CONDITION
Age-Related Muscle Loss
Age-related muscle loss describes the gradual decline in muscle mass and strength that can occur as dogs and cats grow older. The process tends to unfold slowly, often noticed first as a change in how easily a pet rises, jumps, or moves through their day. What once felt effortless may begin to require more deliberation or simply happen less often. Owners often arrive at this question after noticing a leaner appearance over the hindquarters or spine, a slower pace on walks, or hesitation at stairs that were never a concern before. These changes can feel subtle at first, sometimes attributed to 'just getting older', and the boundary between expected ageing and a process worth understanding more closely is not always clear. This page explores what muscle loss can look like in an ageing pet, what may be happening beneath the surface, how the process is assessed, and what approaches exist to support muscle health and function over time.
Why this matters now
Muscle loss tends to become noticeable in dogs and cats from around eight years onwards, though the timing can vary considerably by size and breed. Larger dogs often show changes earlier than smaller ones, and certain breeds with leaner builds may make the loss more visually apparent. The process reflects a shift in the balance between muscle protein synthesis and breakdown, influenced by reduced activity, hormonal changes, and sometimes underlying illness that becomes more common with age.
The decline in muscle mass typically unfolds gradually over months to years, rather than appearing suddenly. Some animals maintain stable muscle mass for long periods before a more noticeable decline, while others show a steady, incremental loss. The rate can be influenced by activity level, nutrition, concurrent disease, and individual metabolic factors, meaning the trajectory varies widely between pets.
Signals & patterns
Early signals
Slower rise from lying down
An owner may notice their pet takes a moment longer to stand, or shifts weight before rising, particularly after rest. This often reflects reduced strength in the hind limbs, where muscle loss tends to appear first.
Reduced jump height or frequency
A cat that previously leapt onto counters with ease may begin to use intermediate steps, or a dog may hesitate at the car boot. These changes can signal diminished power in the muscles that drive explosive movement.
Leaner appearance over the hips
The bony prominences of the pelvis or spine may become more visible, or the muscles along the hindquarters may look flatter. This can be subtle at first and may be noticed during grooming or stroking.
Shorter or less enthusiastic walks
A dog that once pulled on the lead may now walk at a steadier pace, or choose to turn back sooner. This can reflect both reduced muscle endurance and a shift in how comfortable sustained activity feels.
Later signals
Difficulty navigating stairs
Stairs that were once routine may become a deliberate effort, with the pet slowing, bunny-hopping, or choosing to avoid them altogether. This often reflects more significant loss of strength in the muscles that stabilise and propel the hind limbs.
Visible muscle wasting along the spine
The muscles running alongside the vertebrae may appear sunken, making the spine itself more prominent. This pattern can extend along the shoulders and thighs, giving an overall leaner silhouette.
Trembling or instability when standing
Muscle weakness may lead to a tremor in the limbs, particularly the hind legs, or a subtle wobble when the pet is stationary. This reflects the effort required to maintain posture with reduced muscle support.
Click to read about the biological mechanisms
How this is usually investigated
Assessment typically begins with a conversation about the changes an owner has noticed—when they started, how they have progressed, and how they affect daily life. A physical examination follows, allowing the clinician to assess muscle bulk, symmetry, and the ease with which the animal moves and rises. From there, investigation often moves towards ruling out conditions that can accelerate muscle loss, such as hormonal imbalance, chronic pain, or metabolic disease. The pace and symmetry of the change are part of this picture: loss that develops gradually and evenly on both sides over months to years fits a pattern of muscle loss associated with ageing alone (sometimes termed sarcopenia), whereas loss that develops more quickly, is more pronounced on one side, or comes with a reduced appetite or falling body weight fits more closely with muscle wasting driven by an underlying illness (cachexia), which points towards a fuller assessment of that possibility rather than ageing alone.
Physical examination
Chemistry panel
Complete blood count
Total T4
Radiography
Options & trade-offs
Management of age-related muscle loss typically involves a combination of approaches tailored to the individual animal's needs, tolerance, and the practical circumstances of the household. No single intervention addresses all the factors that contribute to muscle decline, so strategies are often layered. What works well for one animal may be less practical or less effective for another, and adjustments over time are common.
Dietary protein adjustment
Increasing the protein content or quality of the diet can help support muscle protein synthesis, particularly in older animals whose metabolic efficiency may have declined. This might involve switching to a food formulated for senior animals with higher protein density, or adding lean protein sources to the existing diet. The goal is to provide sufficient amino acids to meet the demands of muscle maintenance without overloading the kidneys or digestive system.
Trade-offs: Higher protein diets may not be suitable for animals with advanced kidney disease or certain liver conditions, and individual tolerance to dietary change varies. Some animals may experience digestive upset during the transition, and the cost of premium protein sources can be a consideration for some households.
Controlled exercise and physiotherapy
Structured, low-impact activity such as short, frequent walks, controlled stair use, or swimming can help maintain muscle mass and strength by providing regular stimulus for muscle fibres to contract and adapt. Physiotherapy sessions may include targeted exercises, passive range-of-motion work, and techniques such as hydrotherapy or therapeutic laser to support muscle function and joint mobility. The intensity and type of exercise are adjusted to the animal's current fitness, any concurrent pain, and their willingness to engage.
Trade-offs: The response to exercise varies widely between individuals, and those with significant joint disease or neurological impairment may find certain activities uncomfortable or impractical. Sustained engagement requires time and consistency from the owner, and access to facilities such as hydrotherapy pools may be limited or involve additional cost.
Pain management
Addressing chronic pain from conditions such as osteoarthritis or spinal disease can restore an animal's willingness to move and bear weight, which in turn helps preserve muscle mass. This may involve non-steroidal anti-inflammatory drugs, other analgesics, or adjunctive therapies such as acupuncture or joint supplements. The aim is to create a comfort level that allows the animal to remain active without exacerbating injury.
Trade-offs: Long-term use of some pain medications requires monitoring for effects on the kidneys, liver, or gastrointestinal tract, and not all animals tolerate all drugs equally. Pain relief does not reverse muscle loss that has already occurred, and the degree of improvement in mobility can be limited if structural joint damage is advanced.
Treatment of underlying conditions
When muscle loss is accelerated by a specific disease—such as hypothyroidism, diabetes, chronic kidney disease, heart failure, or an underlying cancer—addressing that condition, where this is possible, can slow or partially reverse the decline, though muscle wasting driven by cancer or other chronic illness (sometimes described as cachexia) can behave differently from muscle loss due to ageing alone and may prove more resistant to reversal. This might involve hormone replacement, insulin therapy, dietary modification, or other disease-specific interventions. The effect on muscle mass depends on how early the condition is identified and how fully it can be controlled.
Trade-offs: Not all conditions have straightforward treatments, and some require ongoing monitoring and adjustment. The degree to which muscle recovers once a condition is managed varies; in some cases, muscle lost over a long period may not fully rebuild, particularly in very old animals.
Common misconceptions
"Muscle loss is inevitable with age and nothing can be done about it."
While some decline in muscle mass can occur as part of normal ageing, the rate and extent are influenced by factors including nutrition, activity, and the presence of treatable conditions. Targeted interventions can often slow the process, improve strength, and maintain quality of life for an extended period.
"High-protein diets are dangerous for all older pets."
Older animals without significant kidney or liver disease often benefit from higher-quality protein to support muscle maintenance. The concern around protein and kidney health relates primarily to animals with established renal impairment, and even then, the focus tends to be on protein quality and phosphorus content rather than an outright restriction in all cases.
"If muscle loss is happening, exercise will make it worse."
Appropriate, controlled exercise is one of the most effective ways to maintain muscle mass and strength in ageing animals. The key lies in matching the type and intensity of activity to the animal's current capacity and addressing any pain that might limit movement, rather than avoiding activity altogether.
"Rapid or one-sided muscle loss in an older pet is still just part of normal ageing."
Muscle loss associated with ageing alone (sometimes termed sarcopenia) tends to develop slowly and fairly evenly on both sides of the body. Muscle loss that develops over weeks rather than months, is more marked on one limb or side, or occurs alongside a reduced appetite or falling body weight fits more closely with wasting driven by an underlying illness such as cancer, chronic kidney disease, or heart failure (sometimes termed cachexia), which reflects a different process from ageing muscle loss and is worth distinguishing from it.
Related conditions
Arthritis in Cats
Arthritis in cats can contribute to reduced activity and muscle disuse, which may accelerate age-related muscle loss. Conversely, declining muscle strength may place additional strain on arthritic joints, creating a cycle in which mobility and muscle health influence one another.
Cruciate Ligament Disease in Dogs
Cruciate ligament disease in dogs often leads to prolonged limb disuse during recovery or chronic lameness, which can promote muscle atrophy in the affected leg. In older dogs, pre-existing age-related muscle loss may affect the limb's ability to compensate and recover strength after injury.
Canine Cognitive Dysfunction
Canine cognitive dysfunction and age-related muscle loss both tend to emerge in older dogs and can influence one another—reduced mental engagement may lead to less spontaneous movement, whilst declining physical capacity can limit the environmental interaction that supports cognitive health.
Chronic Kidney Disease in Cats
Chronic kidney disease in cats can contribute to muscle wasting through a combination of reduced appetite, altered protein metabolism, and systemic inflammation. Muscle loss in this context may reflect both the metabolic effects of kidney dysfunction and the broader demands of ageing.
Cushings Disease in Dogs
Cushing's disease in dogs can cause muscle weakness and atrophy, particularly over the limbs and trunk, due to the catabolic effects of prolonged cortisol excess on muscle protein. This process can overlap with age-related muscle loss, sometimes making it difficult to distinguish one influence from the other without further investigation.
Muscle loss in older animals often sits alongside other changes—in joint health, metabolic balance, or overall stamina—that can interact in subtle ways. Understanding how these threads connect may help when thinking about what is changing and what might be worth exploring further. Conversations about mobility, nutrition, and comfort at routine appointments can provide useful context as the picture develops over time.
Last reviewed: 13 September 2026 · Dr Alastair Greenway MRCVS