When I was first out of college, I used to work in the pet food industry. It is a fascinating business because on one hand you are dealing with the challenges of making a quality product while on the other hand the buyer is not the consumer - and they have a strong emotional attachment to their pet and the purchasing decision.
When the pet food industry was first starting up the big producers were all human food companies - particularly millers - who would make pet food with by-products from their milling operations. Purina Mills, Quaker, etc. There was less of a question about ingredient quality because for the most part the company was using its own human grade by-products (corn, wheat and oat flour that was a "by-product" in the production of cornmeal, grits, oatmeal, etc). They also owned their own production facilities, employed their own quality control scientists, and in some cases had their own kennels for palatability and nutritional testing.
Now most of the "speciality brands" come from contract production, and worse yet, the ingredients come from a global commodities market where it is very difficult to 100% ascertain exactly where the commodity is coming from. I was reading an article last night about how, according to Walmart, 100% of all chicken that they source in China for human consumption is at least partly sourced outside of their approved supply chain - from farms and farmers who may or may not abide by their standards. The corruption is so ubiquitous that they are testing blockchain technology (the same encryption technology used to secure Bitcoin) to give every single chicken product sourced in China a unique digital fingerprint so that you can scan it at the end of the supply chain (the retail store) and instantly know every single participant in the entire supply chain all the way back to the farm.
Until they can guarantee the security of food supply chains outside of this country, I put a premium on "Made in America" farm goods - or countries who can guarantee similar food quality control in their supply chains. It is not always the producers who are at fault; they contract for a certain ingredient and they pay for it and are supposed to receive it. However there is currently a quantitative quality gap between commodities sourced from one country versus the same commodity sourced from another country - and the contract manufacturers will often go with the cheaper source without asking the question "why is it cheaper?".
We had a dog that died after eating chicken jerky treats sold at CostCo that were made in China. It was a big enough issue that CostCo recalled the product, we got a warning in the mail (too late in our case) and a follow-up questionnaire from the FDA.