2011 Annual Report
1a.Objectives (from AD-416)
To determine the level of ivermectin in the blood serum of pastured horses that are provided with free-access to a solid, cooked protein supplement that is medicated with ivermectin.
1b.Approach (from AD-416)
Ten horses will be placed in an approximate 20-acre pasture and allowed to freely range the entire area. A single tub containing an ivermectin-medicated protein block will be placed inside a central penning area supplied with water. The protein block will be weighed prior to allowing equine access. Once the horses are allowed access to the treatment block, the block will be weighed twice per week to determine (by weight) the quantity of material consumed by the horses. Once per week the horses will be haltered and a blood sample obtained from the jugular vein of each animal in separate vacuum tubes. Blood samples will be processed to obtain the serum from the whole-blood, and the serum will be frozen for later analysis. Serum samples will be analyzed by HPLC to determine the concentration of ivermectin in each serum sample. All data collected from the study will be tabulated to establish the amount of medicated material consumed and correlated to the concentration of ivermectin in the blood system.
Ten yearling horses have been halter-trained and placed into two pastures. Each group has been provided with a solid, cooked feed supplement protein/mineral block. In addition, the mineral blocks placed in one of the pastures are medicated with ivermectin. Blood samples have been taken weekly from the ivermectin-treated group and will be analyzed in order to determine the ivermectin-concentration present in the serum. Once it has been established that the serum concentration of ivermectin can be maintained above the level known to kill ticks, the untreated and treated horses will be infested with ticks to verify the expected result. Fecal samples from the treated horses have shown 100% control of internal parasites due to the ivermectin treatment.
Monitoring of this agreement is by email, phone, and in-person contacts between ARS and the cooperator.