Usually eating their crap means a mineral problem it isn't always that but given the age of the dog it's possible and the color change would lead me to think that it is a mineral issue.

The p&p is also made of cordura and you can order whatever number of layers you want. The 4R bay vest as well as the catch vest can be ordered with as many layers you think you might need that's the deal with these guys they build custom vest to suit you and your needs. I run them and couldn't be happier, the 4R guys are good to deal with and when I need more vest I will call them again.