Pain Management in the Emergency Patient

In the emergency room, pain is often the item deferred with "let's stabilise first, we'll deal with it after". Yet untreated pain is not merely a comfort issue: it produces tachycardia, hypertension, increased oxygen consumption, immune suppression and delayed healing. Treating pain is therefore part of stabilisation, not a luxury that follows it.

Measure first: "doesn't look painful" is not data

Animals conceal pain, cats especially. A patient sitting quietly is not comfortable; more often it is withdrawn.

The answer is to use validated pain scales. Scales developed for dogs and cats that can be applied quickly in practice are available (the short form of the Glasgow composite measure and the Colorado scales are widely used). These scales:

• Make assessment independent of the observer
• Establish a shared language within the team
• Make post-treatment reassessment meaningful

A practical rule: record the pain score as a routine parameter, alongside temperature and heart rate. What is not measured is not managed.

Facial expression-based assessment in cats (ear position, orbital tightening, muzzle and whisker tension) is particularly valuable; it catches the silent cat.

Multimodal analgesia: one drug rarely does the job

Pain is not transmitted by a single pathway. Combining drugs that act at different points lowers the dose of each while increasing the total effect, and reduces the risk of side effects along the way.

The components combined in practice:

• Opioids — the cornerstone in acute severe pain
• Local and regional blocks — the component with the most value and the least use
• NSAIDs — in the right patient, at the right time
• Adjuncts — infusions such as ketamine and lidocaine

Opioids: first line in the emergency patient

In acute trauma, fractures, acute abdomen and postoperative pain, opioids are the first choice. Their relative cardiovascular safety is the decisive advantage in a haemodynamically fragile patient.

Points to watch:

• Give to effect by titration; adjust to response rather than memorising a fixed dose
• Monitor respiration and depth of sedation
• Dysphoria and mydriasis may be seen in cats; this does not necessarily mean pain persists
• The effect of full agonists is reversible — a safety margin in the fragile patient

When are NSAIDs not appropriate?

NSAIDs are effective analgesics but are contraindicated in a substantial proportion of emergency patients. Do not start them in:

• Hypovolaemia, dehydration or shock — renal blood flow has become prostaglandin-dependent
• Active or suspected gastrointestinal bleeding
• Known renal or hepatic failure
• Concurrent corticosteroid use — the combination markedly increases GI ulcer risk
• Coagulopathy
• Patients at high risk of perioperative hypotension

Practical approach: in the emergency patient, make the NSAID decision after stabilisation and once perfusion has been restored. Until then, provide analgesia with opioids and local blocks.

Local and regional blocks: most gain, least use

This is the only method that interrupts the pain pathway at its source. Once learned, it is quick and carries almost no systemic burden.

Applications that earn their place in emergency practice:

• Infiltration of wounds and lacerations
• Dental blocks for oral procedures
• Intercostal block for rib fractures
• Intrapleural administration after thoracic drainage
• Regional blocks for limb procedures

Local anaesthetics have a narrower total-dose safety margin in cats; calculate from body weight and write the calculation down.

Adjuncts

In severe pain or where central sensitisation has developed, a low-dose ketamine infusion reduces opioid requirement. A lidocaine infusion plays a comparable role in dogs; in cats it is approached more cautiously because of cardiovascular effects.

These agents require monitoring and are for selected patients, not routine use.

Reassessment: there is no one-off analgesia

The most common mistake is giving the drug and considering the matter closed. Pain is dynamic: the drug wears off, the disease progresses, or a procedure creates new pain.

A workable routine:

1. Record a pain score at the outset
2. Administer analgesia
3. Reassess at the drug's expected peak effect
4. If the score remains above target, change the plan — before increasing the dose, add the missing component (most often a local block)
5. Write the home analgesia plan and what the owner should watch for into the discharge instructions

Common mistakes

• Confusing pain with sedation — a motionless patient is not a pain-free patient
• Underestimating pain in cats
• Starting an NSAID in a patient who has not been stabilised
• Skipping local blocks for lack of time
• Loading a single drug and never reassessing
• Discharging without a home analgesia plan

Summary

Pain management in the emergency patient is three steps: measure, treat with multiple components, measure again. Skipping the first and the last renders even the best drug choice ineffective.

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Verification note: This article offers a general framework for clinical approach. For doses, infusion rates and species-specific contraindications, rely on a current veterinary formulary and the version of the WSAVA pain management guidelines in force.