Page 720 - Small Animal Clinical Nutrition 5th Edition

Cardiovascular Disease 747

Specific evidence is not available to support the idea that
VetBooks.ir foods low in sodium chloride fed to dogs in the early stages of
heart disease will delay disease progression. However, a prudent
recommendation for these patients is to begin avoiding excess
sodium chloride early in the disease process. Thus, at the first
sign of heart disease without cardiac dilatation (Class Ia), foods
with levels of sodium and chloride in the upper part of the rec-
ommended range (0.15 to 0.25% DM sodium) should be intro-
duced. Cardiac dilatation implies abnormal sodium chloride
handling and intravascular volume expansion and, thus, dilata-
tion is a prelude to venous congestion. When cardiac dilatation
becomes evident on radiographs or echocardiograms (Class Ib),
then foods that are even more sodium chloride restricted (sodi-
um = 0.08 to 0.15% DM) are advised (Roudebush et al, 1994;
Rush et al, 2000). As might be expected, moderate to severe
cardiac dilatation, congestion or both conditions (Class II or
III) also require foods with sodium chloride levels in the lower
end of the range.
Water can be a potential source of sodium and chloride.
Distilled water or water with less than 150 ppm sodium should
be considered for patients with advanced CHF in whom more
strictly limited sodium intake is desirable.

Taurine
Taurine can be important in dogs and cats with myocardial fail- Figure 36-7. Effect of nutritional loading with different sodium and
ure. The mechanism of heart failure in taurine-deficient cats chloride salts on plasma renin activity (PRA) in sodium chloride-
and dogs is not well understood.Taurine may function in inac- deprived rats. Bars marked with * are significantly different (p <0.05)
compared with the low-sodium control. These data suggest that
tivation of free radicals, osmoregulation and calcium modula-
chloride is an important determinant of renin secretion by the kid-
tion (Pion et al, 1998). Taurine also has direct effects on con- neys. (Adapted from Kotchen TA, et al. Journal of Laboratory Clinical
tractile proteins and is a natural antagonist to angiotensin II Medicine 1987; 110: 533-539.)
(Lake, 1993; Gentile et al, 1994). Other unidentified factors
may be involved in the development of myocardial failure in
patients with taurine deficiency. Dilated cardiomyopathy and Taurine is not an essential amino acid for dogs. However,
heart failure may result from an inciting or contributing factor, dilated cardiomyopathy has been associated with plasma tau-
or factors, in combination with taurine deficiency (Fox and rine deficiency and low myocardial taurine concentrations in
Sturman, 1992). For example, studies have demonstrated an captive foxes and a small number of dogs (Moise et al, 1991;
association between taurine and potassium balance in cats Kramer et al, 1995; Kittleson et al, 1997; Pion et al, 1998;
(Dow et al, 1992). Inadequate potassium intake may be suffi- Freeman et al, 2001). In dogs, the association between taurine
cient to induce significant taurine depletion and cardiovascular deficiency and dilated cardiomyopathy is strongest in American
disease in healthy cats (Dow et al, 1992). cocker spaniels and golden retrievers (Kramer et al, 1995;
Because taurine is an essential amino acid in cats, there is a Kittleson et al, 1997, 1991; Pion et al, 1998). An association
minimum recommended allowance for taurine in highly di- between taurine deficiency and dilated cardiomyopathy has also
gestible purified foods for healthy adult cats, which is 0.04% been shown in Newfoundlands, Labrador retrievers, Dal-
DM; the minimum recommended allowances for dry expand- matians, English bulldogs, Portuguese water dogs and Irish
ed and moist foods for adult cats are 0.10 and 0.17% DM, wolfhounds (Sanderson, 2006; Vollmar and Biourge, 2004).
respectively (NRC, 2006). Taurine content of foods for cats Even if plasma and whole blood taurine levels are normal in
with cardiovascular disease should probably contain at least canine dilated cardiomyopathy patients, additional taurine may
0.3% DM.Levels of taurine typically recommended for supple- still be beneficial.Thus, it is reasonable that foods for dogs with
mentation of feline cardiovascular patients (250 to 500 mg tau- cardiovascular disease contain added taurine. Because dogs can
rine/day) (Pion et al, 1989) provide approximately twice that synthesize taurine, the level for foods for canine patients can be
much. There are no reports of acute or chronic toxicity related lower than for cats. The recommendation for taurine in foods
to feeding large quantities of free taurine to cats. In one study, for canine cardiovascular disease patients is at least 0.1% DM.
foods containing up to 1.0% DM taurine were fed for up to This is somewhat lower than would be supplied by the typical
three years and no adverse effects were noted (Sturman and recommendation for taurine supplementation of foods for dogs
Messing, 1992).The safe upper limit of taurine in foods for kit- with dilated cardiomyopathy (500 to 1,000 mg taurine/day)
tens is more than 0.89% DM (NRC, 2006). (Pion et al, 1998). In dogs, as in cats, taurine is safe. No reports