Senior Jack Russell losing muscle mass — what helps

Muscle loss in a 12-year-old Jack Russell is genuinely one of the more worrying things to notice — but it's also one of the more manageable ones if you catch it now. The condition is called sarcopenia, and it's common in dogs this age. Before I point you toward anything specific, I want to ask a few quick things: is he still eating well and maintaining his appetite, or has that dropped off too? And has your vet ruled out anything underlying — thyroid issues, dental pain, or anything else that might be driving the weight or muscle change?

Peggy is a great name, and honestly that picture — still active, good appetite, vet not flagging anything sinister — is actually the best-case version of this situation. What you're describing sounds like age-related muscle wasting rather than something pathological, which means targeted nutritional support can genuinely make a difference. The key nutrient here is protein — specifically high-quality, bioavailable protein — along with omega-3 fatty acids, which help reduce the low-grade inflammation that accelerates muscle loss in older dogs. One more question: what is she currently eating? Dry, wet, raw, or a mix?

That's actually a really common and understandable move — 'senior' food sounds like the logical choice — but here's the thing: most supermarket senior kibbles reduce protein to protect kidney function, which was the old thinking. Newer research suggests that healthy senior dogs actually need more protein, not less, to maintain muscle. So ironically, the senior label may have been working against Peggy. I'd suggest two things: first, look at switching to a higher-protein adult food rather than a senior formula — something with a named meat as the first ingredient. Second, and this is the specific product I'd recommend to work alongside that: YuMOVE Senior Plus. It's a supplement developed specifically for older dogs that combines omega-3s from green-lipped mussel, glucosamine, and other actives that support both joint health and the inflammatory processes linked to muscle loss. Jack Russells tend to stay active well into old age, and keeping the joints comfortable also keeps them moving — which is itself the best thing for maintaining muscle. It's widely available on Amazon UK, comes in a tub of chews most dogs eat like treats, and the dose for a small dog like Peggy is low so one tub lasts a while.

Realistically, give it six to eight weeks before you judge it — that's roughly how long it takes for omega-3 levels to build up meaningfully in the body. You won't see a dramatic transformation, but what owners often notice first is that the dog seems a bit more comfortable getting up, moves a little more freely, and stays engaged on walks for longer. The muscle rebuilding piece is slower and also depends on the diet change — the supplement alone won't rebuild muscle if protein intake is still low. So I'd make both changes at the same time and reassess in two months. And if you haven't already, it's worth mentioning the muscle loss specifically at Peggy's next vet visit — not because anything is necessarily wrong, but because a vet can give her a proper muscle condition score and track it over time, which is really useful.

Perfect. When you're looking at kibbles, scan the ingredient list and aim for something where a named protein — chicken, salmon, lamb — is listed first, and where crude protein on the label is at least 25%. That alone will make a meaningful difference for Peggy. Good luck with her — 12 and still active is a tribute to how well she's been looked after.