Disclosed is a bolus for oral administration to an animal, the bolus comprising at least one beneficial substance to be delivered to the animal, the bolus comprising two components which are adhered together by a water-soluble adhesive or sealant, such that the two components are separable in vivo, and wherein at least one of the aforesaid components is frangible in vivo, the frangible component being initially stabilised by the adherence thereto of the other of the aforesaid components, such that separation of the two components in vivo facilitates the breakage of the frangible component.
