Flea treatment for senior underweight Whippets

An 11-year-old underweight Whippet is exactly the kind of dog where treatment choice really matters — thin skin, low body fat, and a senior system all affect how a dog processes the chemicals in flea products, so your instinct to be careful is right. That said, doing nothing isn't safe either, because flea infestations cause real stress on an already fragile dog. Before I suggest anything, a quick note on the bigger picture: 95% of fleas aren't on your dog at all — they're in your carpets, bedding, and soft furnishings — so whatever we put on him needs to be part of a plan that also tackles the home. Can you tell me roughly how bad the infestation looks, whether you've seen fleas on him directly or just suspects, and has his vet flagged any liver or kidney concerns at his last check-up?

That's really helpful. At 9kg with low body fat, you're right to avoid anything dosed primarily by weight where there's no buffer — and some of the older permethrin-based products can cause issues in sighthounds specifically, because they metabolise certain compounds differently to other breeds. Herbal options, as you've found, just don't have the knockdown power to break the flea lifecycle. Given his age, his lean build, and the fact his organs are currently in reasonable shape, I'd recommend Advocate spot-on by Bayer. It's a prescription-only product, so your vet needs to supply it, but that's actually a feature here — it means you get a proper weight-checked dose and a brief health check before application. Advocate uses imidacloprid and moxidectin, and it has a strong safety record in senior and underweight dogs. It also covers lungworm, which is worth having at his age. For the home, pair it with Indorex Defence household spray — one can treats an average house and kills flea eggs and larvae for up to 12 months. That combination will actually break the cycle rather than just temporarily reduce numbers.

Yes, it's well established. Sighthounds — Whippets, Greyhounds, Salukis — have lower levels of certain liver enzymes and less body fat as a buffer, which means some compounds, particularly certain pyrethrins and pyrethroids, can reach higher effective concentrations in their system than in a Labrador of the same weight. Permethrin products are the main ones to avoid entirely. Advocate doesn't contain permethrin. The imidacloprid in Advocate has been used in dogs safely for over 20 years, and the moxidectin component is well tolerated even in seniors provided there's no severe organ compromise — which your vet confirmed isn't the case. At 9kg, he'd be on the small-medium dog dose, and because it's prescription, the vet will confirm that before dispensing. I'd feel confident recommending it for a dog in his situation.

In the UK, vets can prescribe based on a recent consultation — typically within the last 12 months — so if his check-up was six months ago and he's not showing any new symptoms, most vets will issue a prescription or dispense it directly over the phone or via an online request. It's worth ringing them, mentioning his weight loss since the last visit, and asking specifically for Advocate for fleas. The weight drop is relevant and they may want to note it. Once you have the Advocate sorted, get the Indorex spray on the home the same day if you can — treat all soft furnishings, skirting boards, and his bedding, and wash the bedding at 60 degrees first. That two-pronged approach should clear this up within a few weeks.

Good plan. One last thing — vacuum thoroughly before you spray the Indorex, and again every couple of days for the next two weeks. Vacuuming stimulates flea pupae to hatch, which brings them into contact with the spray residue and kills them faster. It's the step most people skip and it makes a real difference to how quickly the infestation clears. Your boy is lucky to have someone being this careful about what goes on him.