Page 138 - Problem-Based Feline Medicine

130 PART 3 CAT WITH SIGNS OF HEART DISEASE

tion as determined by Doppler study (velocity of Treatment of the asymptomatic cat.
blood flow >2.0 m/s) is seen in the obstructive ● Hypertrophic non-obstructive cardiomyopathy
form. (HCM) – Wall dimensions larger than 6 mm and
normal Doppler LV outflow study (LVOT less
max
than 1.8 m/s).
Differential diagnosis
– Normal left atrial size – no therapy.
Congenital heart disease – Increased left atrial size (>13 mm or LA/Ao >
● A murmur is usually present from birth. Most con- 1.5).
genital murmurs do not change in loudness with – Beta-blocker
alterations of the heart rate. Congenital murmurs Atenolol 12.5 mg/cat PO q 12–24 h.
are usually relatively loud. OR
– Calcium channel blockers:
Dilated cardiomyopathy.
Diltiazem 7.5–15 mg PO q 8 h OR
● Murmurs are usually very soft, and in many cases may
Diltiazem slow release − 60 mg PO daily.
not be present. A gallop rhythm is usually present.
● Hypertrophic obstructive cardiomyopathy
Restrictive cardiomyopathy. (HOCM) with presence of systolic anterior motion
● It is difficult to differentiate from hypertrophic car- of the mitral valve and LV outflow obstruction
diomyopathy on auscultation; many cases have a (LVOT <3.5 m/s).
max
gallop rhythm. – Normal left atrial size – no therapy.
– Increased left atrial size – beta-blocker as
Intra-thoracic masses.
above.
● A murmur may not be present unless there is com-
● Hypertrophic obstructive cardiomyopathy (pres-
pression of the heart by the mass or concurrent unre-
ence of systolic anterior motion of the mitral valve
lated heart disease. Most commonly, dyspnea and
and LV outflow obstruction -LVOT >3.5 m/s).
lethargy are seen. max
– Normal or increased left atrial size – beta-
Feline asthma or chronic bronchitis. blocker as above.
● Unless cardiac disease is also present, most cats do
Treatment of the symptomatic cat with congestive heart
not have a murmur. Cough and increased respiratory
failure (acute management).
rate are common. Symptoms in the cat with feline
Criteria to start therapy:
asthma may be episodic and seasonal.
● Respiratory distress (open-mouth breathing or very
Chylous effusion. abnormal respiratory pattern).
● A murmur may not be present. In most cases, car- ● Pulmonary congestion (moderate to severe) on
diac disease is not present. The most common clin- radiographs and/or pleural effusion.
ical signs are dyspnea, increased respiratory rate ● Hypothermia.
and lethargy. – Oxygen.
– Diuretics
Neurological disease causing collapse or hindlimb
– Furosemide 1–2 mg/kg IV or IM q 6–12 h until
paralysis
respiration rate and pattern are normalized.
Cardiac signs are usually absent, however a full cardiac – Furosemide constant rate infusion (if normal
work-up may be warranted to rule out the presence of renal values at presentation) 0.5–1 mg/kg/hr
silent heart disease. Neurological disease usually is not until congestion is resolved but not for longer
associated with alterations of peripheral systemic per- than 24 hours.
fusion. – Nitroglycerin ointment (2%) 1/4 of an inch
(6 mm) q 8 h until resolution of the congestion.
– Angiotensin-converting enzyme inhibitor.
Treatment
– Enalapril 0.25–0.5 mg/kg q 24 h OR
The treatment recommended depends on the severity of – Benazepril 0.25–0.5 mg/kg q 24 h.
signs and the presence of left ventricular outflow tract – Thoracocentesis if there is evidence of moderate
(LVOT) obstruction. to severe pleural effusion on radiographs.