When I was at uni, back during the late 70’s and early 80’s, (and I had a Weimaraner) studying Psychology at the University of New England (NSW –Australia), the Agricultural Sciences students (the farmers of the future) had to do a chemical analysis of a leading brand of Pet Food (canned). They found among other things that it contained nicotine.
Now you don’t have to be a rocket scientist to know that nicotine does not have a nutritional value, its main property is that it is addictive. To what purpose would a pet food company add nicotine? I will leave that to you to decide, but their tag line in advertising was that dogs preferred their brand.
As it happens, my childhood family dog was fed this particular brand, my mother believing the advertising that it was better for the dog than the wonderful food that she made (and had lots of leftovers). This little dog was eventually diagnosed with throat cancer and had to be put down.
In that era, it was a complete shock to me, to realise that corporations were not actually interested in the animal, but focused on their bottom line, getting more sales was the priority, not the health and wellbeing of their customers.