Which mammals cannot synthesize taurine?
It is a misconception that cats cannot synthesize taurine.

Cats can synthesize taurine, just like other mammals, but not enough of it to make up for an entirely taurine-deficient diet. Cats (and other mammalian carnivores) would have consumed a taurine-rich diet in the ancestral environment. It is only when they are fed vegetable/fruit/grain-derived foods that they show symptoms of taurine deficiency--because those foods have low quantities of taurine and other taurine precursors.

Other domesticated or captive carnivorous mammal species are at risk of taurine-deficiency if they are fed vegetable-derived foods, though members of the cat family (Felidae) are particularly susceptible.



Primary reference: This 2003 paper about taurine concentrations in animal feed, especially the 'Discussion' section.


  Taurine  is  an  essential nutrient of cats because the rate of taurine synthesis from its dietary sulphur amino acid precursors, cysteine and methionine, is much less than the extent of loss through faecal bile
  acids  and  urine  (Knopf et al.,  1978).  From  an  evolutionary  standpoint,  taurine  was plentiful  in  the  diet  of  a  true  carnivore,  as  high  concentrations  of  taurine  are  found  in muscle  tissue. However,  as  most  domesticated  felines  normally  do  not  consume  living
  prey, they are at risk to become taurine-deficient if not adequately supplied in the diet.