The study determined the therapeutic management practices of livestock technicians, veterinarians and farmers against surra using diminazene aceturate. The level of drug resistance of Trypanosoma evansi to this trypanocidal drug among treated carabaos in Region 8 (Northern Samar, Leyte and Biliran) was detected and assessed using the standardized single dose test in mice. The extent of diminazene aceturate resistance of trypanosome was compared among the areas. The study also looked into the applicability of the standardized test using mice as a diagnostic tool to determine trypanocidal drug resistance. A total of 198 albino Swiss mice of either sex and about the same age and weight were used. Blood samples were collected in different endemic areas with trypanosome-suspected carabaos and tested using Suratex®, and those positive for Trypanosoma evansi were inoculated into the mice directly at the field. Blood was collected three times from different carabaos in every identified endemic area. Each treatment was replicated three times with six mice for diminazene aceturate and six mice for control per replication. The mice were treated with diminazene aceturate 24 hrs post-inoculation and examined for parasites daily for first three days of post-treatment, every two days thereafter for the first two weeks, and monitored twice a week thereafter for 60 days if the isolate was sensitive, or until its relapse. Trypanosome isolates resistant to diminazene aceturate were observed in endemic areas either in one or two replication sites of the three provinces (Northern Samar, 83.33%; Leyte, 16.6% and Biliran, 100%). The isolates of the three sites from the different endemic areas identified for trypanosomosis based on 72 hrs post treatment and 60-day observation on the relapses of the infection did not differ. The reaction of resistant and nonresistant isolates from different endemic areas of the provinces also did not differ in the treated mice within the 60-day period of parasitological monitoring and observations.