Page 224 - Clinical Small Animal Internal Medicine

192 Section 3 Cardiovascular Disease

some cardiac therapies such as diuretics or spironol- dog with apparent DCM diagnosed in a breed other than
VetBooks.ir actone. During administration, renal function is moni- the “typical” breeds (i.e., Doberman pinscher, Great
Dane, boxer, mastiff, or Irish wolfhound) known for this
tored and pet owners are instructed about possible
gastrointestinal side‐effects. Chronic monitoring of
Q10 (30–90 mg PO BID) are two additional supplements.
coagulation profiles is not required with aspirin and disease. L‐carnitine (50 mg/kg PO TID) and coenzyme
clopidrogel and thus they are more commonly used in L‐carnitine is most commonly considered in American
veterinary patients than anticoagulant agents such as cocker spaniels that are taurine deficient. Unlike taurine
warfarin or heparin. deficiency, diagnosis of L‐carnitine deficiency requires
myocardial biopsy, which is rarely performed. In a small
unpublished evaluation of Dalmatians with dilated car-
Dietary Modifications
diomyopathy, one of the authors (SR) found improved
Maintenance of caloric intake is essential in the manage- survival times when taurine, carnitine, and coenzyme
ment of chronic heart failure. Traditionally, restriction of Q10 were administered along with conventional cardiac
sodium was regarded as beneficial for the management therapy.
of heart disease despite concern that very low sodium
diets may further activate the RAAS. Diets that are mildly
(80–100 mg Na/100 kcal) or moderately (50–80 mg Therapy for Refractory Chronic
Na/100 kcal) restricted in sodium should be considered
for patients with chronic CHF. Severely sodium‐restricted Heart Failure
diets (<50 mg Na/100 kcal) are reserved for patients with
advanced heart failure, severe hypertension, or cardio- As previously described, conventional treatment of
genic body cavity effusions. Monitoring of blood electro- chronic CHF in dogs consists of “quadruple” therapy
lytes, in particular sodium and potassium, is important if with furosemide, ACEI, pimobendan, and spironolac-
severely sodium‐restricted diets are fed. tone. In patients with refractory CHF despite conven-
Chronic heart failure is a catabolic state and results in tional therapy, additional treatments are provided in
a progressive loss of body condition and muscle tone. order to combat recurrent symptoms of heart failure.
This “cardiac cachexia” requires adequate caloric and
protein intake. In patients with concurrent renal disease, Additional Diuretics
protein intake needs to be balanced between these com-
peting conditions. The catabolic state is partly a result of Recurrent CHF necessitates gradual increases in the
inflammatory mediators and some evidence suggests the doses of diuretics such as furosemide and spironolac-
benefit of fish‐based omega 3 fatty acids to help slow tone. A common clinical observance is the apparent
weight loss. Supplementation with the omega 3 fatty reduction of diuretic efficacy as furosemide doses
acids is typically considered in patients with weight loss approach 6–12 mg/kg/day in dogs and 3–4 mg/kg/day in
and muscle wasting as well as in patients with ventricular cats. The reasons for diuretic resistance are varied and
arrhythmias (see Chapter 26). Care should be taken to complex. One cause is the reduction of oral bioavailabil-
avoid the fish oils that are combined with other sources ity and resultant decrease in plasma concentration. This,
such as flax seed oil or cod liver oil due to the potential coupled with poor organ perfusion due to low cardiac
for vitamin D toxicosis. Fish oil is dosed based on the output, reduces the delivery of furosemide to the
amount of beneficial omega 3 fatty acids provided. In nephron. In cases of advanced CHF, and particularly in
dogs, eicosapentaenoic acid (EPA) and docosahexaenoic cases of recurrent abdominal or pleural effusion, the
acid (DHA) are dosed at 40 mg/kg and 25 mg/kg per day, authors often consider replacing one or more oral
respectively. administrations of furosemide with a daily subcutane-
Taurine deficiency is a known cause of dilated cardio- ous injection of furosemide. Anecdotal experience indi-
myopathy in cats, but due to universal supplementation cates that restoration of diuresis can often be achieved
in commercial cat food, this form of cardiomyopathy is using this strategy. As with insulin injections, owners
rarely detected. In rare cases of feline taurine deficiency, can quickly learn to how administer SC injections at
patients are supplemented with taurine at 250 mg PO home. Injectable furosemide is light sensitive and own-
BID. Taurine deficiency has also been reported in vari- ers are instructed to keep the drug out of direct light.
ous breeds of dogs, including Newfoundlands, American Injectable furosemide is relatively alkaline and may
cocker spaniels, and golden retrievers. In these dogs, cause reactions at the injection site that include local
taurine‐deficient DCM is treated with 35 mg/kg taurine scabbing or plaque formation. In the authors’ experi-
BID. A complete diet history and whole blood or plasma ence, these appear less common when using the Salix®
taurine assay are recommended by the authors in any brand of furosemide.