pain-assessment

# Pain Assessment ## Overview Validated, species-specific pain assessment tools with interpretation guidance. Includes acute and chronic pain scales, multimodal analgesic protocols, and species-specific pain manifestations (especially feline pain hiding). ## When to Use - User performs perioperative/acute pain assessment or pain management planning - User needs pain scale interpretation or analgesic selection/dosing - Keywords: pain, analgesia, Glasgow, UNESP, FMPI, pain scale, acute pain, chronic pain, multimodal, opioid, NSAID, gabapentin, meloxicam, tramadol ## Glasgow Composite Pain Scale (GCPS) - Dogs **Scoring**: Observer-rated scale; 0-26 points (higher = more pain); sections for behavior, posture, consciousness, physiologic values | Domain | 0 Points | 1 Point | 2 Points | 3+ Points | |---|---|---|---|---| | Vocalization | Silent | Crying/groaning | Howling | Constant vocalization | | Body Tension | Relaxed | Slightly tense | Moderate tension | Rigid/severe tension | | Posture | Normal | Slightly abnormal | Moderately abnormal | Severely abnormal (hunched, stretched) | | Consciousness | Normal | Drowsy | Depressed | Unresponsive | | Appetite | Eating normally | Reduced intake | Not eating | Vomiting/retching | | Responsiveness | Normal behavior | Slightly subdued | Withdrawn | Unresponsive/hostile | **Interpretation**: 0-4 = minimal pain; 5-13 = mild-moderate pain; 14-26 = severe pain **Trending**: More important than absolute score; assess pre-treatment and post-analgesic to evaluate efficacy ## Feline Musculoskeletal Pain Index (FMPI) and UNESP-Botucatu **FMPI** (6 items scored 0-3): Lameness, reluctance to move, pain on palpation, posture abnormalities, activity level, dynamic gait changes - Interpretation: 0-3 = minimal, 4-9 = mild-moderate, 10-18 = severe pain - **Critical**: Cats hide pain; absence of vocalization does NOT indicate absence of pain **FMPI Behavioral Indicators of Pain**: - Reduced activity, reluctance to jump - Abnormal gait or position changes - Reduced grooming/self-care - Behavioral changes (aggression, withdrawal) - Palpable muscle rigidity, guarding **UNESP-Botucatu** (Alternative feline scale): Behavioral components (posture, activity, lameness) + physiologic (appetite, autonomic signs); used primarily in research settings ## Colorado State Pain Scale (Multi-Species) **Acute Pain Categories**: 1. **Pain Behaviors**: Vocalization, posture abnormality, aggression, self-mutilation, attention to wound 2. **Physiologic Signs**: Tachycardia, tachypnea, hypertension, mydriasis, salivation/lacrimation 3. **Wound/Disease Assessment**: Swelling, discharge, redness, lameness severity **Chronic Pain**: Similar assessment but includes behavioral/activity changes (depression, reduced movement, sleep disturbance) ## Multimodal Analgesia Ladder ### Tier 1: Non-Pharmacologic - **Physical**: Rest, ice/heat application, physical therapy, passive range of motion - **Environmental**: Quiet recovery space, soft bedding, frequent positioning ### Tier 2: Oral/Injectable Analgesics (Acute) **NSAIDs** (first-line for inflammatory pain): - **Dogs**: Meloxicam 0.1-0.2 mg/kg daily; carprofen 4.4 mg/kg/day (2.2 mg/kg BID or 4.4 mg/kg SID — do not exceed); deracoxib 1-2 mg/kg daily; firocoxib 5 mg/kg daily (canine dose) - **Cats**: Meloxicam — ⚠️ **FDA black-box warning**; US label is a single one-time 0.3 mg/kg SC dose. If chronic use is justified, ~0.05 mg/kg once daily (lowest effective) with mandatory renal monitoring (see `safety/nsaid-safety`). Do not give repeated 0.1 mg/kg daily as routine. - **Dosing caveat**: NSAIDs contraindicated in dehydration, renal disease, hepatic disease, GI ulceration; monitor PCV/TP, creatinine, BUN **Opioids** (acute severe pain): - **Dogs (acute)**: Morphine 0.5-1 mg/kg IM/SC q4-6h; hydromorphone 0.05-0.1 mg/kg IM/SC q4-6h; buprenorphine 0.01-0.02 mg/kg IM/IV q6-12h - **Cats (acute)**: use **lower** opioid doses — morphine 0.1-0.3 mg/kg IM/SC (higher doses risk excitation/hyperthermia); hydromorphone 0.05-0.1 mg/kg; buprenorphine 0.01-0.02 mg/kg (transmucosal effective) - **Dogs (chronic)**: Tramadol 5-10 mg/kg TID-QID; lower efficacy than traditional opioids; less abuse potential - **Cats (chronic)**: Buprenorphine preferred (longer duration, less hyperthermia risk); 0.01-0.02 mg/kg q6-12h (transmucosal absorption) ### Tier 3: Adjuvant Agents - **Gabapentin** (neuropathic/chronic pain): Dogs 10-20 mg/kg TID; Cats ~10 mg/kg (start 5-10, up to ~20; ≈50-100 mg/cat) BID-TID — 100-200 mg is high for a typical 4-5 kg cat, so start low; slower onset (days-weeks) but excellent for chronic neuropathic pain - **Amantadine** (NMDA antagonist): 3-5 mg/kg daily-BID; useful for chronic pain and opioid tolerance - **Alpha-2 agonists** (acute): Dexmedetomidine 5-10 mcg/kg IM/IV (profound sedation; reversal with atipamezole); not recommended for prolonged pain management - **Corticosteroids** (inflammatory pain, limited duration): Prednisolone 0.5-1 mg/kg initial; taper after acute phase to avoid complications ### Tier 4: Regional/Interventional - **Local anesthetic blocks**: Ring blocks (digit), maxillary/mandibular blocks, intra-articular injections - **Epidural anesthesia**: Morphine 0.1 mg/kg + local anesthetic; prolonged postoperative analgesia - **Joint injections**: Steroid (triamcinolone, dexamethasone) ± local anesthetic for chronic OA ## Species-Specific Pain Indicators ### Dogs - Vocalization (whining, whimpering, howling) - Posture changes (hunched, stretched, shifting weight) - Appetite suppression - Activity reduction - Licking/biting at wound or affected area - Reluctance to stand/move ### Cats - **UNDERREPORT pain behaviors**; quiet cats often in significant pain - Reduced grooming (hunched, unkempt appearance) - Reluctance to move/jump - Hidden behavior (seeking quiet, dark spaces) - Subtle aggression, irritability - Loss of appetite (early indicator) - Altered sleep patterns (restlessness) **Critical**: Absence of vocalization in cats does NOT = absence of pain; behavioral and gait assessment essential ### Small Mammals/Exotics - **Rabbits**: Teeth grinding (bruxism), eye bulging (pain squeeze), immobility, reduced eating, hunched posture - **Rodents**: Reduced activity, porphyrin around eyes (stress), piloerection, huddle posture - **Birds**: Ruffled feathers, reluctance to move, wing drooping, lack of preening ## Perioperative Analgesic Protocol Example (Dog, Soft Tissue Surgery) 1. **Pre-emptive**: Meloxicam 0.2 mg/kg PO/IV (1 hour pre-op) 2. **Intra-operative**: Morphine 0.5 mg/kg IM (30 min pre-op); local anesthetic ring block or incision-line infiltration 3. **Immediate recovery**: Meloxicam q24h × 5-7 days; morphine IM/SC q4-6h PRN first 24-48 hours (assess GCPS) 4. **Home care**: Meloxicam daily × 7-10 days; oral gabapentin 15 mg/kg TID if high-anxiety patient or chronic pain risk ## Opioid/NSAID Considerations **Concurrent Use**: NSAIDs + opioids acceptable (multimodal); reduces required opioid dose, lowers GI ulceration risk **Corticosteroid Washout**: Avoid NSAIDs <1 week after systemic corticosteroid discontinuation (ulceration risk) **Renal Monitoring**: Baseline + 7-14 days into NSAID therapy (assess creatinine, BUN, urine specific gravity); especially critical in geriatric patients, dehydrated animals, or those with pre-existing renal disease **Hepatic Monitoring**: Baseline liver enzymes if prolonged NSAID use (>2 weeks) in at-risk patients ## Key Species Differences - **Dogs**: Tolerate NSAIDs well; opioid tolerance develops over weeks; gabapentin effective for chronic neuropathic pain - **Cats**: Meloxicam dosing controversial/contentious (use judiciously); excellent responders to gabapentin; buprenorphine preferred opioid (higher partial agonist ceiling effect); pain behaviors subtle - **Rabbits/Rodents**: High metabolic rate; shorter analgesic intervals; tramadol less effective; opioids prone to GI stasis (combine with motility agents) - **Exotics**: Species-specific pharmacokinetics vary widely; consult specialized resources before prescribing ## Limitations - **Pain scales**: Observer-dependent subjective assessment; provide framework only, not absolute diagnosis - **Feline pain assessment**: Cats significantly undertreat due to cryptic pain behaviors; provider awareness essential - **NSAID safety**: Contraindications common (renal disease, GI ulceration, dehydration); not universal analgesic choice - **Opioid tolerance**: Develops within days-weeks; rotation or adjuvant strategies needed for chronic pain - **Regional anesthesia**: Requires technical skill; duration limited (4-24 hours depending on agent) - **Chronic pain**: Long-term analgesic strategies less evidence-based than acute protocols; referral to pain specialist recommended for refractory cases