2024 RECOVER CPR Guidelines: What Every Veterinarian Must Know

Introduction

In June 2024, the Reassessment Campaign on Veterinary Resuscitation (RECOVER) initiative published its first comprehensive update to veterinary CPR guidelines since the original 2012 recommendations. Developed by over 200 veterinary professionals using rigorous GRADE methodology — the same evidence appraisal system used by human CPR guideline bodies — these updated guidelines represent the most significant shift in veterinary emergency resuscitation protocols in over a decade.

For AVE candidates, these guidelines are directly relevant to the clinical examination's emergency medicine components, particularly the Small Animal Practice oral module and the Practical Anaesthesia station. For practising veterinarians, the updates mandate several critical changes to established CPR algorithms that could materially affect patient survival.

The guidelines were published as open-access articles in the Journal of Veterinary Emergency and Critical Care (JVECC), making them freely available to all practitioners worldwide.

Why the 2024 Update Matters

The original 2012 RECOVER guidelines established the first evidence-based, consensus-driven CPR recommendations specifically for veterinary patients. They were a landmark achievement that standardised veterinary resuscitation for the first time.

In the 12 years since, substantial new evidence has accumulated from both veterinary and human medicine. The 2024 update addresses key areas where the evidence has shifted:

• Drug dosing protocols have been refined based on outcome data that was not available in 2012
• Species-specific and size-specific compression techniques are now formally codified rather than left to clinical judgement
• Entirely new clinical domains — neonatal resuscitation, first aid, and large animal CPR — have been added
• The evidence grading system has been aligned with current international best-practice methodology

Practitioners and exam candidates who rely on the 2012 protocols risk applying outdated — and in some cases demonstrably inferior — resuscitation techniques.

Basic Life Support: Key Changes

Initial Assessment

The 2024 guidelines specify that the initial CPR assessment — confirming cardiac arrest and initiating compressions — should take no more than 10-15 seconds. Delays in starting chest compressions remain the single greatest modifiable factor affecting survival. Prolonged pulse-checking or auscultation wastes critical time.

Chest Compression Parameters

Rate: 100-120 compressions per minute (Class I, Level A recommendation — the highest evidence grade)

Depth: One-third to one-half of the chest width in lateral recumbency

Duty cycle: Aim for 50% (equal compression and release time). Full chest wall recoil between compressions is essential for venous return.

Size and Shape-Specific Compression Techniques

A major addition to the 2024 guidelines is the formal codification that compression technique must vary with patient morphology. This replaces the previous generic "compress over the widest part of the thorax" approach:

Patient Type	Recommended Technique	Rationale
Large dogs (>15 kg)	Compress over the widest portion of the thorax in lateral recumbency	Thoracic pump mechanism predominates — compressions generate intrathoracic pressure changes that drive blood flow
Barrel-chested breeds (e.g., Bulldogs, Pugs)	Sternal compressions in dorsal recumbency	Barrel chest shape makes lateral compression less effective; sternal approach maximises thoracic pump effect
Small dogs (<15 kg) and keel-chested breeds	Compress directly over the heart in lateral recumbency	Cardiac pump mechanism predominates — direct cardiac compression is more effective in smaller thoraces
Cats	Compress directly over the heart	Cardiac pump mechanism; one-handed circumferential technique (wrapping the hand around the sternum) is effective and recommended

Ventilation

• Compression-to-ventilation ratio: 30:2 for non-intubated patients
• Bag-mask ventilation is now prioritised over mouth-to-nose ventilation in non-intubated animals (improved consistency and reduced infection risk)
• For intubated patients, continuous compressions with asynchronous ventilation at 10 breaths per minute remain the standard
• Tidal volume: 10 mL/kg, delivered over 1 second

Minimising Compression Interruptions

The guidelines reinforce that chest compression interruptions must be minimised throughout the resuscitation effort. Evidence shows that compressor fatigue leads to measurably reduced compression quality within 2 minutes, even when the rescuer does not recognise the decline in their own performance.

Recommendation: Rotate the person performing compressions every 2 minutes, with changeover completed in under 5 seconds.

Advanced Life Support: Major Drug Protocol Changes

The most impactful changes in the 2024 guidelines involve drug selection and dosing during CPR. Several longstanding protocols have been revised or abandoned based on accumulated evidence.

Epinephrine: High-Dose is Gone

Previous (2012) recommendation: High-dose epinephrine (0.1 mg/kg) was considered an option during prolonged CPR when standard dosing was ineffective.

2024 recommendation: High-dose epinephrine (0.1 mg/kg) is no longer recommended at any point during CPR.

• Standard dose: 0.01 mg/kg IV or IO, administered every other BLS cycle for non-shockable rhythms (asystole, pulseless electrical activity)
• Evidence from both human and veterinary studies indicates that high-dose epinephrine may transiently improve return of spontaneous circulation (ROSC) rates but is associated with worse neurological outcomes and reduced overall survival
• The mechanism: excessive alpha-adrenergic vasoconstriction impairs microcirculatory perfusion after ROSC, leading to greater ischaemic brain injury

This is the single most critical drug change in the 2024 update.

Vasopressin: First-Line for Refractory Shockable Rhythms

2024 recommendation: Vasopressin at 0.8 U/kg IV or IO is now prioritised as the first-line vasopressor for refractory shockable rhythms — ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) that persists after initial defibrillation.

This represents a significant shift from the 2012 guidelines, where vasopressin was considered an alternative to epinephrine rather than a preferred agent for a specific rhythm category. The rationale is based on vasopressin's non-adrenergic vasoconstrictive mechanism (V1 receptor mediated), which avoids the deleterious beta-adrenergic effects of epinephrine on myocardial oxygen demand.

Atropine: Single Dose Only

Previous (2012) recommendation: Atropine 0.04 mg/kg IV, with consideration of repeat dosing.

2024 recommendation: If atropine is used for vagally mediated bradyarrhythmias or asystole, it should be administered as a single dose only. Repeated dosing is no longer recommended. Evidence does not support benefit from multiple atropine doses during CPR.

Species-Specific Antiarrhythmics

For refractory shockable rhythms, the 2024 guidelines introduce a species-specific approach to antiarrhythmic selection — a departure from the previous "one protocol fits all" recommendation:

Species	Drug	Dose	Route
Dogs	Lidocaine	2 mg/kg	IV/IO
Cats	Amiodarone	5 mg/kg	IV/IO

The species differentiation reflects known differences in myocardial ion channel pharmacology between dogs and cats. Lidocaine is a sodium channel blocker that is well-tolerated in dogs but has a narrower therapeutic index in cats, where amiodarone (a multi-channel blocker) may be more effective and safer.

Esmolol: A Novel Addition

For refractory shockable rhythms that persist despite defibrillation and first-line antiarrhythmics, the guidelines suggest co-administration of esmolol:

• Loading dose: 0.5 mg/kg IV/IO over 3-5 minutes
• Maintenance: constant rate infusion at 50 mcg/kg/min

This ultra-short-acting beta-1 selective blocker is a new addition to the veterinary CPR pharmacopoeia. Its inclusion reflects human evidence suggesting benefit in "refractory VF" — defined as VF that does not respond to three or more defibrillation attempts plus antiarrhythmic therapy.

Defibrillation Updates

Initial and Subsequent Energy Levels

Attempt	Energy (Biphasic Defibrillator)
First defibrillation	2 J/kg
Subsequent attempts	4 J/kg (doubled from initial)

Monophasic defibrillators, if still in use, require approximately double the biphasic energy. However, biphasic defibrillators are now the standard of care.

Timing Protocol Change

2024 recommendation: For shockable rhythms, defibrillation should precede vasopressor administration. The previous guidelines did not clearly establish this priority sequence.

The rationale: early defibrillation remains the single most effective intervention for ventricular fibrillation. Every minute of delay in defibrillation reduces the probability of successful cardioversion by approximately 7-10%. Any delay — including time taken to draw up and administer drugs — reduces the chance of a successful outcome.

Rhythm Assessment Protocol

After each defibrillation attempt:

1. Immediately resume chest compressions for a full 2-minute BLS cycle
2. Reassess the rhythm at the end of the cycle
3. If the rhythm remains shockable, increase energy to 4 J/kg and defibrillate again
4. Administer vasopressors and antiarrhythmics between defibrillation attempts, not before them

New Clinical Domains

The 2024 guidelines expand the scope of veterinary resuscitation science with three entirely new domains that were not addressed in the 2012 version:

Neonatal Resuscitation

Specific recommendations for resuscitation of newborn puppies and kittens address the unique physiological challenges of neonatal patients. Key differences from adult CPR include:

• Smaller compression depths with finger-tip or two-finger technique
• Higher ventilation rates (approximately 30 breaths per minute)
• Temperature management as a primary intervention — neonates lose heat rapidly and hypothermia dramatically worsens outcomes
• Umbilical vein as a potential vascular access route
• Tactile stimulation (vigorous rubbing with a warm towel) as a first-line intervention before compressions

First Aid

Guidelines for bystander and first-responder care prior to the arrival of veterinary professionals. This domain acknowledges the growing recognition that pre-hospital care significantly influences outcomes, particularly for witnessed cardiac arrests where intervention can begin within seconds rather than minutes.

Large Animal CPR

Recommendations for resuscitation of horses and cattle, where body size and anatomy present unique challenges. External chest compressions are generally not feasible in standing or laterally recumbent adult horses due to thoracic wall rigidity. The guidelines address:

• Foal and calf resuscitation (where external compressions remain viable)
• Internal cardiac massage considerations
• Anaesthetic-related cardiac arrest in horses (the most common clinical scenario)

Veterinary Sepsis Definitions: A Related 2024 Update

Alongside the RECOVER update, 2024 also brought renewed discussion about sepsis definition in veterinary medicine. A significant publication by Cortellini in JVECC highlights the ongoing evolution of how veterinary medicine defines and diagnoses sepsis.

Current Veterinary Approach

Veterinary medicine still predominantly relies on Systemic Inflammatory Response Syndrome (SIRS) criteria to identify sepsis:

• Dogs: 2 or more of 5 SIRS criteria (heart rate, respiratory rate, temperature, WBC count, band neutrophils)
• Cats: 3 or more of 5 SIRS criteria (higher threshold due to stress-related tachycardia and fever in cats)

The Shift Toward Organ Dysfunction

Human medicine transitioned to the Sepsis-3 definition in 2016, which defines sepsis as "life-threatening organ dysfunction caused by a dysregulated host response to infection." This places emphasis on organ dysfunction (measured by the SOFA score in humans) rather than the inflammatory response markers.

Veterinary medicine is moving in a similar direction, with increasing focus on:

• Multi-organ dysfunction syndrome (MODS) assessment as a prognostic and diagnostic tool
• Acute phase protein measurement — particularly C-reactive protein (CRP) in dogs as a biomarker of systemic inflammation
• Integration of organ dysfunction scoring alongside traditional SIRS criteria for more accurate diagnosis and outcome prediction

For AVE candidates, understanding both the current SIRS-based approach and the emerging organ-dysfunction framework demonstrates the breadth of emergency medicine knowledge that examiners expect.

Relevance to AVE Exam Preparation

Emergency medicine features prominently in the AVE clinical examination, particularly within the Small Animal Practice oral module. Candidates should be prepared to:

• Describe current CPR algorithms — including specific drug doses, compression techniques for different patient sizes, and defibrillation protocols
• Articulate what has changed — examiners value candidates who demonstrate awareness of why guidelines have evolved, not just what the current recommendations are
• Discuss post-ROSC care — initial stabilisation priorities after return of spontaneous circulation, including temperature management, blood pressure support, and neurological monitoring
• Recognise arrest rhythms — differentiate shockable (VF, pVT) from non-shockable (asystole, PEA) rhythms and describe the appropriate algorithm for each
• Apply emergency protocols under pressure — the Practical Anaesthesia station specifically assesses response to anaesthetic emergencies, including cardiovascular arrest

The ability to cite the 2024 RECOVER guidelines by name and describe the key changes from the 2012 version demonstrates the clinical currency that examiners look for in candidates seeking registration.

Clinical Pearls

• Speed matters: Begin compressions within 10-15 seconds of confirmed arrest — every second of delay reduces survival probability
• No high-dose epinephrine: Standard dose (0.01 mg/kg IV/IO) only, regardless of CPR duration. This is the most critical drug change and an easy exam question
• Know your patient's shape: Compression technique varies with body size and thoracic conformation — there is no universal hand position for all patients
• Vasopressin for refractory VF/pVT: Vasopressin (0.8 U/kg) is the first-line vasopressor when shockable rhythms persist after defibrillation
• Species matters for antiarrhythmics: Lidocaine (2 mg/kg) for dogs, amiodarone (5 mg/kg) for cats — this distinction is new and highly exam-relevant
• Defibrillate first: For shockable rhythms, deliver the electrical shock before administering any drugs
• Rotate compressors: Compression quality degrades within 2 minutes even when the rescuer feels fine — rotate every 2-minute cycle
• Atropine once only: If used, administer a single dose. Repeated atropine during CPR is no longer recommended