Faecal incontinence in dogs: sphincter or reservoir?
11-year-old German Shepherd that drops formed faecal balls while walking or resting, without adopting a defecation posture or appearing to notice. It has lumbosacral pain, a reduced perineal reflex and poor anal tone.
What type of faecal incontinence does it have and what should be investigated?
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A. Sphincter incontinence of neurological origin: investigate the lumbosacral region (cauda equina syndrome) with CT or MRI
Correct. Formed faeces, without awareness or posture, with a reduced perineal reflex and lumbosacral pain indicate a lesion of the sacral plexus or pudendal nerves. Degenerative lumbosacral stenosis is common in German Shepherds.
B. Reservoir incontinence due to colitis: start soluble fibre and diet
In reservoir incontinence the dog senses urgency and adopts a posture, with soft, very frequent faeces; here the faeces are formed and drop without the dog noticing.
C. A behavioural problem due to cognitive dysfunction: start selegiline
A reduced perineal reflex and poor anal tone are objective neurological findings not explained by a cognitive problem.
D. Perianal fistulas: examine the anal area and start ciclosporin
Perianal fistulas cause dyschezia and tenesmus due to pain, not unaware faecal loss with neurological deficits.
lightbulb Key takeaway
Sphincter incontinence: formed faeces dropping without awareness; neurological causes (cauda equina, sacral lesions, neuropathies) or anal damage (perianal surgery, trauma). Reservoir incontinence: urgency from colitis or masses reducing rectal capacity.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.