Spot On Solution for Extra Large Dogs kills fleas and ticks on extra large dogs and continues to kill fleas for up to 5 weeks and ticks for up to 4 weeks. It is important to establish a regular flea control routine for dogs and the household. Dogs who spend a lot of time outside are especially at risk from fleas and ticks. Suitable for dogs over 12 weeks of age and weighing between 40-60kg.