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The painful dog (Proceedings)

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Nov 01, 2010

The canine patient presented for apparent pain without an obvious cause can be a diagnostic challenge. Thorough examination is an important step in identifying a source of discomfort and determining appropriate diagnostic testing for further evaluation.

Sources to consider include…
     Head/Cervical Pain

     * Cervical vertebral column - e.g. IVD disease, meningitis, A-A instability
          o Brain disease - neoplasia, Chiari-like malformation
          o Middle/inner ear canal - e.g. otitis media/interna
          o Dental disease - e.g. tooth root abscess
          o Esophageal disease - e.g. esophagitis
          o Retropharyngeal disease - e.g. abscess
          o Glandular tissue - e.g. sialoadenitis
          o Temporomandibular joint - e.g. fracture/luxation
          o Muscle - e.g. masticatory myositis
          o Ocular disease - e.g. acute glaucoma (more likely in presence of ocular signs)

     * Thoracic/Abdominal Pain
          o Thoracolumbar vertebral column - e.g. IVD disease, meningitis, discospondylitis
          o Retroperitoneal disease - e.g. ureteral obstruction, pyelonephritis, abscess
          o Abdominal organs - e.g. pancreas, GI tract
          o Aortic thromboembolism (partial)

     * Caudal Body Pain
          o Lumbosacral disease - e.g. IVD protrusion, stenosis
          o Coxofemoral disease
          o Pelvic disorders - e.g. flat bone tumors of the ilium
          o Other orthopedic disease - e.g. iliopsoas, gracillis, semitendinosus muscle injury
          o Prostatic disease - e.g. prostatitis
          o Perineal disease - e.g. perianal fistula, anal gland abscess

     * Poorly Localizable Pain - may be referred from a focal spot or more diffuse or generalized
          o Meningitis ( arteritis/vasculitis)
          o Polyarthritis
          o Discospondylitis
          o Myositis
          o Hypertrophic osteodystrophy
          o Tick borne diseases
          o Behavioral condition?

     * Therapeutic considerations
          o NSAIDs – generally more effective for osteoarthritis vs. pain of neurologic origin
          o Corticosteroids
          o Tramadol – synthetic opioid, generally well tolerated, 1-5mg/kg in dogs, 1-2mg/kg in cats PO up to q6h; should not be used in patients taking serotonin reuptake inhibitors (e.g. fluoxetine) or monoamine oxidase inhibitors (e.g. selegiline)
          o Gabapentin – works to block calcium channels at the level of the CNS, 5-25mg PO TID, dose limiting effect generally sedation
          o Amantidine – oral NMDA receptor antagonist, 3-5mg/kg PO q24h; shown to improve activity level in dogs with osteoarthritis with concurrent NSAID administration
          o Fentanyl dermal patch – short term solution
          o Acupuncture – needles placed in specific locations induce release of neurotransmitters which act to affect sensory input, generally well tolerated
          o Physical rehabilitation

Suggested reading:
Neuropathic Pain, Mathews, KA, Veterinary Clinics of North America: Small Animal Practice, Update on Pain Management, 38(6), 2008