Bladder and Bowel Management in Dogs With Spinal Cord Injury

Abstract

Spinal cord injury in companion dogs can lead to urinary and fecal incontinence or retention, depending on the severity, and localization of the lesion along the canine nervous system. The bladder and gastrointestinal dysfunction caused by lesions of the autonomic system can be difficult to recognize, interpret and are easily overlooked. Nevertheless, it is crucial to maintain a high degree of awareness of the impact of micturition and defecation disturbances on the animal's condition, welfare and on the owner. The management of these disabilities is all the more challenging that the autonomic nervous system physiology is a complex topic. In this review, we propose to briefly remind the reader the physiology of micturition and defecation in dogs. We then present the bladder and gastrointestinal clinical signs associated with sacral lesions (i.e., the L7-S3 spinal cord segments and nerves) and supra-sacral lesions (i.e., cranial to the L7 spinal cord segment), largely in the context of intervertebral disc herniation. We summarize what is known about the natural recovery of urinary and fecal continence in dogs after spinal cord injury. In particular we review the incidence of urinary tract infection after injury. We finally explore the past and recent literature describing management of urinary and fecal dysfunction in the acute and chronic phase of spinal cord injury. This comprises medical therapies but importantly a number of surgical options, some known for decades such as sacral nerve stimulation, that might spark some interest in the field of spinal cord injury in companion dogs.

Keywords: autonomic; bladder; canine; dog; dysfunction; sacral implant; spinal cord injury; urinary and fecal incontinence.

Figure 1

Urodynamic equipment to perform cystometry in dogs; (A) it is composed of a pump (black arrow) infusing sterile fluid into the bladder through a dual lumen catheter placed in the bladder (follow red line); the dual lumen catheter measures water pressure in the bladder which is recorded at the level of a pressure transducer (black dashed arrow) connected to a computer software; (B) shows the pump more closely and the two pressure transducers typically used to measure bladder pressure and rectal pressure; (C) on the left a dual lumen catheter with one lumen used to infused sterile saline in the bladder (transparent port) and one lumen used to measure pressure in the bladder (blue port with blue line extension); on the right a rectal catheter used to measure indirectly abdominal pressure (see Figure 3 for related pressure curves); (D,E) show the two ports of the dual lumen catheter, one large at the tip allowing sterile saline infusion and one 5 cm caudal, smaller and measuring fluid pressure.

Figure 2

Schematic demonstrating placement and function of a canine sacral nerve stimulator for bladder emptying in chronically paraplegic dogs; (A) in dogs with T3-L3 spinal cord lesions, the sacral nerves below the lesion remain intact and can be accessed via lumbo-sacral laminectomy; (B) a “book” electrode containing two gutters can receive a pair of sacral nerves (e.g., the S2 pair) when the implant is slotted underneath the dural cone and cauda equina; (C) the implant is connected via a cable (named a Cooper cable) to a sub-cutaneous transducer that can be palpated by the clinician and the owner; (D) the transducer is activated with a remote system brought close to the skin and the transducer; this generates an electrical current that flows to the implant, stimulate the sacral nerves, and leads to efficient bladder emptying.

Figure 3

Cystometry curves recorded during bladder filling at a constant rate of 10 mL/min with a dual lumen catheter placed in the bladder through the urethra; the purple trace shows bladder pressure; the green trace shows rectal pressure measured from a rectal balloon; the red trace is the “true” bladder pressure or “detrusor” pressure obtaining by subtracting the bladder pressure (purple curve) by the rectal pressure (green trace): this allows correction for increase bladder pressure peaks due to increase in abdominal pressure, e.g., when the dog moves or barks. In this example of a dog with chronic severe T3-L3 spinal cord injury (causing paraplegia and incontinence), one can see a peak of pressure corresponding to manual palpation by the clinician (green flag at the top “manual palpation” used as a test control); the first peak of pressure to the left of the recording is an artifact; further to the right, involuntary peaks of pressure are recorded and flagged (see green flags at the top “leak”) and lead to involuntary emission of urine (i.e., incontinence); during filling, the detrusor pressure slowly rises (here to pressure >50 cmH₂O); however, full voluntary emptying should occur in normal animals when the detrusor pressure reaches ~20 mH₂O and this has not happened here.