Page 305 - Clinical Small Animal Internal Medicine

27 Feline Myocardial Disease 273

(butorphanol 0.3 mg/kg, IM or SC) for cats in distress. such as an ACEI and spironolactone. Cats that have
VetBooks.ir Initially, furosemide should be given IV at 2 mg/kg, but experienced an episode of CHF are likely to be at risk of
ATE, so should also receive antiplatelet treatment.
may be given IM until IV access can be secured.
Repeated doses are given every 30–60 minutes, to
of ATE (18.75 mg per cat q24h PO), as aspirin (at either
effect. Response is assessed by monitoring respiratory Clopidogrel is the first‐choice treatment for prevention
rate and effort, with the goal of returning respiratory 5 mg/kg or 75 mg q72h) does not appear to be as effec-
rates to normal (or at least <40 breaths/min). Renal tive, though is well tolerated.
function and electrolytes should also be monitored, as Administering multiple medications is a problem with
hypokalemia and elevations in BUN are common. many cats, so combining tablets in a single gelatine
Although the effect of therapy on renal function and capsule can be helpful.
electrolytes should be considered, the principal goal
should be the elimination of congestive signs.
Intravenous fluids should be avoided in the presence of Asymptomatic Cats
congestive heart failure, even in hypotensive cats (sys- Low‐Risk Cats
tolic blood pressure <100 mmHg). For hypothermic, Many asymptomatic cats will have normal survival
hypotensive cats without a heart murmur, pimobendan times whether or not they receive treatment. It is debat-
(1.25 mg PO per cat) can be considered. able whether extending survival is possible in low‐risk
Hospitalized cats are often stressed, and once respira-
tory distress is controlled they may benefit from being cats, although improving quality of life might be a
worthwhile aim. In human HCM patients, LV outflow
returned to their home environment. tract obstruction can be associated with chest pain and
Cats with “transient myocardial thickening” (TMT)
warrant a specific mention, as they have a better than exertional dyspnea, which can be relieved with atenolol
in some patients. Although atenolol does not seem to
expected prognosis. The cause of TMT is unknown, but confer an obvious survival benefit in cats with HCM
affected cats are often young and have a history of a and LV outflow tract obstruction, there are anecdotal
recent stressful event. They usually present with CHF reports that atenolol might improve activity levels in
associated with thickened LV walls, but if treated appro- some cats.
priately for their heart failure can make a full recovery,
with return to a normal cardiac phenotype. High‐Risk Cats
For outpatient management, parenteral furosemide
can be replaced with oral furosemide. The goal of There are currently no therapies that are known to
reduce the risk of developing CHF in cats with myocar-
long‐term management is to maintain control of con- dial disease, apart from treating hyperthyroidism, hyper-
gestive signs and to prevent ATE. Evidence‐based tension, and anemia when present. As high‐risk cats
selection of therapeutic agents for CHF management are at risk of ATE, they should receive antiplatelet
in cats suffers from the absence of clinical trial data. treatment.
Angiotensin converting enzyme inhibitors (ACEI),
spironolactone, and pimobendan are all currently
used off‐label in the treatment of CHF in cats. ACEIs
have not been associated with any adverse effects in Prognosis
cats with cardiac disease and in theory should
counteract furosemide‐mediated activation of the Feline myocardial disease has a very varied prognosis,
renin‐angiotensin‐aldosterone system (RAAS). ranging from a benign condition with minimal influence
Spironolactone should also act on the RAAS and has on morbidity and mortality in many cats, to a disabling
been reported to have favorable effects in experimen- and potentially fatal condition associated with respira-
tal models of HCM, but its use was reported to result tory distress, sudden death, and pain and paralysis.
in skin lesions in a small minority of cats. Pimobendan Factors such as gallop sounds, arrhythmias, LA enlarge-
is considered contraindicated in cats with HCM and ment, and systolic dysfunction are indicators of a poor
outflow tract obstruction, but is a logical choice for prognosis and high risk of cardiac complications, and
treatment of cats with systolic dysfunction. Diltiazem absence of these factors is likely to indicate a more benign
is rarely used, and beta‐adrenergic antagonists such as outcome. Of these factors, LA enlargement is the most
atenolol are generally considered contraindicated in important predictor and the ability to assess LA size with
the presence of congestive heart failure. echocardiography is extremely useful. By focusing on
Cats with recurrent or persistent CHF despite appro- potential risk, the complex issues of cardiomyopathy
priate doses of diuretics are generally managed by classification are avoided and therapy can be directed at
increasing diuretic doses and adding medications cats that are in most need.