This clinical study was designed to demonstrate the test article (Superiorbute™ Powder [phenylbutazone]) is palatable to horses when administered orally as a top dressing on grain rations.
Twenty (20) healthy, male and female American Quarter and Thoroughbred horses approximately 2 to 18 years age at the time of treatment weighing 455 kg (1000 pounds) to 591 kg (1300 pounds) were enrolled in the study. Five female and five male horses were randomly assigned to each of two groups designated as A and B.
The study was carried out in a two-period cross-over design with two days between periods. In the first period, horses in Group A were given the test article twice a day as part of their grain ration at rates of 2 or 1 grams of phenylbutazone per horse two times per day for five days. (The first three days the horses in Group A received 4 grams of Superiorbute™ Powder and days four and five the horses received the maintenance dose of 2 grams per day). Half of the daily dose of powder was administered orally by mixing it in approximately 1.5 pounds of a palatable grain ration at each feeding. Horses from Group B received a similar amount of the grain ration without the addition of test article in the first period. In the second period, Group A received the grain ration without test article and horses in Group B received the grain ration with test article added. (The first three days the horses in Group B received 4 grams of Superiorbute™ Powder and days four and five the horses received the maintenance dose of 2 grams per day). All horses underwent a physical examination conducted by the investigator two days prior to initial dosing and remained healthy throughout the study.
The average score for the amount of grain consumed when mixed with Superiorbute™ Powder was 3.83. The average score for the amount of grain consumed without the drug product was 3.90. The average score (4 being indicated complete consumption) indicate similar grain ration consumption for both the treated and the untreated groups. The average grain ration consumption score for horses was 3.88 when offered the grain ration medicated at 1 gram per horse b.i.d. and 3.76 when offered the grain ration medicated at 2 grams per horse b.i.d..
The horses completely consumed the medicated grain ration 90.5 percent (181 of 200) of the times it was offered. When offered the grain ration without medication it was completely consumed 93.0 percent (186 of 200) of the time. Further, when offered the grain ration medicated at the 1g phenylbutazone per horse b.i.d., it was consumed 92.5 percent (111 of 120) of the time and when offered at 2 grams per horse b.i.d. it was consumed 87.5 (70 of 80) percent of the time. Refusal of all feed occurred in one instance. The remaining times, at least 1/4th of the grain ration was consumed. Most of the instances of incomplete consumption involved one horse that, after an introductory period for acclimation to the grain ration, seemed to be afraid of the feed container (bucket).
The average time to consume the ration with Superiorbute™ Powder added was 14 minutes and 3 seconds. At the1 g phenylbutazone gram per horse b.i.d. the horses consumed the ration in 12 minutes, 56 seconds on average and at the 2 grams per horse b.i.d. dose the grain ration was consumed in 15 minutes and 44 seconds on average. The average time to consume the control ration was 9 minutes, 47 seconds. The medicated grain ration was consumed slower on average than the non-medicated grain ration and the 2 gram dose was consumed slower that the 1 gram dose, the difference between the consumption times is considered clinically insignificant.
The results from this study indicated that the Superiorbute™ Powder is very palatable when fed with grain ration at either the 2 grams or 1 gram per 500 pounds of bodyweight per day dosages as indicated on the product label.
John Knowles, D.V.M.
Brigham Young University
Animal Science Department
Equine Division
76 West 2230 North
Provo, UT 84602