Presumptive Acute Post‐Hypoxic Myoclonus Following Return of Spontaneous Circulation in a Cat and a Dog

OBJECTIVE: To describe the clinical presentation of presumptive acute post-hypoxic myoclonus in a cat and a dog after cardiopulmonary arrest (CPA). In people, acute post-hypoxic myoclonus is a transient focal, multifocal, or generalized rhythmic myoclonus that results from global hypoxic-ischemic brain injury and may be cortical or subcortical in origin, specifically brainstem-generated. Post-hypoxic myoclonus typically presents within 48 h of CPA while the patient is still comatose. Although this neurologic sign has historically been associated with a poorer prognosis, recent studies suggest that evaluation of its clinical characterization in conjunction with electroencephalographic features should be considered. CASE SERIES SUMMARY: We describe the cases of one cat and one dog that suffered CPA, underwent CPR, and experienced return of spontaneous circulation. Both cases developed presumed acute post-hypoxic myoclonus within 24 h of resuscitation, did not respond to antiseizure and sedative drugs, and were subsequently euthanized. NEW OR UNIQUE INFORMATION PROVIDED: Acute post-hypoxic myoclonus can occur in cats and dogs after CPA and successful resuscitation.