Switching dog flea treatment to spot-on

Switching from a six-monthly tablet to a monthly spot-on is a common move, and it's worth doing carefully so you don't end up with a gap in cover or double-dose your dog by mistake. Before I point you to the right product, a couple of quick questions: how much does your Labrador cross weigh, and do you know roughly when the last tablet dose was given? That'll help me tell you exactly when it's safe to start the spot-on.

Good — at six weeks post-NexGard Spectra you're safely past the active window, so you can start the spot-on now without any overlap risk. One thing worth knowing: NexGard Spectra also covers lungworm and some other worms, so if you're moving purely to a flea spot-on you'll need a separate wormer to plug that gap. Are you planning to keep up with worming separately, or would you prefer a spot-on that handles both?

Perfect, that makes the choice straightforward. For a 32kg Labrador cross I'd go with Frontline Plus for Large Dogs. It's a well-established permethrin and fipronil combination that kills adult fleas, disrupts eggs and larvae, and covers ticks too — so it's doing more than a basic fipronil-only product. Apply it monthly to the skin between the shoulder blades, keep him dry for 48 hours after application, and you're set. It's widely available on Amazon UK and competitively priced for a dog his size. The 'Plus' part is important — the plain Frontline doesn't have the IGR (insect growth regulator) that breaks the flea life cycle, so always make sure you're picking up the Plus version.

It does matter a little. Frontline Plus is water-resistant once it's fully absorbed, which takes about 48 hours. After that, occasional swimming is fine, but frequent immersion — especially with shampoo — will reduce effectiveness over time. For a dog who swims weekly, the practical advice is to apply the spot-on mid-cycle rather than right before a swim, and avoid bathing him in the 48 hours either side of application. If you find it's not holding up well over a full month, you can safely reapply after four weeks — don't shorten the interval below that.

Yes — especially if he's been indoors a lot. Around 95% of a flea population lives in the environment as eggs, larvae and pupae rather than on the dog, so a spot-on alone won't clear an active infestation. Give the house a good vacuum first, then use an environmental spray like Indorex Defence. It kills adults on contact and has an IGR that stops eggs and larvae developing for up to 12 months. Do the carpets, skirting boards, soft furnishings, and anywhere he sleeps. One treatment usually does the job if you vacuum thoroughly beforehand.