Practical rat tickling: Determining an efficient and effective dosage of heterospecific play

• Published in: Applied animal behaviour science 2018-11, Vol.208, p.82-91
• Main Authors: LaFollette, Megan R., O’Haire, Marguerite E., Cloutier, Sylvie, Gaskill, Brianna N.
• Format: Article
• Language: English
• Subjects: Animal care; Animal handling; Animal models; Animal welfare; Anxiety; Approach behavior; Cages; Corticosterone; Data processing; Dosage; Handling; Human-animal interaction; Injection; Larynx; Positive affective states; Rats; Rodents; Stress
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/j.applanim.2018.08.005

•Rats were tickled for 3 frequencies (1, 3, 5 days) & 3 durations (15, 30, 60 s).•Across all measures, tickling duration did not affect any results.•Rats tickled for 3 & 5 days made more positive calls before & during tickling.•Rats tickled for 3 & 5 days show more play & less inactivity before tickling.•Results suggest the most efficient & effective dosage is 15 s for 3 days. Laboratory rats may experience stress during handling which can reduce their welfare. Rat tickling, a handling technique that mimics aspects of rat rough-and-tumble play, has been found to induce positive affect based on production of 50-kHz ultrasonic vocalizations (USVs). However, current protocols for rat tickling are time-intensive, making implementation difficult. Our objective was to determine a time-efficient and effective dosage of rat tickling that could be practically implemented in the laboratory. We hypothesized that affect and handling can be improved by short, daily doses of tickling within a 5-day work week. Long-Evans rats (N = 72) of both sexes, housed in pairs were sampled. Each pair was randomly assigned a tickling duration (15, 30 or 60 s per rat) and frequency (1, 3, or 5 days). After the final day of tickling, rats were tested for ease of, and reaction to, handling via an intraperitoneal injection of saline following a tickling session for their assigned duration. On test day, we measured production of USVs, home cage behavior (60 min before/after testing), approach behavior (30 s before/after testing), and fecal corticosterone. Periods before and after testing measured anticipatory and reactionary responses, respectively. In cage behaviors included social play, activity, and location. Approach behaviors included indicators of fear or anxiety such as rearing, location, and contact with the hand. Data were analyzed using general linear models. We found that 3-day rat tickling was most efficient and effective as it produced a higher rate of 50-kHz USVs before and during tickling (p