By Fabian Barcelo, Founder & Veterinary ScientistVet-reviewed
There is a particular worry that arrives when you run your hands down a dog you have known for years and the shape underneath has changed. The topline feels bonier. The back legs look narrower than they did. The dog is not obviously unwell, but it is not the same animal to touch. That is muscle, and losing it is a different problem from losing weight, with different causes and a different response. At Innovet we get asked about this constantly, usually in the form of what can I feed him to build him back up, so here is the honest version.
Key takeaways
- Muscle loss and weight loss are not the same thing. A dog can hold its weight on the scales while quietly losing muscle and gaining fat.
- Unexplained loss of condition needs a veterinary work-up first. Kidney disease, dental pain, parasites, endocrine disease and cancer all present this way.
- Protein alone does not build muscle. Protein plus the work that asks the muscle to exist does. Feeding more without movement mostly adds fat.
01Three different problems that look alike
Owners tend to use condition, weight and muscle interchangeably, and separating them is the first useful step.
Body weight is the number on the scales. It is easy to measure and, on its own, tells you very little about what the dog is made of.
Body fat is what a body condition score assesses: how much covering sits over the ribs, whether there is a waist from above, and whether there is a tuck from the side.
Muscle mass is assessed separately, mostly over the spine, the shoulder blades, the skull and the hindquarters. An older dog can score perfectly normally for fat while having noticeably lost muscle. This is why a vet runs their hands over a dog rather than just reading a number.
Knowing which of the three has changed determines what you do. A fat dog needs fewer calories. A dog losing muscle needs a diagnosis, adequate protein and something to do with its body.
The number to know
Ideal body condition sits at four to five on the nine-point scale
The nine-point body condition score is the standard tool vets use. At four to five you can feel the ribs easily under a thin layer of covering without pressing, see a waist when you look down from above, and see an abdominal tuck from the side. Below four the dog is underweight. Above five it is carrying more than it should. Learn to do it with your hands once and you can check your own dog every week.
02Why dogs lose muscle
There are several distinct routes, and they call for different responses.
Age. Older dogs lose lean mass gradually, in the same way older people do. It is normal to a degree, accelerated by inactivity, and partly slowed by keeping a dog moving and adequately fed with good quality protein.
Disuse. A sore joint, a period of crate rest, or simply a dog whose walks got shorter. Muscle that is not asked to work disappears quickly, and it is often asymmetric, which is a useful clue. One noticeably smaller hind leg usually means that leg has been spared because it hurts.
Illness. This is the one that matters most. Chronic kidney disease, liver disease, heart disease, endocrine conditions, dental pain, intestinal parasites, malabsorption and cancer can all cause loss of condition, sometimes long before anything more obvious appears.
Simply not enough food. Less common but real, particularly in working dogs, dogs in multi-dog households where feeding is not supervised, and dogs whose portion never changed when their workload went up.
If your dog is losing condition and you cannot point to the reason, that is a veterinary appointment, not a shopping decision. Reaching for a protein supplement to fix an undiagnosed illness delays the thing that would actually have helped. Bring a recent weight history if you have one.
03What actually rebuilds condition
Muscle is built when a body has both the raw material and a reason to keep it. Miss either half and you do not get muscle.
Builds condition
- Adequate high quality protein, spread across the day rather than in one hit.
- Enough total calories. Protein eaten in a calorie deficit gets burned as fuel.
- Consistent daily movement, especially gentle hill work and controlled lead walking.
- Treating the underlying pain, so the dog is willing to use the limb again.
- Patience. Rebuilding lean mass takes months, not a fortnight.
Does not work
- Piling on food without increasing activity. That is fat gain, not muscle.
- Human protein powders, which may contain xylitol, added caffeine or sweeteners that are unsafe for dogs.
- Extreme protein loading. Beyond requirement the surplus is simply metabolised.
- Sudden hard exercise in a deconditioned dog, which risks injury.
- Supplementing around an undiagnosed illness.
Food supplies the material. Movement supplies the reason. A dog only keeps the muscle it is asked to use.Innovet
A note on xylitol, because it is the most dangerous item on that list. It is a sweetener common in human protein powders, peanut butters and sugar-free products, and it is highly toxic to dogs even in small amounts. Never give a dog a product intended for people without checking the label for it. Our guide to whether dogs can have protein powder goes through this properly.
04Where protein pet supplements genuinely help
A healthy adult dog on a complete diet, in normal work, is already getting adequate protein. Adding more will not build a better dog. The situations where a concentrated protein supplement does earn its place are narrower and more specific.
Older dogs. Ageing dogs often need proportionally more protein, not less, to hold lean mass, provided kidney function is normal. This is a common misunderstanding, and worth raising with your vet at the annual check. We cover it in our guide to senior dog and cat nutrition.
Recovery. After surgery, illness or injury a dog has increased protein demand at exactly the point its appetite is lowest. A concentrated source that goes into a small volume of food is genuinely useful here. See post-surgery and recovery nutrition.
Genuinely hard-working dogs. Station and working dogs in Australian conditions, and sporting dogs in serious training. Our piece on protein for active and working dogs covers the demands.
Poor appetite. When a dog is eating less than it should, nutrient density per mouthful matters more than total volume. Our guide to liquid and powdered nutrition for dogs that will not eat deals with this case.
05How to actually do it
Weigh the dog fortnightly and record it, because memory is unreliable and a slow trend is invisible day to day. Score body condition and muscle by hand at the same time. Change one thing at a time so you know what worked. Increase food gradually rather than in one jump, since a sudden increase mostly produces loose stools. Build activity back the same way, adding a little each week. And give it three months before you judge, because lean tissue is slow.
If the dog is not improving on a sensible plan, go back to your vet rather than adding more supplements. Failure to respond is itself diagnostic information.
For the wider category, see our complete guide to protein for dogs and cats, our guide to dog supplements in Australia, and, for the opposite problem, weight management for dogs and cats.
Frequently asked questions
What is the difference between my dog losing weight and losing muscle?
Weight is the total on the scales and can fall through loss of fat, muscle or fluid. Muscle loss is assessed by feel, mainly over the spine, shoulder blades, skull and hindquarters. A dog can hold a steady weight while losing muscle and gaining fat, which is why vets assess body condition and muscle condition separately rather than relying on the scales.
Can I give my dog human protein powder to build muscle?
It is not recommended. Human protein powders frequently contain xylitol, added caffeine or other sweeteners and flavourings that are unsafe for dogs, and xylitol in particular is highly toxic even in small amounts. Use a product formulated for dogs, and check any human food label carefully before it goes anywhere near your dog.
Do older dogs need more or less protein?
Generally more, not less, to help maintain lean muscle mass, provided kidney function is normal. The assumption that all senior dogs should be on reduced protein is outdated and can contribute to muscle loss. Because kidney health does change this answer, it is worth confirming with your vet at your dog's annual check.
How long does it take a dog to regain muscle?
Months rather than weeks. Lean tissue rebuilds slowly, and the process depends on adequate protein, adequate total calories and consistent activity all being present at once. Weigh and body-condition score fortnightly, and allow around three months before judging whether a plan is working.
My dog is losing condition but eating normally. What should I do?
See your vet. Losing condition while eating well is a meaningful clinical sign and can indicate intestinal parasites, malabsorption, endocrine disease, kidney or liver disease, dental pain or other conditions. It is not a situation to manage with a supplement before a diagnosis.
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