Fipronil was discovered in 1987 and was developed initially for use in pest control in agriculture and public health.In dogs and cats, fipronil is available as a high-volume spray or a low-volume spot-on, with activity against ticks, fleas and ear mites. Hair shed from dogs for up to 2 weeks after topical treatment retains sufficient fipronil tokill dust mites (Dermatophagoides spp) coming in contact.