MouseMet Hot

We created MouseMet HOT as an alternative to the existing hotplate and tail flick tests for mice. With MouseMet EvF established and well validated we decided, in 2014, to draw on our 15 years experience with larger animals and to design a miniature probe suitable for mice and rats. The aim was to create a system which worked in exactly the same way as MouseMet EvF, for use in the same runs.

five topcat metrology HOT probes of different sizes
mousemet HOT transducer
mousemet hot and evf instruments with runs

A big 3Rs contribution:

The development was a success, with many of our existing MouseMet EvF customers taking up the thermal option to reduce the acclimation time and stress to the mice. The system is now in regular production. 

The probe tip is 2mm diameter and heats at 2.5°C/sec. It's mounted on a rotating arm so that, when brought into contact with the plantar surface, with a force of just 1g, heating is activated automatically. This force, we have found, provides consistent thermal transfer without premature withdrawal even when allodynia is present.

At threshold, the probe is removed and the thermal threshold displayed on the screen, along with a graph of the heating cycle.

graph from mousemet HOT instrument showing peak temperature
mousemet HOT probe tip 2mm diameter with flexible mount

Just as with MouseMet EvF, it's very important that the thermal probe stays in good thermal contact with the plantar surface, but without sliding or sctratching across the surface (which might elicit touch-on responses). So our HOT probe has a domed tip and is flexibly mounted to compensate for any side to side hand tremor during the test. It's mounted on a rotating, counterbalanced arm to maintain the 1g application force against the paw, even if the tester's hand shakes up and down.

And, like every other thermal threshold system that Topcat makes, there is a thermal cutout which can be set to the temperature required by your protocol.

The system was first trialled by the University of Queensland in 2015 where it produced baseline thresholds of 50°C on mice and detected both heat allodynia (at 43°C) and partial analgesia.

MouseMet HOT and MouseMet EvF are now used worldwide, Mousemet COLD is also in validation. And all in the same runs!

mousemet suite of instruments with stands
world map of mousemet installations