RESUMEN
CASE SUMMARY: This case report describes an acute reaction, thought to be vagally mediated, in two cats immediately following cystocentesis. Both cats were being evaluated for feline idiopathic cystitis and developed bradycardia, hypersalivation, urination and weakness after a blind cystocentesis. Both cats recovered uneventfully with supportive care. RELEVANCE AND NOVEL INFORMATION: A vagally mediated response may occur in cats after cystocentesis, which is a common procedure performed by veterinary professionals in cats. This response may be very profound and dramatic. Affected cats will likely make an uneventful recovery. This vagally mediated response to cystocentesis, though reported by word of mouth among veterinarians, has not been described in the literature. This is the first documentation of its occurrence in cats.