1,151,896. Intratracheal injection of anthelmintics. MERCK & CO. Inc. 2 Nov., 1966 [3 Nov., 1965], No. 49162/66. Heading A5B. A method for treating animals infected with lungworm comprises intratracheally injecting into the infected animal a solution or suspension of 2 - (2' - thiazolyl) - or 2 - (4' - thiazolyl) - benzimidazole, in a pharmaceutically acceptable liquid carrier. The preferred form is an aqueous suspension of the active agent, which preferably also contain a suspending agent such as polyvinyl pyrrolidine, tragacanth or acacia, and may comprise 5 to 35% by weight of the total composition. The anthelmintic should be of a particle size of up to 10 microns. The method involves slow injection of the composition into the trachea at a point midway between the pharynx and the thoracic inlet, and is suitable for use in cattle, sheep, swine and cats.