Identification of newborn rats by tattooing

Abstract

Pups were identified by toe clipping or tattooing the plantar surface of the paws on day 4 after delivery. Their growth, maturation, and reproductive capability were not affected by either identification method. In the toe clipping group, however, the duration until fall in the suspension test was significantly shortened, indicating that this identification method may not be suitable for some behavioural tests. The clipping also disturbs the skeletal investigation of toes and is not recommended from the view point of animal welfare. Palm tattooing, on the other hand, satisfies the fundamental requirements for long-term identification of rats.

Co-Housing Rodents with Different Coat Colours as a Simple, Non-Invasive Means of Individual Identification: Validating Mixed-Strain Housing for C57BL/6 and DBA/2 Mice

“…ear notching [3] or toe clipping [4]), or the addition of permanent identification tags (e.g. tattooing [5] or micro-chipping [6]). Methods are constantly being refined and improved (e.g.…”

“…However, some caution is needed here: there is a current lack of knowledge about the perception of pain in young rodents [15], and objectively assessing low-moderate pain in mice is also recognised as difficult [4], [16]. Furthermore, evidence from rats indicates that toe-clipping can impair later performance in certain behavioural tasks, such as the grip suspension test or a swimming task [5]. Toe-clips and ear-notches may also be hard for researchers to detect without very close proximity or handling, especially in animals within their home cages and/or under red light, in turn raising dangers of observer effects and making these marks inappropriate for identification in video recordings [8].…”

“…These methods require specialized equipment and some technical skill to administer. Traditional ear tattoo methods caused a significant acute increase in heart rate and blood pressure in rats (comparable to ear notching) [7], although apparently no long-term effects on growth, behaviour, or sensory-motor function [5], [14], [17]. Microchips are generally injected into the subcutaneous region of the dorsal surface of the rodent, sometimes with anaesthesia (e.g.…”

Techniques of Experimentation

“…Tattoos may include various letter/number combinations, common with larger species such as rabbits and nonhuman primates, or colored dot patterns (Iwaki et al, 1989). The tail and feet are the best sites for tattooing rats and mice (Fig.…”

Rapid Genotyping of Animals Followed by Establishing Primary Cultures of Brain Neurons

“…Tattooing newborn animals is advantageous because it can be carried out rapidly and lasts for much of the animal's life 7,[22][23][24][25] . Tattooing on the paw pads can be better than toe clipping 23 with respect to preserving testable behaviors, for example in suspension or gripping 22,26 , although some studies have not noted such deficiencies (e.g., 25 ). There were no instances of mothers rejecting or cannibalizing pups after tattooing.…”