Blood collection from the sublingual vein in mice and hamsters: a suitable alternative to retrobulbar technique that provides large volumes and minimizes tissue damage.

Blood examination is a key element in studies of laboratory animals. In rodents, retrobulbar venous plexus puncture is a commonly used method for obtaining a blood sample. Although this technique yields large volumes of blood, the disadvantage is that it can lead to severe tissue damage. The aim of the present study was to develop the puncture of V. sublingualis as a suitable alternative technique for drawing blood in mice and other rodents. In rats, this method has been established for collecting large blood volumes. During the first part of the study, the sublingual bleeding technique was developed for use in mice and hamsters. Guinea pigs, however, do not have a sublingual vein; therefore, in this species the method is not possible. In the second part of the study, retrobulbar and sublingual methods were compared using male CD-1 mice. When compared with the retrobulbar method, sublingual venepuncture showed less tissue destruction in mice, with a decreased mean severity in the histological examination. In conclusion, sublingual venepuncture can be recommended as a suitable, alternative blood collection technique, because of the reduced risk of tissue damage in mice and hamsters.

Should laboratory mice be anaesthetized for tail biopsy?

Tail biopsies are routinely taken to genotype genetically modified mice. However, the effect of this procedure on the wellbeing of the animals has rarely been investigated. Thus, it has not yet been clearly demonstrated to what extent the mice suffer from tail biopsy (TB) and for how long. The aim of our study was to assess the impact of a single TB on the physiological and behavioural parameters of adult mice and to investigate whether or not anaesthesia can be beneficial. Body weight (BW) curves, daily food/water consumption and telemetric measurements of heart rate, body core temperature, and locomotor activity were recorded for three days following TB, both with and without anaesthesia with methoxyflurane (MOF) or diethylether (ether). Additionally, the impact of anaesthesia alone was characterized. TB without anaesthesia induced an increase in heart rate and locomotor activity for 1 h. Body core temperature was elevated for 2 h. In contrast, heart rate was increased for up to 4 h after anaesthesia. Body core temperature remained altered for up to 20 h after exposure to ether and for 44 h after exposure to MOF. BW was slightly reduced after MOF. Cases of death occurred exclusively under ether at a rate of 7%. Our results indicate a short-lived impact of a TB, whereas anaesthesia with either MOF or ether induced remarkable alterations in the parameters analysed. In conclusion, these types of anaesthesia did not improve mouse wellbeing following tail biopsy.

The physiological and behavioral impact of sensory contact among unfamiliar adult mice in the laboratory.

Housing mice in the laboratory in groups enables social interaction and is the way a laboratory should house mice. However, adult males show reciprocal aggression and are therefore frequently housed individually. Alternatively, a grid divider, which allows sensory contact by sight and smell but prevents fighting and injuries, can separate mice within 1 cage. This study examined the influence of this housing method on various physiological and behavioral parameters. Adult male mice housed for 10 days with sensory contact to an unfamiliar male displayed significant increases in heart rate (HR), body core temperature (BT), and motor activity (ACT). Furthermore, the mice suffered impaired nest-building behavior and significantly reduced body weight. Conversely, males housed in a similar manner with a female companion showed only a transient elevation of ACT, BT, and HR. Although no clear beneficial effect of housing males with sensory contact to females was evident, this study could not exclude it. On the other hand, housing of mature males in this way leads to sustained detrimental alterations of physiology and behavior, thus implying severe impairment of animal well-being.