CONDITION
Nerve Sheath Tumour
A nerve sheath tumour is a growth that arises from the cells that wrap around and support peripheral nerves — the nerves outside the brain and spinal cord that carry signals to and from the limbs, face, and body. These tumours can develop anywhere a peripheral nerve runs, and they tend to grow slowly over weeks to months. In dogs, they occur most often in older animals, and certain larger breeds may be more commonly affected. Owners often first notice a lump under the skin, typically on a leg, or they may observe that their dog is favouring a limb, showing discomfort when moving, or experiencing weakness or altered sensation in a specific area. Because the tumour involves a nerve, signs can include lameness that does not improve with rest, muscle wasting in the affected limb, or changes in how the paw is placed or held. In some cases, a tumour affecting a nerve in the chest or abdomen may cause signs that are less easy to localise. This page explores the signals that may suggest a nerve sheath tumour, what is happening at the level of the nerve and surrounding tissue, how these growths are investigated through imaging and sampling, and the range of approaches that exist for managing them. The goal is to help you understand the nature of the condition and the framework within which decisions are made.
Why this matters now
Nerve sheath tumours tend to appear in middle-aged to older dogs, with most cases occurring after seven years of age. Larger breeds may be represented more frequently in clinical reports, though the condition can arise in dogs of any size. There is no clear seasonal or environmental trigger; these growths appear to develop as part of the gradual accumulation of changes in the cells that support and insulate nerve fibres over the course of a dog's life.
These tumours typically grow slowly, over a period of weeks to months, though the rate can vary between individuals. Early on, the signs may be subtle or intermittent—a slight change in gait or a small lump that is easy to overlook. As the tumour enlarges, it can place increasing pressure on the nerve it surrounds, leading to more persistent lameness, progressive muscle wasting, or altered sensation in the area served by that nerve. In some cases, growth remains localised for an extended period; in others, the tumour may eventually involve nearby tissues or, less commonly, spread to distant sites.
Signals & patterns
Early signals
Subtle lameness or altered gait
The dog may begin to favour one limb, placing weight differently or showing a slight reluctance to bear down fully. This can come and go at first, and may not improve with rest in the way a simple strain might.
Small, firm lump under the skin
A discrete swelling may appear along the course of a limb, often feeling fixed to deeper structures rather than moving freely beneath the skin. It may be noticed during grooming or routine handling.
Mild sensitivity on handling
The dog may flinch, pull away, or show discomfort when the affected area is touched or manipulated, even if there is no obvious external injury. This can be the first indication that something beneath the skin is involved.
Slight muscle softening
The muscles in the affected limb may begin to feel less firm or slightly reduced in bulk compared to the opposite side. This reflects early changes in nerve signalling to the muscle, even before obvious weakness is apparent.
Altered paw placement
The dog may begin to place the paw at an unusual angle or drag the toes slightly, a sign that the nerve controlling fine motor control or sensation in the limb is being affected. This can be intermittent at first.
Later signals
Persistent, non-weight-bearing lameness
As the tumour grows, the dog may become increasingly reluctant or unable to use the limb, holding it up or placing minimal weight on it. The lameness is typically progressive and does not respond to rest or simple pain relief.
Marked muscle wasting
The muscles in the affected limb may become visibly smaller and softer, a process called atrophy, which occurs when the nerve can no longer deliver adequate signals to maintain muscle tone and mass.
Loss of sensation or reflexes
The dog may not respond normally to touch or pressure in the affected area, and reflexes that depend on the involved nerve may be diminished or absent. This reflects significant disruption of nerve function.
Enlarging or ulcerating mass
In some cases, the tumour may grow large enough to distort the overlying skin, which can become stretched, inflamed, or break down. This can introduce secondary complications such as infection or discomfort from the mass itself.
Click to read about the biological mechanisms
How this is usually investigated
Investigation typically begins with a detailed history of when signs first appeared, how they have progressed, and which parts of the body are affected. Physical and neurological examination help localise the problem to a particular nerve or limb region. From there, imaging and tissue sampling are used to characterise the mass and distinguish it from other causes of lameness or swelling.
Physical and neurological examination
Radiography (X-rays)
Advanced imaging (CT or MRI)
Fine-needle aspiration or biopsy
Staging investigations
Options & trade-offs
Management is shaped by the tumour's location, size, and relationship to the affected nerve, as well as the individual animal's age, overall health, and the degree of functional impairment. In many cases, a combination of approaches is used, and what is workable for one owner and dog may differ from what suits another. The goal may be to remove or reduce the tumour, preserve or restore function, or manage discomfort and maintain quality of life over time.
Surgical removal
Surgery aims to remove as much of the tumour as possible, ideally with a margin of normal tissue around it. Because the tumour arises from or involves a nerve, complete removal may require sacrificing part or all of the affected nerve, which can result in permanent loss of function in the area that nerve serves. In some cases, the nerve can be preserved or only partially resected, depending on the tumour's extent and invasiveness.
Trade-offs: Amputation of a limb is sometimes considered when the tumour involves a major nerve in a leg and complete removal is not feasible otherwise; many dogs adapt well to three-legged mobility, though owners vary in their comfort with this option. Surgery in other locations, such as the brachial plexus (the nerve network serving the front limb), may be more difficult and carry higher risks of complication or incomplete removal. Recurrence can occur if tumour cells remain, particularly with infiltrative growths.
Radiation therapy
Radiation delivers targeted energy to the tumour site, aiming to damage the DNA of tumour cells and slow or halt their growth. It may be used after surgery to address residual disease, or as a primary treatment when surgery is not feasible due to the tumour's location or the owner's preference. Treatment typically involves multiple sessions over several weeks.
Trade-offs: Radiation requires general anaesthesia for each session and access to specialist facilities, which may involve travel and cost. It can reduce tumour size and delay progression, but it does not always eliminate the tumour entirely, and late side effects such as fibrosis or chronic changes in surrounding tissues can occur months to years later.
Pain and function management
When removal or reduction of the tumour is not pursued, or alongside other treatments, management may focus on supporting comfort and mobility. This can include medications that address nerve pain, anti-inflammatory drugs, physiotherapy to maintain muscle tone and joint range, and environmental adjustments such as non-slip flooring or ramps.
Trade-offs: This approach does not alter the tumour's growth but can meaningfully improve day-to-day quality of life, particularly in the earlier stages or when progression is slow. Over time, as the tumour enlarges or function declines further, the effectiveness of symptomatic measures may diminish.
Monitoring without intervention
In some cases, particularly when the tumour is small, the dog is older or has other health concerns, or the signs are mild and stable, the decision may be made to observe the tumour over time with periodic examinations and imaging. This allows the situation to be reassessed if and when progression occurs.
Trade-offs: Monitoring avoids the risks and costs of treatment but means living with the possibility that the tumour will grow and cause increasing impairment. It can be a reasonable choice when the animal's overall quality of life is good and the trajectory of the disease is uncertain.
Common misconceptions
"A lump that grows slowly is unlikely to be serious."
Nerve sheath tumours often grow slowly, and this does not indicate whether they are benign or malignant. Some tumours that progress gradually over months can still invade surrounding tissues or, less commonly, spread to distant sites. The pace of growth is one piece of information, but tissue sampling and imaging are needed to understand the tumour's nature.
"If the dog is still using the affected leg, the tumour cannot be causing significant nerve damage."
Nerve function can be partially preserved even when a tumour is compressing or invading nerve fibres. Dogs may continue to bear weight on a limb while showing subtle changes such as altered paw placement, reduced muscle bulk, or decreased sensation. Progressive nerve involvement can occur over time, and early signs are often easy to overlook.
"Removing the tumour will always restore normal function to the limb."
Because nerve sheath tumours involve the nerve itself, surgical removal may require sacrificing part or all of the affected nerve, leading to permanent loss of motor or sensory function in the area that nerve serves. Even when the nerve can be preserved, pre-existing damage from compression or infiltration may not fully reverse. The goal of surgery is often to remove the tumour and prevent further progression rather than to restore what has already been lost.
Related conditions
Soft Tissue Sarcomas
Nerve sheath tumours are classified as a type of soft tissue sarcoma, sharing the tendency to arise from connective tissues and a similar pattern of local growth that can make complete removal challenging. The two conditions may be considered together in discussions about surgical margins and the likelihood of local recurrence.
Osteosarcoma in Dogs
Both nerve sheath tumours and osteosarcoma can present as lameness in a single limb that does not improve with rest, and both tend to affect older, larger dogs. The two conditions are often part of the same differential list when investigating progressive limb pain or weakness, particularly when a mass is palpable or imaging reveals changes near bone or soft tissue.
Horner's Syndrome
A nerve sheath tumour affecting nerves in the neck or chest can occasionally disrupt the sympathetic nerve pathway, leading to the cluster of eye changes seen in Horner's syndrome. The two conditions may therefore be linked when a tumour involves or presses on the structures carrying these signals.
Synovial Cell Sarcoma
Synovial cell sarcoma can arise in soft tissues near joints and may present with similar signs to a nerve sheath tumour when located along a limb, including lameness, swelling, and discomfort. Both tumours require imaging and sampling to distinguish them, and they share considerations around local invasion and the potential for incomplete surgical removal.
Fibrosarcoma in Dogs
Fibrosarcoma is another soft tissue tumour that can develop in or near structures served by peripheral nerves, and distinguishing it from a nerve sheath tumour often requires histological examination. Both conditions share similar management considerations, including the importance of wide margins during surgical removal and the tendency for local recurrence if incomplete excision occurs.
Understanding the location and behaviour of a nerve sheath tumour, and how it relates to the structures around it, can help shape conversations about what is feasible and what trade-offs exist. Other conditions affecting nerves or causing limb weakness may present in similar ways, and the broader context of ageing and cellular change in older dogs is explored elsewhere in the Longevity & Healthspan section. The shape of the investigation and the range of approaches described here provide a framework, but the path forward in any individual case depends on findings, preferences, and what feels workable over time.