findings Symptomatic cat with congestive heart failure (chronic
Plasma taurine levels (heparinized sample) are less than management).
30 nmol/ml in most cats. Plasma levels of 40–60 Criteria to start therapy:
nmol/ml may be consistent with taurine deficiency. ● Maintenance therapy after initial treatment for
acute congestive heart failure.
Cats with congestive heart failure may show azotemia ● Any patient found to have early evidence of con-
due to decreased renal perfusion. gestive heart failure (usually on radiographs) but
without symptoms, that will require acute interven-
tion if untreated.
Treatment
– Diuretics
Treatment of the asymptomatic cat: – Furosemide 0.5–1.0 mg/kg PO q 12–24 h OR
● Angiotensin-converting enzyme inhibitors – Hydrochlorothiazide 1–2 mg/kg PO q 12 h
– Enalapril 0.25–0.5 mg/kg PO q 24 h OR OR/AND
– Benazepril 0.25–0.5 mg/kg PO q 24 h. – Spironolactone 2–4 mg/kg PO q 12 h.
● Nutraceuticals ● Angiotensin-converting enzyme inhibitor (see above)
– Taurine PO 250–500 mg q 12 h. ● Taurine supplement (see above)