The clinical signs of urinary bladder denervation are variable and depend on the lesion location. Lesions of the sacral segments of the spinal cord produce a flaccid bladder, which distends with a large residual volume.
Spontaneous urine leakage occurs continuously through the paralyzed atonic urethral sphincter. Additional urine flow occurs when the abdominal pressure is increased. Lesions of the brainstem or spinal cord anterior to S1 produce reflex dyssynergia, a disturbance in coordination of micturition, wherein the facilitatory influence of the bladder stretch receptor (afferents) maintains tonic activity on the efferents of the urethral sphincter. The lack of inhibition of these reflexes from the upper motor neuron pathways produces hypertonicity of the urethral sphincters and results in an impediment to urine flow. There is a high intravesicular pressure and a large postvoiding urine volume. The urine escapes paroxysmally only when the intravesicular pressure exceeds the sphincter pressure. After approximately 1 month of denervation, local spinal reflexes between the sacral afferent and efferent neurons develop in the S1 to S5 segments, and incomplete voiding occurs. In these cases the residual volume remains large, and the normal urination posture is not attained.■ TABLE 8.12
Diseases of the Spinal Cord, Peripheral Nerve, and Motor End Plate of Large Animals border=0>
| Disease | Signs | Species Affected |
| Occipitoatlantoaxial malformation | Ataxia, spasticity, hyperreflexia, crepitation or pain with neck flexion, head tilt, torticollis, ataxia, visible swelling or asymmetry | All species |
| Fractures and dislocations | Tetraparesis, tetraplegia, paraparesis, paraplegia, hyperreflexia, stiff neck, recumbency, ataxia, acute death, crepitation, pain, swelling | All species |
| Cervical spinal abscesses | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, stiff neck, ataxia, sudden death, crepitation, pain, swelling | All species |
| Cervical vertebral stenotic myelopathy | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, stiff neck, ataxia, strip sweating | Horse |
| Spinal tumor (lymphosarcoma, neurofibroma) | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, ataxia | All species |
| Equine herpesvirus myeloencephalopathy | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, ataxia, flaccid anus, flaccid tail, dysuria, distended bladder, impacted rectum, urine scalding | Horse |
| Copper deficiency | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, ataxia | Sheep, goat |
| Cauda equina neuritis | Pruritus in perineum, hair loss in perineum, analgesia in perineum, flaccid tail, flaccid anus, paraphimosis, dysuria, facial palsy, head tilt, leaning, nystagmus | Horse |
| Ischemic myelopathy (fibrocartilaginous embolism) | Paraplegia, tetraplegia, flaccid tail, flaccid anus, areflexia at site of lesion, hyperreflexia distal to site of lesion, ataxia | Horse, sheep |
| Postanesthetic myelopathy | Paraparesis to paraplegia, ataxia, hypalgesia, scoliosis | Horse, cattle |
| Caprine arthritis-encephalitis virus | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, ataxia | Goat |
| Segmental myelitis | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, stiff neck, ataxia, strip sweating, hyporeflexia, areflexia, lower motor neuron deficit, facial nerve paralysis, jaw drop | Horse |
| Developmental defects (spina bifida, Arnold-Chiari syndrome, syringomyelia, hemivertebrae, spinal cysts) | Paraplegia, paraparesis, tetraplegia, tetraparesis, hypotonia, atonia, neurogenic atrophy, torticollis, scoliosis, kyphoscoliosis, misshapen tail, absence of skin over dorsal midline | All species |
| Verminous encephalitis | Tetraparesis, tetraplegia, paraparesis, paraplegia, recumbency, ataxia, head tilt, hyporeflexia, areflexia, hyperreflexia, hypertonia, hypotonia | All species |
| Tetanus | Stiffness, normal reflexes, flashing third eyelid, trismus, bloat, convulsions, coma, raised tailhead | All species |
| Botulism | Flaccidity, ataxia, dysphagia, hyporeflexia, pupillary dilation, facial hypotonia, flaccid tail, flaccid anus | All species |
| Progressive ataxia | Ataxia, recumbency | Charolais cattle |
| Locoism | Ataxia, recumbency, bizarre behavior | All species |
| Dying back axonopathies | Hypermetria, hyperreflexia, ataxia, flaccid tail, flaccid anus, fecal and urine retention, urine scalding, recumbency | All species |
| Elso heel (spastic paresis) | Affected pelvic limb is hyperextended and swings in pendulum fashion; tailhead is elevated | Cattle |
| Bovine spastic syndrome | Episodic hyperextension of the pelvic limb, extension of the limb behind the cattle, head and neck extension | Cattle |
| Peripheral nerve injuries | Areflexia, hypotonia, hyporeflexia, atonia, anesthesia, analgesia of a specific area of limbs or trunk, inability to support weight, normal function of limbs distal to denervated site | All species |
| Ionophore toxicosis (salinomycin, lasalocid, monensin) | Tetraparesis, tetraplegia, ataxia, colic, cardiac dysrhythmia, sudden death | All species |
| Periodic hyperkalemia (HYPP) | Episodic tremors, weakness, spasticity during episodes, recumbency | Horse |
| Myotonia congenital | Episodic weakness, spasticity during episodes | All species |
| Bromide intoxication | Weakness, ataxia, stumbling, closed eyelids, drooped head and neck, paraphimosis | Horse |
| Coyotillo poisoning | Progressive weakness, hypermetria, areflexia | Goat |
| Neosporosis | Recumbency, ataxia, neurogenic atrophy | Calf |
| Cycad palm poisoning | Posterior paresis, elevated tailhead, paraparesis, paraplegia | Cattle |
| Acquired torticollis | Abnormally positioned head and neck | All species |
| Sorghum toxicosis | Ataxia, paraparesis, paraplegia, rabbit-hopping gait, ataxia, recumbency, weight loss | Horse, cattle |
| Stringhalt | Normal at rest, involuntary hyperflexion of the hock and stifle | Horse |
| Tick paralysis | Progressive generalized paresis, ataxia, recumbency, flaccid tail, flaccid anus, weak facial muscles | All species |