Studies demonstrate that up to 80% of post-surgical veterinary patients experience inadequately managed pain. Multimodal analgesia, targeting multiple points in the pain pathway simultaneously, provides superior pain control while reducing side effects of individual agents. Use the Pain Scale AI for objective assessment and the Drug Formulary for species-specific dosing.
The World Health Organization's analgesic ladder, originally developed for human cancer pain, has been adapted for veterinary use as a framework for escalating analgesia:
Step 1 (Mild pain): NSAIDs alone. Appropriate for minor soft tissue procedures, dental prophylaxis, and mild osteoarthritis flares.
Step 2 (Moderate pain): NSAIDs + partial mu agonist (buprenorphine) or adjuvant analgesic (gabapentin, tramadol). Appropriate for mass removals, moderate orthopedic conditions, and abdominal procedures.
Step 3 (Severe pain): NSAIDs + full mu agonist (methadone, hydromorphone, fentanyl CRI) + adjuvant analgesics + regional/local anesthesia. Appropriate for major orthopedic surgery, thoracotomy, amputation, and severe trauma.
Non-steroidal anti-inflammatory drugs are the cornerstone of veterinary pain management, providing anti-inflammatory, analgesic, and antipyretic effects through COX inhibition.
| Drug | Species | Dose | Key Considerations |
|---|---|---|---|
| Meloxicam | Dog | 0.1-0.2 mg/kg PO q24h | COX-2 preferential; most studied veterinary NSAID |
| Meloxicam | Cat | 0.05 mg/kg PO q24h (short-term) or 0.01-0.03 mg/kg q24h (chronic) | Long-term low-dose use supported by evidence in OA cats |
| Carprofen | Dog | 2.2 mg/kg PO q12h or 4.4 mg/kg q24h | Idiosyncratic hepatotoxicity rare but reported |
| Robenacoxib | Cat | 1-2 mg/kg PO q24h (up to 6 days) | COX-2 selective; labeled for perioperative use in cats |
| Grapiprant | Dog | 2 mg/kg PO q24h | EP4 receptor antagonist; not a traditional COX inhibitor |
Warning: NEVER combine NSAIDs with each other or with corticosteroids. The washout period between different NSAIDs should be at least 5-7 days. NSAID use requires adequate hydration; avoid in dehydrated, hypovolemic, or hypotensive patients until fluid resuscitation is complete.
Buprenorphine (0.02-0.04 mg/kg): Partial mu agonist with a ceiling effect. Excellent for moderate pain in cats (OTM route provides good bioavailability in cats). Duration 6-8 hours. Cannot be fully reversed by naloxone due to high receptor affinity.
Methadone (0.2-0.5 mg/kg IM/IV): Full mu agonist with NMDA receptor antagonism. Provides excellent visceral analgesia. Duration 4-6 hours. Preferred pre-medication opioid for many protocols due to NMDA activity reducing wind-up pain.
Hydromorphone (0.05-0.2 mg/kg IM/IV): Full mu agonist. Potent and reliable. Duration 2-4 hours. Causes hyperthermia in cats (37-40% of feline patients); monitor rectal temperature.
Fentanyl CRI (2-5 mcg/kg/hr IV): Short-acting full mu agonist ideal for intra-operative and ICU analgesia. Provides titratable, predictable analgesia. Requires continuous monitoring.
Gabapentin (5-10 mg/kg PO q8-12h dogs; 5-10 mg/kg PO q8-12h cats): Calcium channel alpha-2-delta ligand that reduces neuropathic and central sensitization pain. Essential for chronic pain, neuropathic conditions (IVDD, nerve root compression), and as part of multimodal protocols. Also provides anxiolysis. Takes 5-7 days to reach full effect for chronic pain.
Amantadine (3-5 mg/kg PO q24h): NMDA receptor antagonist that addresses central sensitization and wind-up pain. Particularly valuable when pain is refractory to NSAIDs alone. Evidence supports adding amantadine to meloxicam for osteoarthritis unresponsive to NSAIDs.
Tramadol (dogs: 5 mg/kg PO q8-12h; cats: 2-4 mg/kg PO q12h): Controversial in dogs. Canine metabolism produces minimal active M1 metabolite (mu opioid activity), making it primarily a serotonin/norepinephrine reuptake inhibitor in dogs. More effective in cats due to better M1 metabolite production. Not recommended as sole analgesic.
Local anesthesia provides complete nociceptive blockade at the site of surgery and is one of the most underutilized analgesic modalities in veterinary practice.
Lidocaine splash blocks: 1-2 mg/kg applied directly to surgical site (e.g., ovarian pedicle, incision line). Onset 2-5 minutes, duration 60-90 minutes.
Ring blocks and line blocks: Subcutaneous infiltration around the planned incision site. Use lidocaine (2 mg/kg max dogs, 1 mg/kg max cats) or bupivacaine (1-2 mg/kg max dogs, 1 mg/kg max cats) for longer duration (4-6 hours).
Epidural analgesia: Lumbosacral injection of preservative-free morphine (0.1 mg/kg) with or without bupivacaine (1 mg/kg) provides 12-24 hours of caudal body analgesia. Ideal for hindlimb orthopedic procedures, perineal surgery, and cesarean sections.
The Anesthesia & Analgesia Reference provides detailed CRI calculations, regional block techniques, and species-specific dose adjustments for building multimodal protocols.
Osteoarthritis (OA) affects over 60% of cats aged >6 years and approximately 20% of adult dogs. Chronic OA pain management includes: long-term low-dose NSAID therapy (meloxicam, grapiprant), gabapentin for neuropathic and central sensitization components, amantadine when NSAID response is insufficient, weight management (single most impactful non-pharmacologic intervention), physical rehabilitation (hydrotherapy, laser therapy, therapeutic exercise), and nutraceuticals (omega-3 fatty acids at therapeutic doses, adequan polysulfated glycosaminoglycan).
- Multimodal analgesia targeting multiple pain pathways provides superior pain control with fewer individual drug side effects.
- NSAIDs are the foundation; never combine NSAIDs with each other or with corticosteroids.
- Gabapentin is essential for neuropathic pain and central sensitization; takes 5-7 days for full chronic effect.
- Local/regional anesthesia is underutilized and provides the most complete nociceptive blockade.
- Tramadol is a poor sole analgesic in dogs due to minimal M1 metabolite production; more effective in cats.
- Chronic OA management requires multimodal pharmacologic and non-pharmacologic approaches, with weight management as the highest-impact intervention.