The Black Panther (T'Challa) is able to transform into a were-panther in the Marvel Mangaverse
In Marvel's Mangaverse designated as Earth-2301, T'Challa is able to transform into a Were-panther. In Marvel Mangaverse Issue #4, when Doctor Doom attacks the UN summit, T'Challa is shown to transform into a were-panther (image below). However, this is supposed to be his normal ability (as opposed to the other Marvel universes where he wears a suit).

Marvel Mangaverse Issue #4
Addressing the second part of your question, this transformation is neither related to the heart-shaped herb nor is it any hereditary trait. On the contrary, the power of the Black Panther is granted by a spirit (or some deity probably) called Qamatha.
T'Challa: Great Qamatha! Fill my soul with your spirit! Make me BLACK PANTHER!
Marvel Mangaverse Issue #4
Considering you'd also like some other instances, King T'Chaka was also able to transform into a Were-Panther. In the animated movie Ultimate Avengers, when Herr Kleiser attacked Wakanda with his Chitauri army, the Black Panther's mantle was still with T'Chaka. He tried to defend his kingdom but was ultimately killed in the process. However, during this time, we do see T'Chaka transform into a were-panther (watch the video below; transformation at the 3:00 mark)