Page 139 - Problem-Based Feline Medicine

9 – THE CAT WITH ABNORMAL HEART SOUNDS AND/OR AN ENLARGED HEART 131

– Aspirate from the right thorax to avoid punctur- [Meq/L]) should receive solutions with 20 mmol/L
ing the enlarged auricles. [Meq/L] added.
– Hypertrophic non-obstructive cardiomyopathy –
In cases of hypokalemia refer to standard guidelines of
use calcium channel blocker OR beta-blockers
therapy. Do not exceed rates of potassium 0.5 mmol/L
as above.
(Meq)/kg/h.
– Hypertrophic obstructive cardiomyopathy – use
beta-blockers as above. Chronic diuretic administration is not required in
some cases. Multiple diuretic therapy can be used for
Symptomatic cat with congestive heart failure (chronic
refractory cases but monitor renal function and hydra-
management).
tion carefully.
Criteria to start therapy:
● Maintenance therapy after initial therapy to control Renal function and electrolytes should be monitored
signs of acute onset of congestive heart failure. in all cats on diuretics and angiotensin-converting
● Any patient found to have early evidence of con- enzyme inhibitor therapy.
gestive heart failure (usually on radiographs) but
Some cats develop anorexia or poor appetite while
without symptoms, that will require acute interven-
taking Diltiazem slow-release preparations.
tion if untreated.
Hypertrophic non-obstructive cardiomyopathy – use Prognosis
calcium channel blocker or beta-blocker as above.
Hypertrophic cardiomyopathy and hypertrophic
Hypertrophic obstructive cardiomyopathy – use beta- obstructive cardiomyopathy ultimately result in con-
blocker as above. gestive heart failure and/or aortic saddle thromboem-
bolism. Sudden death occurs in some cases, usually in
Diuretics:
younger cats less than 3 years old.
● Furosemide 1–2 mg/kg IV or IM q 6–12 h until res-
piration rate and pattern are normalized. Median survival time for cats without congestive heart
● Furosemide constant rate infusion (if normal renal failure is 732 days (over 33% alive after 5 years).
values at presentation) 0.5–1 mg/kg/hr and conges- Median survival for cats with congestive heart failure is
tion is resolved but not for longer than 24 hours. 92 days.
● Hydrochlorothiazide 1–2 mg/kg PO q 12 h
Median survival time for cats with thromboembolism is
OR/AND
61 days.
● Spironolactone 2–4 mg/kg PO q 12 h.
Heart rate less than 200 beats per minute at initial pres-
Angiotensin-converting enzyme inhibitor:
entation is associated with longer survival (1830 days vs
● Enalapril 0.25–0.5 mg/kg q 24 h OR
152 days).
● Benazepril 0.25–0.5 mg/kg q 24 h.
Diuretics should be used cautiously in cats. Overzealous
HYPERTHYROID HEART DISEASE***
therapy for 1–2 days may rapidly result in severe fluid and
electrolyte imbalances and metabolic alkalosis.
Classical signs
Judicious concurrent administration of low-sodium
● Weight loss.
solutions (NaCl concentration ≤ 0.45%) with potassium
● Polyphagia.
supplementation may be required in some cases that are
● Heart murmur.
clinically dehydrated after diuretic therapy.
● Tachycardia.
The volume of fluid administered varies with the
degree of dehydration present, but in severe cases rates See main reference page 304 (The Cat With Weight
up to twice maintenance can be infused. While infusing Loss and a Good Appetite).
fluids in a cardiac patient, special attention to respira-
tory function is recommended. Clinical signs
Potassium supplementation should be based on serum Cats are usually older than 8 years of age (mean age is
levels. Patients with normal potassium (3.5–5.5 mmol/L 13 years old) with no breed or sex predilection.