It is usually not necessary to add taurine to dog food.
http://skeptvet.com/Blog/2018/12/evidence-update-grain-free-and-other-beg-diets-associated-with-heart-disease-in-dogs/ (excerpt from article below)
In some cases, the diets and disease has also been associated with a deficiency in the amino acid taurine. This is an amino acid that dogs do not normally require in the diet since they can make as much as they need. However, in some breeds there appear to be genetic factors that make individuals more susceptible to taurine deficiency, and associated heart disease. These may include reduced production of taurine, increased loss of taurine, or increased need for taurine. Certain diets that have low levels of the ingredients from which taurine is made or that contain substances, such as legumes and some types of. Fiber that make reduce absorption or synthesis of taurine and its precursors or that encourage taurine loss make act in con cert with these genetic factors to lead to deficiency and disease in some dogs. Many of the details in this hypothetical series of steps remain to be understood.
