Page 132 - Raw Diet References Book 2019

3. TAURINE

3.1 Introduction

Taurine (2-Aminoethanesulfonic acid = NH2CH2- to be adequate to meet the needs, if their food
CH2-SO3H) is a β-aminosulfonic acid rather than an contains adequate amounts of sulphur-containing
α-carboxylic amino acid (Huxtable 1992). It was first amino acids. In cats, the ability to synthesize taurine is
isolated from the bile of the ox “Bos Taurus” and was limited and insufficient to compensate for the natural
named after it (Huxtable 1992). losses via the conjugated bile acid (taurocholic acid)
in the gastrointestinal tract. Hence taurine is an
Dogs and cats exclusively use taurine to conjugate essential nutrient for the cat.
bile acids. In dogs the rate of taurine synthesis appears

3.2 Cat

Taurine deficiency can lead to feline central but is excreted as such in the urine or in the
retinal degeneration, dilated cardiomyopathy and form of taurocholate or related bile acids via the
reproductive failure. Taurine intake is considered to gastrointestinal tract (Huxtable 1992, Odle et al.
be adequate when plasma levels are greater than 50- ’93). However, balance studies have indicated that
60 µmol/L (Pion et al. 1987, Douglas et al. 1991) or the taurine can be degraded by the intestinal microflora
whole blood concentration 200 µmol/L or higher (Fox (Morris et al. 1994). The composition of the cat food,
2000). as well as the type of production process influence
this intestinal degradation (Morris et al. 1994).
In the late 1980s, the feeding of commercial cat foods Hickman et al. showed that heat-processed cat foods
containing levels of taurine that were considered to resulted in lower taurine plasma levels and greater
be adequate [based on studies with purified diets losses compared to the same food but frozen-
(Burger et al. ’82, NRC 1986)] resulted in low plasma preserved (Hickman et al. 1990 & 1992). This was the
taurine levels in cats, and were associated with consequence of increased sensitivity of taurine to
retinal degeneration and dilated cardiomyopathy intestinal bacterial degradation owing to the heat
(Pion et al.1987). processing (Morris et al. 1994). For this reason the
recommendation for taurine in canned cat food is
Taurine is not degraded by mammalian enzymes, higher than that for dry food or purified diets.

3.3 Dog

Healthy dogs synthesize sufficient taurine from bioavailability of sulphur-containing amino acids and
dietary sulphur-containing amino acids such as increased faecal losses of taurine possibly caused by
methionine and cysteine. Nevertheless, low plasma or rice bran (Backus et al. 2003, Delaney et al. 2003, Fascetti
low whole-blood taurine levels may be seen in dogs et al. 2003, Torres et al. 2003).
fed non-supplemented very low protein diets, or foods
that are low in sulphur-containing amino acids or with In dogs, low plasma levels of taurine (<40µmol/L)
poor availability of the sulphur-containing amino acids may also predispose to dilated cardiomyopathy (Pion
(Sanderson et al. 2001, Backus et al. 2003). et al. 1998). However, some breeds seem to be more
sensitive to develop such side effects (Pion et al. 1998),
Feeding certain lamb and rice foods may increase particularly Newfoundland dogs, in which the rate of
the risk of a low-taurine status, because of lower taurine synthesis is decreased (Backus et al. 2006). The

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