Horse health hides when poisoned

I was having fun shooting any mob in my way with a Poison Tipped Arrow. I accidentaly shot my horse with the arrow and I suudenly rode it and the Horse's health is black. I also tryed to poison my Horse with a Splash Potion of Poison (1:30). It was the same issue. I don't know if this issue is also in 0.15.1 build 1 because I can't sign in to my Xbox Live Account,but can still play on my worlds. If this issue is a duplicate,I'm sorry,I didn't searched because I have no time. Please fix this and I will really appreciate your work.