2024 RECOVER Guideline Key ALS Updates

By Alison Allukian, DVM
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March 2025

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Introduction

The RECOVER (Reassessment Campaign on Veterinary Resuscitation) initiative is a collaborative effort to improve outcomes for dogs and cats experiencing cardiopulmonary arrest (CPA). Spearheaded in 2010 by a group of veterinary specialists, it focuses on two primary objectives: to devise clinical guidelines on how to best treat cardiopulmonary arrest (CPA) in dogs and cats and to identify knowledge gaps where more research is needed. These knowledge gaps are essential targets for future studies and clinical trials to refine and improve CPR practices in veterinary medicine. The RECOVER committee developed standardized, evidence-based clinical CPR guidelines that were first published in 2012 in the Journal of Veterinary Emergency and Critical Care, marking the first consensus-based guidelines for small animal CPR. A 2024 update was released, reflecting new research, expert opinions, and clinical insights over the past decade.

Key Updates in the 2024 RECOVER ALS Guidelines

• Epinephrine Administration: Historically, high-dose epinephrine (0.1 mg/kg) could be considered after prolonged CPR (i.e., CPR > 10 minutes duration) because of evidence that this dose was associated with a higher rate of return of spontaneous circulation. Despite this evidence, no consistent long-term survival or functional outcome effect was demonstrated. Although high-dose epinephrine has been associated with increased frequency of ROSC in people, it has also been associated with decreased frequency of survival to discharge and with worse neurologic outcomes. The new recommendation is that high-dose epinephrine should no longer be considered at any time during CPR in dogs and cats. Instead, a standard dosing of 0.01 mg/kg should be administered every three to five minutes.

• Atropine during CPR and dosing interval: Atropine is recommended to prevent CPA in patients with bradycardia secondary to high vagal tone. The RECOVER 2012 CPR Guidelines also suggest that it can be considered during CPR in dogs and cats with nonshockable arrest rhythms, particularly in animals with high vagal tone as a suspected trigger for arrest.

However, atropine has been removed from human CPR guidelines, and the evidence is primarily supportive of atropine as part of the treatment of severe bradycardia, rather than as part of CPR. The RECOVER committee investigated whether atropine is beneficial in dogs and cats with high vagal tone preceding cardiopulmonary arrest (CPA).

The evidence surrounding the potential benefit of atropine during CPR for patients with nonshockable arrest rhythms is conflicting and extremely limited. Although the majority of studies showed no difference in outcomes in these patients with administration of atropine, one observational study in humans demonstrated an association between atropine administration. It reduced the likelihood of survival to discharge, and one experimental dog study showed a potential benefit. The RECOVER committee found convincing evidence that higher doses of atropine were associated with worse outcomes than placebo control.

The RECOVER guidelines recommend the use of atropine (0.04 mg/kg IV or IO) in dogs and cats with bradycardia causing hemodynamic compromise to attempt to prevent progression to CPA. They also recommended against administering repeated doses of atropine during CPR for dogs and cats with non-shockable arrest rhythms and that, if given, it should be administered as early as possible.

• Defibrillation Protocols: There are two types of defibrillators available. Monophasic defibrillators deliver current in one direction between the paddles and across the patient’s chest. In contrast, biphasic defibrillators deliver current in one direction before reversing polarity and delivering a current in the opposing direction. Biphasic defibrillators have been shown to successfully defibrillate patients at a lower energy output, leading to less myocardial damage, and are recommended over monophasic devices. Dosing for monophasic defibrillators begins at 4 to 6 J/kg, whereas biphasic defibrillation dosing starts at 2 to 4 J/kg. Multiple studies show improved neurologic outcome, survival to discharge, and ROSC with biphasic defibrillation compared to monophasic. Many experimental studies in pigs and dogs show improved hemodynamics and decreased myocardial injury with biphasic. For patients with shockable rhythms, if a shockable rhythm persists after the initial defibrillation, it’s recommended to double the defibrillation energy dose starting with the second shock and maintain this dose for subsequent shocks.
• Antiarrhythmic protocols: Antiarrhythmic drug therapy is an adjunctive treatment for shockable rhythms. Antiarrhythmic medications should also be considered, such as amiodarone for cats and lidocaine for dogs. ​ Current veterinary and human CPR guidelines suggest that lidocaine may improve outcomes in patients with refractory shockable rhythms that do not respond to initial defibrillation. Further evidence in dogs suggests that lidocaine may increase the defibrillation threshold when a monophasic defibrillator is used. In contrast, a more recent study in pigs indicated that this increase in defibrillation threshold does not occur with biphasic defibrillation.

The new guidelines recommend that lidocaine be administered to dogs with pulseless ventricular tachycardia or V-fib after an initial shock dose or amiodarone if lidocaine is not available. They also recommend against lidocaine in cats and recommend amiodarone instead. The use of intravenous lidocaine in cats is controversial since they have a reported sensitivity to its central nervous and cardiovascular effects.

CPR Drug Dosing for Dogs and Cats

This chart summarizes the doses of drugs that should be used during CPR. As part of CPR preparation, a drug dose chart should be in plain view in the hospital’s ready area.

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References

Jacob Wolf DVM, DACVECC, Gareth J. Buckley MA, VetMB, DACVECC, DECVECC, Elizabeth A. Rozanski DVM, DACVIM, DACVECC, et al. 2024 RECOVER Guidelines: Advanced Life Support—evidence and knowledge gap analysis with treatment recommendations for small animal CPR. 26 June 2024.