Relationship between rectal temperature measured with a conventional thermometer and the temperature of several body regions measured by infrared thermography in fattening rabbits. Influence of different environmental factors

Abstract

[EN] In clinical examination of rabbits, the temperature is usually recorded with a digital thermometer introduced rectally, an invasive procedure that could cause handling stress. The aim of this study was to assess body temperature using infrared thermography (IRT) in four areas of the rabbit’s anatomy: eye (ETT), outer ear (OETT), inner ear (IETT) and nose (NTT), and then validate it as an alternative measure to rectal temperature (RT) assessed with a conventional thermometer. Temperature samples were taken twice a week from 48 weaned rabbits of Spanish Common Rabbit breed during a 38-d fattening period. The factors considered were: doe from which the rabbits came (8 does), weeks of fattening period (4 to 5 wk), batch (3 periods of the year: April-May, June-July and January-February) and group size (cages with 1 to 7 rabbits). On average, the results were an RT of 38.48±0.02 °C; ETT of 37.31±0.05 °C; OETT of 29.09±0.26°C; IETT of 30.53±0.251 °C, and NTT of 33.29±0.11 °C (mean±se). Moderate, statistically significant positive correlations (P<0.001) were observed between RT and temperatures measured with infrared thermography (IETT, OETT, ETT and NTT), both in general (0.39 to 0.49) and intraclass (0.36 to 0.39), based on the batch, group size, week of fattening period and doe. The thermographic measurements which showed the highest correlation with RT were OETT and IETT. We also studied the effects that could influence the temperature variables evaluated by IRT and RT within each batch: for each week of the fattening period, for the group size and for the doe effect. We found significant differences (P<0.001) between weeks within the batch, with a tendency for the temperature of the rabbits to increase as the fattening period progressed. The doe effect (within the batch) did not show, on the whole, any statistically significant differences within batches. On the other hand, we did observe a trend towards higher temperatures as the group size increased. In conclusion, infrared thermography is an effective tool for body temperature assessment and correlates closely with RT, with IETT appearing as the best reference point for taking body temperature in fattening rabbits. Infrared thermography appeared as a suitable alternative to RT for body temperature assessment in rabbits, thus avoiding handling stress.