Frontline Original for Large Dogs 20–40kg (Purple) is a monthly spot-on flea and tick treatment using fipronil as the single active ingredient. It provides straightforward parasite control for large-breed dogs, handling adult fleas, paralysis ticks, brown dog ticks, and biting lice.

Unlike Frontline Plus, the Original formula contains fipronil alone without the S-methoprene that targets flea eggs and larvae. It kills adult fleas and ticks on contact and provides monthly protection against re-infestation. Applied to the back of the neck, the water-resistant formula suits dogs with regular outdoor exposure. For paralysis tick control in heavy-risk areas, fortnightly reapplication is recommended.

Frontline Original suits households where the adult-flea kill is the main priority and environmental life-cycle control is handled separately. It has a long track record in Australian vet clinics and remains a straightforward, no-frills option for owners who prefer the original formula.