A composition which comprises a biologically active agent and a polymer that exhibits a reverse thermal gelation at a physiological temperature, in a carrier, and in which the active agent is in an undissolved form is disclosed herein. Further disclosed herein are methods utilizing the compositions for treating subjects, including non-human subjects, as well as kits for preparing and using a composition. The composition is preferably a sustained release formulation, and is particularly useful for treating animals, where single-dose treatment is desired.
