Marked for life? Effects of early cage‐cleaning frequency, delivery batch, and identification tail‐marking on rat anxiety profiles

Abstract

Daily handling of preweanling rats reduces their adult anxiety. Even routine cage-cleaning, involving handling, reduces adult anxiety compared with controls. Cage-cleaning regimes differ between animal breeders, potentially affecting rodent anxiety and experimental results. Here, 92 adult male rats given different cage-cleaning rates as pups, were compared on plus-maze, hyponeophagia, corticosterone, and handling tests. They were pair-housed and half were tailmarked for identification. Anxiety/stress profiles were unaffected by cage-cleaning frequency, suggesting that commercial-typical differences in husbandry contribute little variance to adult rat behavior. However, delivery batch affected some elevated plus-maze measures. Also, tail-marked rats spent three times longer on the plusmaze open arms than their unmarked cagemates, suggesting reduced anxiety, yet paradoxically they showed greater chromodacryorrhoea responses to handling, implying increased aversion to human contact. A follow-up study showed that rats avoided the odor released from the marker pen used. Thus, apparently trivial aspects of procedure can greatly affect experimental results.

Effects of cage-cleaning frequency on laboratory rat reproduction, cannibalism, and welfare

“…Furthermore, in a follow-up study, we found no significant effects on pup handleability or anxiety profiles in adulthood (Burn et al, 2008). However, we found that cannibalism increased with more frequent cage-cleaning, which is consistent with the small-scale study by Cisar and Jayson (1967), and with common perception (e.g.…”

“…Here and in a follow-up study (Burn et al, 2008), we found no clear benefits of frequent cagecleaning to breeding rats, but it did increase the likelihood of cannibalism, and the cleaning process itself might have triggered parturition. We would therefore recommend that cages are not cleaned during the last few days of pregnancy (possibly avoiding premature induction of birth) or the first 2 days following birth (avoiding acute early disturbances).…”

The pilocarpine model of temporal lobe epilepsy: Marked intrastrain differences in female Sprague–Dawley rats and the effect of estrous cycle

“…In addition to genetic differences between outbred SD or Wistar rats from different vendors or locations of the same vendor, intrastrain differences can also be due to housing and handling conditions at the vendor during development of the animals [13,15,[36][37][38]. In the present and previous studies in SE models by our group, all rats were kept under the same controlled environmental conditions once they arrived in our laboratory.…”

A guide to defining and implementing protocols for the welfare assessment of laboratory animals: eleventh report of the BVAAWF/FRAME/RSPCA/UFAW Joint Working Group on Refinement

“…Handling is stressful for many animals, which can affect both animal welfare and the scientific data. 16 Observing animals following handling (for example, to record body weight) can facilitate observing some relevant behaviours, such as the postsurgical behaviours outlined in section 2.5.2, and reduce the time needed for the assessment.…”