Hello all, and thanks in advance.
After some searching, we have found some horrific outcomes to this black belly symptom.
Other than this, our rescued 5lb Chihuahua mix has been normal as ever. He had kennel cough last year, but other than that has been healthy. We have regularly given him a very small amount of trifexis, but we have been giving him that for 6+ months, and it just recently turned dark, and now almost black.
Thanks again!
Bradley, Becca, Alfie & Dexter.