Dietary taurine-deficiency is a cause of dilated cardiomyopathy (DCM) in cats. While the incidence of clinical cases of feline DCM has markedly decreased since the association between DCM and taurinedeficiency was first recognized, not all cats maintained on taurinedeficient diets develop DCM. The objective was to temporally evaluate left ventricular (LV) function using M-mode echocardiography in 23 cats maintained on a taurinedeficient diet; 20 time-matched, taurine-supplemented cats served as controls. The duration of feeding trials ranged from 6-15 months. No diminution of myocardial function was recorded in a small number of taurine-deficient cats whereas cardiac performance in some taurinedeficient cats diminished to levels characteristic of DCM. Of the taurine-deficient cats, 17 (74%) experienced a greater than 25% reduction in fractional shortening and 21 (91%) had a greater than 25% increase in LV end-systolic shortaxis diameter. On average, LV endsystolic short-axis diameter increased by 70% and fractional shortening decreased by 37% in taurine-deficient cats. Mean velocity of circumferential fiber shortening was similarly reduced in taurine-deficient cats. The greatest rate of change in M-mode echocardiographic variables occurred during the first four months on the taurine-deficient diet. Dietary taurine deficiency leads to a spectrum of changes in myocardial function in domestic cats. While DCM is observed in some cats, decreased systolic pump function and increased LV end-systolic shortaxis diameter are more consistent findings.
In summary, a spectrum of changes in myocardial structure and function was observed in taurine-deficient cats ranging from no diminution in LV performance in a small number of cats to diminished systolic pump function coupled with increased LV chamber size. While taurine deficiency of 6 to 15 months duration did result in cardiac changes consistent with dilated cardiomyopathy in some cats, diminution of systolic pump function and increased LV short axis diameter were more consistent observations. Current findings complement those of Pion et al, who demonstrated improved myocardial function with taurine supplementation in clinical cases of taurine-deficient dilated cardiomyopathy. In addition, present data provide direct evidence for a causal relationship between dietary taurine deficiency and myocardial failure in cats.