Flea prevention for older Cavalier King Charles

Your vet flagging flea prevention in an 11-year-old Cavalier is worth taking seriously — at that age, a heavy flea burden can cause more stress on the system than it would in a younger dog, and some of the milder over-the-counter products simply aren't cutting it anymore. To point you to the right option, a couple of quick questions: roughly how much does your Cavalier weigh, and are you currently using anything — collar, spot-on, or tablet?

That explains it — Bob Martin and similar pharmacy-shelf spot-ons use older active ingredients that fleas in the UK have largely developed resistance to. They're not doing much at this point. At 8kg your girl sits in the small-to-medium range, which is well catered for. Do you have a preference between a monthly tablet and a spot-on? And is she on any heart or other medication — Cavaliers of that age often are, so it's worth knowing before I recommend something.

Good that you mentioned the heart meds — that's important context. NexGard Spectra (the 3.5–7.5kg or 7.5–15kg tablet, she'd be in the upper bracket at 8kg) is a prescription oral treatment that covers fleas, ticks, mites, and most worms in one monthly chew. It's one of the most effective options available and the active ingredients — afoxolaner and milbemycin oxime — have no known interactions with Vetmedin or Frusemide. That said, because she's on cardiac medication and is a senior dog, you do need a vet prescription to get it, which your vet can issue at the same visit or by request. I'd go back to the vet, mention NexGard Spectra specifically, and ask them to prescribe it — they'll almost certainly agree since it's a standard first-line recommendation. You can then fill the prescription on Amazon UK or through an online vet pharmacy, which is often cheaper than buying directly from the surgery.

Yes — NexGard Spectra is licensed for long-term monthly use and there's no contraindication with cardiac drugs. The main thing with any senior dog is just keeping an eye on general health and flagging anything unusual to your vet, which it sounds like you're already doing. The prescription requirement actually works in your favour here: your vet will do a check before issuing it, so you have that safety net built in. Once you have the prescription, the 8kg weight means you'd order the 7.5–15kg pack size.

It's a very common situation — those products are still on shelves and look credible, but resistance has made them largely ineffective. You're doing the right thing by following up on what your vet said. NexGard Spectra should make a real difference, and your Cavalier is lucky to have someone paying close attention at her age.