I just finished reading Food Forensics (2016) by Mike Adams, founder and Science Director of the CWC Labs, and although the book primarily has to do with the toxins that were found via laboratory testing, and how to avoid them in human food, there was testing done on some pet treats that are worth mentioning.
- High amounts of lead were found in popular pet treats made in China. A good reason to read the fine print on the back of packages to make sure it says "Made in the USA". (China has worse problems with heavy metals in the soil and foods than we do in the US, and it's pretty bad here. I warned about treats made in China back in 2012. Remember the largest pet food recall in 2007 that killed thousands of pets? Ingredients sourced from China!)
- Fish treats for cats contained large amounts of cadmium. Fish and other seafoods are known to contain toxic heavy metals. I wrote more extensively on this in 9 Reasons Why You Should Avoid Seafood Cat Foods. They also sell dog foods and treats with fish so the dangers apply to their foods and treats too (see herring strips for dogs below).
- A high level of copper was found in a sea vegetable supplement for pets. Too much copper can have detrimental health effects.
- Gourmet munchy rawhide as well as natural rawhide rings had extremely high levels of lead.
- Herring strips for dogs tested high of mercury.
- Munchy stix (for dogs) tested really high in lead.
- Freeze dried ocean whitefish cat treats were found to be high in mercury.
- Although these items were not listed under pet foods or treats per se, they can be found in some of them or sold as pet treats by themselves: an extremely high amount of arsenic was found in dried shrimp, high levels of cadmium and lead in dried whole anchovy, and also a high amount of mercury in dried shaved bonito.
Brand names are not shown for many products in the book for the simple reason that a book takes so long to publish and distribute that many products tested may have shifted in composition over that time.
Another important point to mention here is that even when buying something that is certified USDA Organic -- whether for people or pets -- know that the USDA's organic standards have no limit whatsoever on heavy metals! This is not good. That means when it comes to toxic heavy metals, even if it's labeled USDA organic, it could be loaded with them!
I highly recommend reading this very informative and eye-opening book for your own benefit as well as for your pets. Awareness is the key.