My horse has Mange!???????????

My horse has mange. I have had this horse since I was 2, my parents died, so I live on the farm with My lifelong Nanny.... This horse hasn;t had the best life by me.......... I think I caused my horses mange.. My nanny thought since I'm 17 now, I can stay home alone for a weekend while she went to visit her Grandchildren... I threw a two day party, and I drank to much and peed in my horses food and water and we dumped alcohol all over the horse, do you think I caused the mange? We gave her spiked fruit too