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76 Arrhythmogenic Right Ventricular Cardiomyopathy, Dog

titrated q 5-7 days to maintain a PT or • Antiplatelet therapy: bleeding complications • Dogs are also susceptible to thromboembolic
international normalized ratio of 1.5 to • Diuretic therapy: volume contraction, disease, but the cause and consequences differ
VetBooks.ir patients are initially anticoagulated with • Vasodilator therapy: hypovolemia, decom- Prevention
2 times upper limit of normal. Ideally,
azotemia
from those of feline saddle thrombus.
pensation of renal function
heparin 150 U/kg SQ q 8h and have a
48-hour heparin-warfarin overlap
○ Warfarin therapy has not been investigated • Fluid therapy: volume overload, CHF • Treatment of associated cardiac disease
• Use of antiplatelet agents in patients at risk
sufficiently to analyze safety or efficacy in Recommended Monitoring for thromboembolic disease
feline patients, or • Frequent physical examination
○ Low-molecular-weight heparin (LMWH) • Daily renal, electrolyte, and coagulation Technician Tips
(e.g., dalteparin 100 IU/kg SQ q 12-24h); profile monitoring during hospitalization • Supportive care and excellent nursing care
LMWH may not be efficacious at these • Continuous ECG (arrhythmias common) is paramount to successful outcome.
doses. during hospitalization • The patient should be kept warm and dry.
• Antiplatelet therapy Monitoring of urination is important, and
○ Clopidogrel (18.75 mg PO/CAT q 24h) PROGNOSIS & OUTCOME bladder expression may be necessary.
has been shown in a prospective, double- • Managing clinician should be alerted of
blind, placebo-controlled trial to be • Guarded prognosis: 33%-50% rate of dis- clinical deterioration suggesting possible
associated with longer survival times after charge from the hospital, high chance of intraabdominal infarction (progressive
an initial thromboembolic event compared repeat thromboembolic episodes lethargy, vomiting).
to aspirin therapy. • Prognosis more favorable for partial or
○ Aspirin (dosages range from 5 mg PO/CAT forelimb emboli (75% rate of discharge from Client Education
every 72 hours to 81 mg/CAT every the hospital) • All cats with cardiac disease are presumed to
48 hours). Typically administered at 20- • Grave prognosis with visceral artery be at risk for thromboembolic complications.
25 mg q 48h. Usually administered to occlusions • Cats with increasing amounts of left atrial
patients who do not tolerate clopidogrel • Body temperature at admission appears to enlargement with spontaneous contrast and/
(vomiting, refusal); sometimes adminis- be positively correlated with prognosis: more or an intracardiac thrombus are at high risk
tered concurrently with clopidogrel favorable if temperature > 98.9°F (37.2°C) for thromboembolism.
• Risk/benefit discussion of preventive
Drug Interactions PEARLS & CONSIDERATIONS measures
Multiple drug interactions reported for warfarin • Patients who have had a thromboembolic
(see drug formularies in Section VI for detailed Comments event are at very high risk for recurrent
list) • Although much anecdotal discussion exists, events.
there have been no studies proving that any • Prognosis should be discussed for short- and
Possible Complications preventive measures decrease the likelihood longer-term outcomes.
• Disease complications: gangrenous necrosis of of suffering a thromboembolic event.
a hindlimb; self-mutilation of the limb; vis- Clopidogrel is the sole agent that has been SUGGESTED READING
ceral occlusions leading to organ infarction, shown to significantly increase long-term Smith SA, et al: Arterial thromboembolism in cats:
organ failure, and death; cardiac arrhythmias; survival of cats who have survived an initial acute crisis in 127 cases (1992-2001) and long-term
repeat thromboembolic episodes thromboembolic event. management with low-dose aspirin in 24 cases. J
• Thrombolytic therapy: hemorrhagic com- • Intermittent claudication (lameness) may Vet Intern Med 17:73-83, 2003.
plications, acute reperfusion syndromes signal that a patient is at high risk for aortic AUTHOR: Nancy J. Laste, DVM, DACVIM
(hyperkalemia, acidosis, death) thromboembolism and should prompt a EDITOR: Meg M Sleeper VMD, DACVIM
• Anticoagulant therapy: bleeding complica- discussion about preventive therapy.
tions

Arrhythmogenic Right Ventricular Cardiomyopathy, Dog Bonus Material Client Education
Online
Sheet

BASIC INFORMATION • The disease usually affects dogs > 3 years of
Synonyms age.
Definition Arrhythmogenic right ventricular cardiomyopa- • Males and females are equally represented.
Adult-onset inherited cardiomyopathy, primarily thy (ARVC), boxer cardiomyopathy, arrhyth-
affecting boxer dogs, is classically characterized mogenic cardiomyopathy (AC), arrhythmogenic GENETICS, BREED PREDISPOSITION
by ventricular arrhythmias. A proportion of right ventricular dysplasia, familial ventricular • Boxer dogs have an identified genetic
dogs experience supraventricular arrhythmias, arrhythmia (FVA) of boxers basis of disease, characterized by an auto-
and rarely some dogs demonstrate chamber Epidemiology somal dominant deletion mutation in the
dilation accompanied by left ventricular (LV) striatin gene with incomplete and age-related
systolic dysfunction. Dogs may have an SPECIES, AGE, SEX penetrance.
asymptomatic life or develop symptomatic • ARVC is an adult-onset familial disease of ○ Approximately 70% of dogs with the
ventricular arrhythmias (syncope, sudden death) boxer dogs. mutation will develop some form of the
or rarely have left-sided or biventricular conges- • Age-related penetrance and expression dic- disease (variable severity).
tive heart failure (if myocardial systolic dysfunc- tates that the disease is more frequent and ○ Those homozygous positive for the striatin
tion is present). more severe with advanced age. mutation may have a more severe form

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