Claude vs Mistral: Cat grief anxiety in multi-cat homes. Join the debate.: Feliway Classic Diffuser

My first read here is that this is grief-related anxiety — which is real, common, and worth taking seriously. For a 7-year-old longhair showing subtle signs, I'd start with a pheromone diffuser rather than supplements, because it works passively and doesn't require the cat to eat or accept anything new. My initial recommendation is the Feliway Classic Starter Kit — plug it in near where your cat spends most of their time and give it 2–3 weeks. It's the most evidence-backed option for this kind of situational anxiety and it's gentle enough that there's no risk in trying it. That said, I want to make sure I'm pointing you to the right thing. A few questions that would sharpen this: are the anxiety signs more physical (hiding, over-grooming) or behavioural (vocalising, aggression toward the other cats)? And has anything else changed in the home recently alongside the loss?

The Feliway Classic diffuser is rated to cover up to 70 square metres, and yes, the included vial is designed to last the full 30 days under normal conditions — though in a very draughty room or with the heating running constantly, you might get slightly less. That said, for this cat's situation, the coverage area matters less than placement. One diffuser in the room where they sleep or spend most time will do more than a higher-coverage unit in a hallway. The 70 square metres is a ceiling, not a guarantee across an open-plan space. I'd still stand by the Feliway Classic Starter Kit as the right call here. It's the most straightforward option for grief-related anxiety in a multi-cat home, and the 30-day vial gives you a proper trial window to see whether it's helping before committing to refills.

The starter kit includes one vial — the diffuser head plus a single 30-day vial. I won't quote you a specific price because these shift between retailers and I'd rather you check Amazon or your local pet shop for the current figure on both the kit and refill vials. Here's my confident final recommendation: get the Feliway Classic Starter Kit and budget for two refill vials alongside it. That gives you a full 90-day run, which is the realistic timeframe for grief-related anxiety to settle in a cat. One diffuser, placed in the room where your cat sleeps or spends most time, is the right call — simple, passive, and the most evidence-backed option available without a vet prescription. If you're not seeing improvement after the first 30 days, that's worth a vet conversation — sometimes grief tips into something that needs a bit more support.