Effect of Manual Restraint and Visual Security on Heart Rate in Dyeing Poison Dart Frogs (Dendrobates tinctorius azureus) and Leopard Frogs (Lithobates pipiens)

Abstract

Frogs are popular exotic pets and research subjects. Manual restraint is routinely used for basic procedures in frogs, including examination and sample collection, but there is little information on its physiologic effects in amphibians. Previous literature suggested that amphibians lack emotional responses and, therefore, consciousness, based upon an inability to elicit stress tachycardia with gentle handling. To determine if manual restraint results in a stress tachycardia in frogs, 10 poison dart frogs (Dendrobates tinctorius) and 8 leopard frogs (Lithobates pipiens) were manually restrained and heart rate (HR) recorded at both the pectoral girdle and pelvic patch using a Doppler flow probe. Frogs were randomly placed in one of two (opaque versus translucent) types of plastic containers for 22 min and HR measured every 2 min through the bottom of the container using the frogs' pelvic patch area. Frogs were then removed from the container, manually restrained again, and HR recorded. Heart rate decreased significantly after the frogs were placed in the containers following manual restraint, and increased significantly for the second restraint period. There were no significant differences in measured HR between anatomic sites (pelvic vs. pectoral) or container types. Contrary to previous descriptions, these results demonstrated that, similar to other mammal and reptile species, frogs demonstrated stress tachycardia during manual restraint, and, therefore, clinicians and researchers should be mindful of induced stress when restraining amphibians.