This Kong Proactive Care Knotted Bone appears to be a slightly expensive regular rawhide bone. This is yet another licensed Kong-brand product that is not actually made by the Kong Company. The actual company behind it is Jakks Pacific, purveyors of kinda cheap dog and kid stuff. The packaging says it contains a patent protected bio-available form of Vitamin C. The actual ingredients are rawhide, Lactoferrine, Lisozyme, and L-Ascorbyl-2-Polyphosphate. That last one is Vitamin C. I had to look up the others.
Lactoferrin is a protein found in various mammalian secretions, milk seems to have the most. The protein has antimicrobial properties, and it has been clinically proven to improve oral health when used topically. This is definitely a good thing to use on a rawhide chew, but they've spelled it 'Lactoferrine' with an 'e' on the end which is throwing me off a bit. I've only found this spelling on ingredients lists, and I currently believe it to be a misspelling of Lactoferrin and not a sneaky way of making us all think it's got that in there.
"Lisozyme" is hopefully another funky misspelling, because Lysozyme is an enzyme present in saliva and various other things including egg whites. Its antibacterial properties were discovered by Alexander Fleming, the same guy that discovered penicillin. Lysozyme has shown antibacterial properties, so it is often included in human mouthwashes and products for dry mouths. This is also something that make sense to put on a rawhide chew.
I'm still not totally sure why they chose to advertise this bone as having Vitamin C, because I can't find compelling evidence that it does anything for healthy dogs on quality diets. Looks like it's just the generic "boosts the immune system!" claim.
One their website, Jakks Pacific claims that Kong rawhides are made in the USA. However, the package for this one says "Made in Mexico from U.S. beef hides." As the USA is the primary supplier of beef hide for the entire planet, even rawhides from China are usually made from USA beef hide. Not impressed. Not at all. Sisci isn't terribly impressed either, she usually gets to work on rawhides chews right away, and all she's done with this one is carry it around a bit.