| Control of pain in lame or operative animals involves broad classes of compounds such as NSAID and opioids (see also
pain management,
Pain Management: Introduction). Delivery of analgesia can be via oral, parenteral, epidural, local, or transdermal routes. Nonpharmacologic pain management strategies include acupuncture therapy, massage, and diet. Commonly used NSAID include firocoxib (5 mg/kg, PO, sid), meloxicam (0.1 mg/kg, IV, SC, PO, sid), carprofen (2.2 mg/kg, PO, bid), ketoprofen (1.0 mg/kg, PO, IV, SC, IM, sid),
etodolac (12.5 mg/kg, PO, sid), and aspirin (22 mg/kg, PO, bid in dogs; 10 mg/kg, PO, every 48 hr in cats). The use of NSAID is contraindicated in animals with hepatic or renal insufficiency, gastroenteritis, coagulopathy, or in animals receiving concurrent corticosteroid therapy. Opioid analgesics bind to m, k, and d receptors in the CNS to provide pain relief. Commonly used opioids include morphine (0.1 mg/kg, IV, SC, IM, every 3-4 hr), oxymorphone
(0.05 mg/kg, IV, IM, SC, every 3-4 hr), hydromorphone (0.1 mg/kg, IV, IM, SC, every 2-4 hr), butorphanol (0.1 mg/kg, IV, IM, SC, every 3-4 hr), and buprenorphine (10 mg/kg, IV, IM, SC, tid). Opioid narcotics can be given with sedatives such as acepromazine (0.5 mg/kg, IV, IM, SC, every 4-6 hr) for enhanced efficacy of analgesia and sedation. Oxymorphone, hydromorphone, and butorphanol are more potent than morphine. Buprenorphine has the longest duration of action.
Another opioid, fentanyl, is most frequently administered via transdermal patches applied for 3 days on shaved areas. Oral opioids used for pain relief include butorphanol (1.0 mg/kg, tid), hydromorphone (0.5 mg/kg, tid), and oxycodone (0.3 mg/kg, tid). Local administration of analgesics involves joint injections with morphine (1 mg diluted in 5 mL of saline) or bupivicaine (1 mL/20 kg body wt) before joint surgery as a preemptive block
of intracapsular pain receptors. Epidural morphine (0.1 mg/kg) in the lumbosacral space is also a useful adjunct for postoperative pain relief in the hindlimbs and for reduced anesthetic requirements. Corticosteroids are considered weak analgesic adjuncts because they indirectly reduce pain by their primary action as local anti-inflammatory agents at the site of injury. Drugs used include prednisone or prednisolone (1-2 mg/kg, PO, sid) or dexamethasone (1-2 mg/kg, IV,
sid). Their use is contraindicated during concurrent treatment with NSAID. |
