[T]

I would wonder if that particular batch of heart might be a bit off. Not rotten, per se, but dogs have super sensitive noses and it could be less fresh than you think or could have some other change from the cow’s diet, medicines, etc. Maybe he’d like to try some heart from a different source. I don’t think I would try masking the smell with vinegar but instead trust your doggy’s nose wisdom :).

Tabitha (Dr. Thompson)
http://naturalalternativesvet.com