The commercial success of the animal health pet sector has been driven in part by tapping into identified market needs of veterinarians and pet owners. The development and the growth of the pet parasiticide market, especially flea treatments, has been at the vanguard in this success.

The introduction of fipronil and imidacloprid-containing ectoparasiticide treatments over the last 30 years made breaking of the flea life cycle possible. Over the same period, we have seen significant increases in both dog and cat populations, and utilisation of parasiticides, often on a year-round basis. This together with a reported decline in insect populations in nature in the United Kingdom (UK) high-lights the importance of the ecosystem pillar in the “One Health,” principle being considered equally to the animal and human pillars in any risk assessment decision-making process relating to these product types (Holdsworth & Fisher 2025).