Studies have now shown that taurine (and carnitine) deficiency can occur in dogs exclusively fed certain commercial pet foods.* These deficiencies may not manifest in clinical signs until months or years have passed, making it difficult for owners or veterinarians to ascribe causation.
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Particularly is this so for dogs being fed so-called "complete and balanced" diets. It would, of course, seem there could be no deficiency in such food. 

But such is not the case, the reason being that deficiencies can apparently occur at lower blood levels of taurine than previously thought. This makes diagnosis difficult. Moreover, most pet foods are low in protein (in spite of pictures and claims). And, unnaturally high fiber from ingredients used to replace protein causes the excretion in the stool of bile acids containing taurine. On top of that, high fiber can cause the loss in the bowel of sulfur-bearing amino acids needed to synthesize taurine. So not only is taurine lost, it is not synthesized. 

You may already be aware of the relevant history on taurine. In the 1980's thousands of cats suffered dilated cardiomyopathy and died due to taurine deficient "100% complete" commercial diets. 

After that event, regulatory agencies, the same ones that declared the deficient foods "complete and balanced," became involved and set taurine minimums for commercial cat foods. (The "min" taurine guarantee is now expressed on all commercial cat food labels. But I don't see how this removes culpability. Why would government agencies responsible for the complete and balanced claim not be liable if pets and owners suffer from reliance on the claim?) 

Regardless of label protein values, the common assumption among consumers these days is that all major nutritional needs are met by so-called "100% Complete and Balanced" diets. Packaging that falsely conveys ingredient and food quality reinforces the notion that pet foods are packed with high grade, carnivorous nutrition. Such nutrition in the wild naturally protects carnivores from taurine and other deficiencies or imbalances. 

To not fall victim to self-serving commercial tactics, no one processed food, regardless of nutritional merit, should be fed exclusively. (See The 100% Complete Pet Food Myth.) It is also the case that the definition of "100% Complete" continues to be updated. Now the definition may have to "shift" and be updated once again. (All the while pet foods are consistently labeled as "100% Complete" and recommended for exclusive feeding.) 

Potential taurine deficiency, and myriad other nutritional deficiencies, excesses, and imbalances are easily avoidable. Use common sense, trust in nature, and make appropriate food choices on behalf of your pet. 

You wouldn't eat one food/meal exclusively, nor would you do that for your kids or family members. The same logic applies to our pets. 

Also, commercial pet diets that sometimes offer less than 1/3 of the protein content consumed by wild canines and felines probably won't suffice... (What is genetically appropriate nutrition? Review this recent data.) 

Feed high quality commercial pet foods, and augment with raw foods, quality supplements, and fresh, home prepared additions and meals for optimum health. 

That has been my consistent message for almost 40 years. Unfortunately only bits and pieces of this message are selected by producers to entice consumers. 

For example, common mid-grade pet food products are now portrayed as containing the most nutritious and premium human foods one could buy at a grocery. This only further encourages total reliance on complete and balanced pet foods. 

My point through the years has been to respect genetic design. This is best done with intelligent selection of commercial foods and supplements, variety, rotation, and home prepared foods – not with the easier so-called perfect commercial pet foods imaged like from a menu at a 5-star restaurant. 

Unfortunately, habits remain unless change is easy. The nutrition of family members – two- or four-legged – is no place to be lazy. 

*J Am Vet Med Assoc. 2003 Oct 15;223(8):1130-6. 
J Anim Sci Technol. 2016 Aug 2;58:29. 
Vet Clin North Am Small Anim Pract. 2006 Nov;36(6):1325-43, vii-viii. 
J Am Anim Hosp Assoc. 2005 Sep-Oct;41(5):284-91.