Muscle Loss in Senior Dogs: How to Spot It and Help Your Dog Stay Strong

By Caroline Buck, Co-founder of Petaluma

Many pet parents first notice it while petting their dog. The spine or hips feel bonier than they used to, even though the scale reads the same. Some muscle loss is a normal part of aging, and it often happens slowly enough to go unnoticed for months.

So how much muscle loss in senior dogs is normal, how can you check for it at home, and what actually helps? This guide covers what vets call sarcopenia and why muscle matters so much for healthy aging. It also explains when back-leg weakness points to something else, and the everyday steps that help older dogs stay strong.

What is sarcopenia in dogs?

Sarcopenia is the gradual loss of muscle that comes with age, even in dogs that are otherwise healthy. Tufts veterinary nutritionist Lisa Freeman described it in a 2012 review of muscle loss in dogs and cats. It differs from cachexia, which is muscle loss caused by an illness such as heart disease, cancer, or kidney disease.

In a lifelong study of Labrador retrievers, lean body mass held steady from about age 6 to 9 and then declined each year after that (Lawler et al., 2008). The loss can hide behind a normal weight. A dog can gain fat and lose muscle at the same time, so the number on the scale may not change at all.

Why muscle matters for healthy aging

Muscle is one of the clearest markers of healthy aging in people, and early dog research points the same way. In the PURE study, researchers measured grip strength in nearly 140,000 adults across 17 countries. Each 5 kg drop in grip strength was linked to a 16% higher risk of death from any cause. Grip strength predicted death more strongly than blood pressure did.

In dogs, most of the evidence comes from dogs with illness. In a 2019 study of 269 dogs with congestive heart failure, 48% had muscle loss on their muscle condition score. Dogs with muscle loss lived a median of 233 days, compared with 321 days for dogs without it.

Muscle also does daily work that pet parents can see. It steadies joints, powers the climb up the stairs, and helps a dog get up from a nap. When muscle fades, older dogs often move less, and moving less leads to further muscle loss.

How to check your dog's muscle condition

You can check your dog's muscle at home by feeling four areas with a flat hand. The World Small Animal Veterinary Association muscle condition score grades muscle as normal, mild loss, moderate loss, or severe loss. Vets assess it by feeling the spine, shoulder blades, skull, and hip bones.

• Spine: Run your hand along your dog's back. Muscle loss usually shows here first, as the bones of the spine start to feel more prominent.
• Shoulder blades: Feel the flat bones at the top of each front leg. They should be covered by a smooth layer of muscle.
• Hips: Feel the two hip bones on either side of the lower back. Sharp, easy-to-find hip bones can signal muscle loss.
• Head: Feel the top of your dog's head. The muscle over the skull can thin as dogs lose muscle.

Muscle condition and body condition are two separate scores. WSAVA notes that overweight dogs can still have significant muscle loss, which is why it recommends checking both at every vet visit. Ask your vet to score your dog's muscle at the next checkup so you have a starting point to compare against.

Dog losing muscle in the back legs: when it is more than aging

Back-leg muscle loss in an older dog often comes from joint pain or a nerve problem, so a vet visit is a good idea. Dogs with sore hips or knees put less weight on those legs, and unused muscle shrinks. Arthritis is also easy to miss. In a 2024 study of 123 young dogs, about 40% already showed arthritis on X-rays, and owners noticed signs in only about 30% of dogs with painful joints.

Some causes involve the spine. Degenerative myelopathy is an inherited, painless condition that usually starts after age 8 and causes slowly worsening weakness and wobbling in the back legs, according to the Merck Veterinary Manual. Intervertebral disc disease can cause back pain, a reluctance to move, and weakness or paralysis in the back legs.

Signs that need a prompt vet visit

• Your dog suddenly cannot stand, walk, or climb stairs.
• Your dog drags or knuckles over a back foot, or wobbles when walking.
• Muscle loss is clearly worse on one side than the other.
• Your dog cries out, trembles, or seems painful when touched along the back.
• Weakness comes with weight loss, appetite changes, or trouble controlling urine or stool.

Muscle loss with weight loss can also be an early sign of an illness such as heart or kidney disease (Freeman, 2012). Your vet can sort out the cause with an exam and bloodwork.

Protein, weight, and diet for senior muscle

Healthy older dogs often need more protein than younger adults to hold onto muscle. In a classic study, older dogs needed about 50% more protein than young adults to maintain their body's protein reserves (Wannemacher and McCoy, 1966). A veterinary review recommends that at least 25% of a healthy senior dog's calories come from protein (Laflamme, 2005). Our guide to protein for senior dogs covers the numbers in detail, including when kidney disease changes the answer.

Human guidelines moved in the same direction. The PROT-AGE Study Group recommends at least 1.0 to 1.2 grams of protein per kilogram of body weight each day for adults over 65. That is more than the standard adult recommendation. The same group also recommends regular exercise for older adults.

Plant protein and muscle

Plant protein can support muscle well. In a 2018 meta-analysis of nine trials in people doing strength training, soy protein produced similar gains in strength and lean mass as whey and other animal proteins. Dogs need specific amino acids, and a complete and balanced plant-based food can supply all of them. Soy is a complete protein on its own, and peas and chickpeas pair well with grains to fill each other's gaps.

At Petaluma, our senior recipe gets 29% of its calories from protein in lab testing, which is above the 25% guideline. It is formulated by veterinary nutritionists and has more protein than our adult recipe in lab testing.

Keep your dog lean

Extra body fat puts more load on aging joints, and sore joints lead to less movement and more muscle loss. In the lifelong Labrador study, half of the dogs fed freely had hip arthritis on X-rays by age 6. Their leaner littermates did not reach that point until about age 12 (Smith et al., 2006).

Measure meals with the same cup each time, and adjust portions as your dog slows down. Our portion calculator gives a starting point for adult and senior dogs, and our guide on how much to feed a senior dog explains calorie needs by weight.

Omega-3s for joint comfort

The long-chain omega-3s EPA and DHA have the best evidence of any supplement for arthritis in dogs. A 2022 meta-analysis concluded that the research supports omega-3s for managing osteoarthritis in dogs and cats. More comfortable joints make it easier for a dog to stay active. Our guide to joint supplements for senior dogs compares the options.

Exercise and mobility support at home

Daily movement is the other half of keeping muscle. The 2023 AAHA Senior Care Guidelines describe rehabilitation, including exercise therapy and hydrotherapy, as an excellent option for improving mobility and balance in older pets. A veterinarian trained in rehabilitation can build a strengthening plan that fits your dog's joints and energy.

Make home easier to move around

The same AAHA guidelines suggest simple changes that help older dogs stay confident on their feet.

• Better footing: Lay rugs or yoga mats over slick floors, especially where your dog eats and turns.
• Ramps and steps: Use a ramp for the car or the couch so your dog does not have to jump.
• Raised bowls: Lift food and water bowls if bending down seems uncomfortable.
• Supportive gear: A padded harness can help you lift your dog's back end, and grips or boots can add traction.
• A good bed: Choose a supportive bed that is easy to step onto and out of.

AAHA also suggests taking videos of your dog moving. Owners often mistake slow, subtle changes for normal aging, and a video makes changes easier to see and share with your vet.

Related reading: Adult vs. Senior Dog Food, Can Diet Help Your Dog Live Longer?, and our Q&A with Dr. Blake Hawley DVM on our Senior formula.

Frequently asked questions

Is it normal for senior dogs to lose muscle?

Some muscle loss is a normal part of aging, and vets call it sarcopenia. In a lifelong study of Labradors, lean body mass started declining after about age 9 (Lawler et al., 2008). Fast or uneven muscle loss is not typical aging, so ask your vet to check it.

Why is my dog losing muscle in his back legs?

Back-leg muscle loss often comes from joint pain, such as hip or knee arthritis, that makes a dog use those legs less. Nerve and spine problems, including degenerative myelopathy and disc disease, can also cause back-leg weakness, according to the Merck Veterinary Manual. A vet exam can find the cause.

How can I help my senior dog build muscle?

Feed a complete and balanced food with enough protein, keep your dog lean, and keep them moving every day. A veterinary review recommends that at least 25% of a healthy senior dog's calories come from protein (Laflamme, 2005). A rehabilitation vet can design strengthening exercises for your dog.

How do I check my dog's muscle condition?

Feel along your dog's spine, shoulder blades, hip bones, and skull with a flat hand. The WSAVA muscle condition score grades muscle as normal, mild loss, moderate loss, or severe loss. Bones that feel more prominent than before can signal muscle loss, even at a normal weight.

Can plant protein help a senior dog keep muscle?

Yes, when it comes from a complete and balanced food. Dogs need specific amino acids, and many ingredients can supply them. In people doing strength training, a 2018 meta-analysis found that soy protein supported similar gains in strength and lean mass as animal proteins.

When should I worry about muscle loss in my dog?

See your vet promptly if your dog suddenly struggles to stand, wobbles or drags a foot, loses muscle on one side, or loses weight along with muscle. Muscle loss with illness, called cachexia, was linked to shorter survival in a study of 269 dogs with heart failure.

References

1. Freeman LM. Cachexia and sarcopenia: emerging syndromes of importance in dogs and cats. J Vet Intern Med. 2012;26(1):3-17. Link.
2. Lawler DF, Larson BT, Ballam JM, et al. Diet restriction and ageing in the dog: major observations over two decades. Br J Nutr. 2008;99(4):793-805. Link.
3. World Small Animal Veterinary Association. Muscle Condition Score chart for dogs and cats. Link.
4. Leong DP, Teo KK, Rangarajan S, et al. Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study. Lancet. 2015;386(9990):266-273. Link.
5. Ineson DL, Freeman LM, Rush JE. Clinical and laboratory findings and survival time associated with cardiac cachexia in dogs with congestive heart failure. J Vet Intern Med. 2019;33(5):1902-1908. Link.
6. Enomoto M, de Castro N, Hash J, et al. Prevalence of radiographic appendicular osteoarthritis and associated clinical signs in young dogs. Sci Rep. 2024;14:2827. Link.
7. Merck Veterinary Manual. Disorders of the spinal column and cord in dogs (pet owner version). Link.
8. Wannemacher RW Jr, McCoy JR. Determination of optimal dietary protein requirements of young and old dogs. J Nutr. 1966;88(1):66-74. Link.
9. Laflamme DP. Nutrition for aging cats and dogs and the importance of body condition. Vet Clin North Am Small Anim Pract. 2005;35(3):713-742. Link.
10. Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. Link.
11. Messina M, Lynch H, Dickinson JM, Reed KE. No difference between the effects of supplementing with soy protein versus animal protein on gains in muscle mass and strength in response to resistance exercise. Int J Sport Nutr Exerc Metab. 2018;28(6):674-685. Link.
12. Smith GK, Paster ER, Powers MY, et al. Lifelong diet restriction and radiographic evidence of osteoarthritis of the hip joint in dogs. J Am Vet Med Assoc. 2006;229(5):690-693. Link.
13. Barbeau-Grégoire M, Otis C, Cournoyer A, et al. A 2022 systematic review and meta-analysis of enriched therapeutic diets and nutraceuticals in canine and feline osteoarthritis. Int J Mol Sci. 2022;23(18):10384. Link.
14. American Animal Hospital Association. 2023 AAHA Senior Care Guidelines for Dogs and Cats: pain management. Link.