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

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 2-4 mg/kg BID; deracoxib 1-2 mg/kg daily; firocoxib 5 mg/kg daily
• Cats: Meloxicam 0.1 mg/kg daily (controversial—use lowest effective dose; monitor renal function); consider carprofen alternative
• Dosing caveat: NSAIDs contraindicated in dehydration, renal disease, hepatic disease, GI ulceration; monitor PCV/TP, creatinine, BUN

Opioids (acute severe pain):

• Dogs/Cats (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
• 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 100-200 mg TID; 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