Dog that swims every day: which ectoparasiticide to choose
4-year-old Labrador that swims in the river every day during the summer. The owner wants to protect him against fleas and ticks and asks which product suits him best.
Which option is most appropriate for fleas and ticks?
chevron_right Show answer and explanation
A. A fipronil spot-on, reapplied after each swim
Reapplying after each swim means off-label overdosing and releases even more insecticide into the river.
B. An antiparasitic shampoo after every swim in the river
Shampoos kill the parasites present at that moment but have no residual effect: the dog is unprotected until the next wash.
C. Any spot-on, as they are all water-resistant from the first hour
Spot-ons need one or two days to spread over the skin, and very frequent swimming reduces their efficacy and duration.
D. An oral isoxazoline, whose efficacy does not depend on water and which releases no insecticide into the river
Correct. A systemic product is not lost through swimming. In addition, insecticides from topical pet antiparasitics, which are toxic to aquatic invertebrates, have been detected in rivers.
lightbulb Key takeaway
Choose the antiparasitic according to lifestyle: frequent bathing and swimming favour oral products. If the dog lives in a leishmaniosis area, it still needs a sandfly repellent (the isoxazoline does not repel): choose a water-resistant one and follow the product information on bathing.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.