Quick answer: for a dog losing muscle, the things with real support are regular exercise and enough good quality protein in a diet that suits them. Omega-3 fish oil has the best evidence for arthritis comfort and is used by vets when illness causes muscle loss. HMB, creatine and leucine supplements, popular for people, have very little evidence in dogs. MedPaw is a joint supplement, not a muscle-building product, so we won't claim it builds muscle. Where stiff joints are the reason your dog has stopped moving, we'd recommend MedPaw Hip & Joint Chews alongside exercise and the right diet.
Transparency note: this page is written by MedPaw, which makes a joint supplement. Sources are linked so you can check them. Checked 9 October 2026.
Why dogs lose muscle in the first place
Vets separate two kinds of muscle loss. Sarcopenia is the loss of muscle that comes with age; cachexia is muscle loss caused by illness such as heart disease, kidney disease or cancer (Freeman, Journal of Veterinary Internal Medicine, 2012). On top of either, a dog that moves less because of sore joints loses more muscle from disuse.
This is why no supplement is the first answer. If illness is behind it, the illness needs treating. If it's age and inactivity, the main lever is getting your dog moving again. A 2023 review in Veterinary Focus describes exercise, particularly resistance work, as more effective than nutrition for building muscle, with the two working together (Kopke, 2023).
When to see a vet
See your vet before adding any muscle or protein supplement, and promptly if you notice:
- Weight loss, or muscle loss that seems fast
- Appetite changes, drinking more, vomiting or diarrhoea
- Muscle loss in only one leg, or over the head and face
- Weakness, wobbling, knuckling or collapse
- Muscle loss in a young dog
- A known kidney or liver condition, or regular medication
Supplements are not treatments. They won't fix an underlying illness, and a high-protein product or creatine can complicate things for a dog with kidney disease.
What actually helps, vet and lifestyle first
- Treat pain. A sore dog won't exercise. Pain relief from your vet often unlocks everything else.
- Exercise little and often. Short daily lead walks, gentle hills, sit-to-stands and pole walking. Hydrotherapy and an underwater treadmill are excellent for weak dogs. See our low-impact exercise guide and hydrotherapy for dogs.
- Physiotherapy. A vet physiotherapist can design a strengthening plan; ask your vet for a referral.
- Feed enough protein. Kopke notes older dogs likely need more protein than younger adults. A complete senior or adult food from a reputable maker, chosen with your vet, does more than any powder. See the best protein sources for dogs with joint problems.
- Keep weight right. Extra fat hides muscle loss and strains joints; too thin and there's nothing in reserve.
HMB, creatine, leucine, protein and omega-3: the evidence
Here's what we found in dogs, not people. Most of the strong evidence for HMB and creatine is in humans, and dogs process food differently, so it can't simply be borrowed.
Muscle supplements for dogs: what the evidence says
| Supplement | What the evidence in dogs says | Our verdict |
|---|---|---|
| Protein (through diet) | Muscle is built from protein; older dogs likely need more than younger adults (Kopke, Veterinary Focus 2023) | The foundation. Get the diet right with your vet, especially if your dog has kidney disease |
| HMB (a leucine breakdown product) | Small studies in racing greyhounds and sled dogs looked at performance (Fuller and Rathmacher, 2026); in older dogs its effect is unclear (Kopke, Veterinary Focus 2023) | Not proven for muscle loss in pet dogs. Ask your vet |
| Creatine | Dog studies are small and short; one in eight healthy Beagles found it raised blood creatine and creatinine but didn't measure muscle (Banton et al., 2022) | Not proven for muscle in dogs. Tell your vet, as it can affect a kidney blood test |
| Leucine | Stimulates muscle building in people and rodents; whether supplements help dogs with age-related muscle loss is unclear (Kopke, Veterinary Focus 2023) | Comes from protein in food; no good case for extra |
| Omega-3 (EPA and DHA, fish oil) | The strongest evidence for arthritis comfort in a 2022 review of 72 trials; also used by vets for illness-related muscle loss, though the best amount isn't established (Kopke, Veterinary Focus 2023) | Worth asking your vet about, at a dose they set |
| Egg yolk extract (Fortetropin) | In a company-funded trial of 100 dogs after cruciate surgery, thigh size held steady versus placebo, at a looser statistical threshold than usual (dvm360 report) | Interesting but needs independent confirmation |
| Joint actives (glucosamine, chondroitin, MSM, green-lipped mussel, Boswellia, hyaluronic acid) | Don't build muscle. They support joints; glucosamine and chondroitin did not relieve pain in the 2022 review | Useful where stiff joints are why a dog has stopped moving |
Two things stand out. First, the dog studies on muscle supplements are small, short and often funded by the companies selling the ingredient. Second, none we could find showed a muscle supplement rebuilding muscle in older pet dogs.
How MedPaw fits
We make MedPaw, so to be clear about what it is and isn't. It's a joint supplement. It contains no HMB, creatine or added leucine, and it isn't a protein supplement or a fish oil. Its green-lipped mussel is a natural source of omega-3, but 70mg per chew is not a substitute for a fish oil your vet recommends. Where it fits is the very common case of a dog who has stopped moving because their joints are stiff: supporting the joints alongside pain relief helps them stay active, and activity is what protects muscle.
MedPaw Hip & Joint Chews: the facts
| MedPaw | |
|---|---|
| Format | Soft chicken and bacon flavour chew, given like a treat |
| Joint actives per chew | All six key joint actives: MSM 185mg, glucosamine 170mg, chondroitin 70mg, green-lipped mussel 70mg, Boswellia serrata 30mg, plus hyaluronic acid |
| Also per chew | Vitamin C 33mg, vitamin E 24 IU, zinc 3mg |
| How much | By your dog's weight, doubled for the first three weeks (see the feeding guide) |
| Guarantee | 60 days from delivery, for any reason; email bark@medpaw.co.uk, nothing to send back |
| Allergens | Contains mollusc (green-lipped mussel) and gluten (brewer's yeast); not suitable for dogs with a shellfish allergy |
| What it isn't | A medicine or painkiller. It's a complementary feed that supports joint health |
Our recommendation: get the basics right first: a vet check, pain control, daily exercise and a diet with enough protein. Then, if stiff joints are part of why your dog is doing less, add MedPaw. It's a soft chew most dogs take like a treat, which makes it a handy reward during sit-to-stands. Give it six to eight weeks, and if you're not happy, email us within 60 days for a refund. If your dog has a condition or takes medication, check with your vet first. Try MedPaw Hip & Joint Chews.
For a full guide to choosing, read the best supplement for a dog losing muscle, and see the best fish oil for dogs' joints.
Frequently asked questions
Is HMB safe for dogs?
Small studies in racing and sled dogs reported no adverse effects on blood tests, but there's very little research in older pet dogs or dogs with health conditions, and its benefit for muscle loss in dogs is unclear. Ask your vet before trying it.
Can I give my dog creatine?
There's no good evidence that creatine helps dogs build muscle, and it can raise creatinine, a marker vets use to check kidney function, which may confuse blood test results. Don't give it without talking to your vet, and tell them if your dog is already having it.
Should I give my older dog extra protein for muscle loss?
Older dogs likely need more protein than younger adults, but the best way to provide it is usually through a complete diet chosen with your vet rather than an add-on. Dogs with kidney disease may need a different approach, so always ask first.
Does fish oil help dogs keep muscle?
Omega-3 from fish oil has the strongest evidence for comfort in dogs with arthritis, and vets use it for dogs losing muscle through illness, though the ideal amount isn't settled. Ask your vet for a product and dose for your dog.
What is the best supplement to build muscle in a dog?
There isn't one with strong evidence. Exercise and a good diet build muscle. If stiff joints are stopping your dog exercising, a joint supplement such as MedPaw Hip & Joint Chews can support the joints so your dog stays active.
Does MedPaw build muscle?
No. MedPaw is a joint supplement and we don't claim it builds muscle. It supports joint health, which can help a stiff dog stay active enough to keep their muscle, alongside your vet's advice, exercise and diet.
