Assemblies in accordance with the invention can lead to an exceptionally easy to use, safe, and convenient system and method of applying a fixed dosage of chemicals to which a user might wish to avoid contact, such as parasiticides. In the present invention, a fluid, such as a pesticide or parasiticide, glue, solvent, lubricant, medicament and the like is loaded into a fluid reservoir and the reservoir sealed. The reservoir can be attached to a cap-applicator structure which is in an inactive configuration. In the inactive configuration, a piercing tip remains poised over the reservoir in an inactive configuration without forming an opening in the reservoir. The cap-applicator can have a sharp intsernal piercing tip capable of piercing the reservoir when the assembly is converted into an active configuration. This will allow the user to dispense the liquid out of the reservoir through the applicator.