My bunny was scratching her ears and it was all red around her neck and we took her to the vet and the vet gave an Ivermectin shot. its been 4 days since. we have noticed dandruff flakes coming off now but she is constantly scratching and her paw has become thick with dandruff, with some other black stuff and blood. how long does ivermectin take to work? any suggestions? appointments has been made to visit the vet tomorrow morning.