SYMPTOM
Faecal incontinence
Formed or soft stools are found around the house. Sometimes the animal does not seem to notice, and stools may be found after it has been asleep. At other times it seems aware of the urge but cannot hold on long enough to reach its usual toileting place.
Age-Related Sphincter Laxity
Ageing gradually weakens the anal sphincter in senior dogs and cats, and this can allow small amounts of stool to pass without the animal being aware, sometimes as small faecal balls found in the bed. Nerve-related causes produce the same picture, so age is a conclusion reached only once other causes have been ruled out.
Cognitive Dysfunction Syndrome
In older dogs and cats, disorientation and altered awareness can mean stools are passed in the 'wrong' place even though the sphincter itself is working normally; this is more accurately a change in toileting behaviour than a loss of physical control. It is commonly accompanied by other changes such as altered sleep-wake patterns or apparent confusion in familiar rooms.
Lumbosacral Or Cauda Equina Disease
The nerves controlling the anal sphincter and tail exit the spinal cord low in the back, and compression here, seen more often in middle-aged large-breed dogs, especially German Shepherd Dogs, with signs typically beginning at 3 to 7 years of age, can reduce sphincter tone alongside changes in tail carriage or hindlimb strength.
Intervertebral Disc Disease
Disc material pressing on the spinal cord, whether acutely or as a slower degenerative process, can disrupt the nerve pathways to the sphincter; chondrodystrophic breeds such as Dachshunds are recognised as more prone to disc-related presentations. In dogs, a sudden disc extrusion can bring acute, severe signs such as hindlimb paralysis with loss of the ability to urinate, and this is a time-critical presentation.
Degenerative Myelopathy
This slowly progressive, non-painful spinal cord disease of dogs, most common in German Shepherd Dogs, Pembroke Welsh Corgis, Boxers, Rhodesian Ridgebacks and Chesapeake Bay Retrievers and usually seen in dogs over 8 years old, gradually weakens the hindquarters. Loss of bowel and bladder control comes late, once hindlimb weakness is advanced.
Local Anal Or Rectal Disease
A mass, perianal fistulas (anal furunculosis, seen mainly in German Shepherd Dogs), or scarring or injury around the anus, including after anal surgery, can mechanically prevent the sphincter from closing fully, which is a distinct mechanism from a nerve-related loss of control.
Bowel Disease (Reservoir Incontinence)
When diarrhoea, colitis, inflammatory bowel disease or a tumour stops the rectum from holding a normal volume of stool, the animal is usually aware of the need to pass faeces but cannot hold on, so soft stools are passed frequently and in the wrong place. This differs from sphincter incontinence, where small amounts leak without awareness.
Tail-Pull Injury In Cats
In cats, a tail-pull injury (sacrocaudal luxation) can damage the nerves at the base of the tail, causing tail paralysis with urinary and faecal incontinence. In a published study, 55 of 61 cats (90%) regained voluntary urination; cats with more severe neurological injury were less likely to recover and took longer, and cats that did not regain bowel control had shorter survival. The severity of nerve damage cannot be judged at home.
Why timing matters
Early observation
An occasional small stool passed during sleep, with normal toileting the rest of the time, can reflect age-related weakening of the anal sphincter, but the same pattern is typical of nerve-related sphincter incontinence, so it cannot be put down to age at home.
Later presentation
A pattern that becomes more frequent, occurs while the animal is awake and moving around, or is joined by other signs shifts the picture towards an identifiable driver such as a nerve, spinal, or cognitive process.
Because several of the underlying mechanisms (nerve compression, degenerative spinal disease, cognitive change) are themselves gradual processes, the trajectory over weeks to months tends to be more informative than any single incident when onset is gradual. Incontinence that appears suddenly, with hindlimb weakness, back pain or trouble passing urine, follows a time-critical course instead, as with a disc extrusion, an FCE or a tail-pull injury in cats.
Conditions commonly associated
Degenerative Myelopathy
This progressive spinal cord disease can involve the nerves controlling the anal sphincter as it advances.
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Cauda Equina Syndrome
Compression of the nerve roots low in the spine directly affects the pathways controlling sphincter tone.
Intervertebral Disc Disease (IVDD)
Disc material compressing the spinal cord can disrupt the nerve supply to the anal sphincter.
Lumbosacral Stenosis
Narrowing of the spinal canal at the lower back can compress the same nerve roots responsible for sphincter control.
Canine Cognitive Dysfunction
Disorientation associated with cognitive decline can present as apparently unnoticed defecation even when sphincter function is intact.
Anal Sac Adenocarcinoma
A mass arising from the anal sac tissue can physically disrupt normal sphincter closure.
Urinary Incontinence
Though urinary incontinence primarily affects bladder control, in some cases the same nerve or muscle dysfunction that allows urine leakage may also impair the ability to retain or sense bowel movements, particularly when sphincter tone is reduced.
Fibrocartilaginous Embolism (FCE)
When blood supply to a portion of the spinal cord is interrupted, the nerves controlling the bowel and anal sphincter may lose function, resulting in stool being passed without voluntary control or awareness. The pattern depends on which part of the cord is affected.
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Anal Furunculosis (Perianal Fistulas)
Faecal incontinence is a recognised sign of perianal fistulas in dogs and a possible complication of their surgical treatment.
Colitis
Inflammation of the large bowel can stop the rectum holding stool, so the animal is aware of the urge but cannot hold on (reservoir incontinence).
Feline Cognitive Dysfunction
Disorientation in older cats can lead to faeces being passed outside the litter tray even when sphincter function is intact.
When to explore further
A change in tail carriage, hindlimb weakness, or a wobbly gait alongside the incontinence may point towards a spinal or nerve-related contribution.
Urinary leakage occurring alongside the faecal incontinence broadens the picture towards a shared nerve pathway rather than a purely local issue.
A visible or palpable swelling near the anus is worth characterising separately from a nerve-related cause.
Incontinence appearing alongside disorientation, changed sleep patterns, or getting stuck in corners fits more with a cognitive pattern than a physical sphincter problem.
A pattern that is becoming more frequent or is now occurring during waking hours, rather than only during sleep, suggests the underlying driver is progressing.
Incontinence that starts suddenly, after a fall or other injury, or together with back pain, hindlimb weakness, inability to stand or inability to pass urine, is a different picture from a gradual change. ACVS describes loss of pain sensation in the hindlimbs from a ruptured disc as carrying a very poor outlook that depends on how long it has been lost, and pain sensation and bladder emptying cannot be judged at home.
Keeping a simple log of when accidents happen (asleep, just woken, mid-walk) and how often helps characterise the pattern over time. A short video of the animal walking, including from behind, can capture subtle changes in tail carriage or hindlimb placement. Photographing the area around the anus can document any swelling, and noting any parallel change in urinary control, sleep pattern, or general orientation in the house rounds out the picture.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS