Optimizing Electronic Von Frey for Mouse

Experimental Techniques
1

My project involves characterizing pain responses in mice following chronic constriction injury using Electronic Von Frey. We have been experiencing some challenges with the hand-held electronic Von Frey and animal enclosure from Ugo Basile during our experiments. I have learned a lot from those amazing posts on this forum from Alex but still have those problems as below.

For all experiments below, I let the mouse habituated in the enclosure 1-2 hours before the test.

  1. The probe is stiff and will inadvertently lift the mouse’s paw, influencing withdrawal force. The force application speed also affects the results. How should i correctly control it?

  2. I am using 8-10 weeks B6 mice. The mouse typically grips the bars instead of exposing the paws. It often requires a long waiting period for the mice to position their paws correctly for the mid-plantar surface stimulation. Are there any ways to improve this process?

  3. After a single stimulation, mouse tends to be alert and easily withdraw when they feel any stimulation. I waited for a couple of minutes between each trial so that it could reduce this touch-on response. However, I still have a problem with how to set the criteria between normal and touch-on responses.

I know this topic has been widely discussed. However, I do not find lots of references regarding using hand-held eVF and mice at the same time. I would really appreciated it to get some suggestions.

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Thanks for the kind words and discussion points Anthony.

  1. The probe is stiff and will inadvertently lift the mouse’s paw, influencing withdrawal force. The force application speed also affects the results. How should i correctly control it?

Yes I and others have seen this. The IITC stiff probe eVF in particular. For this reason, I abandoned using it and went with the MouseMet eVF which has very soft tip and low force range, and the lifting doesn’t happen.

  1. I am using 8-10 weeks B6 mice. The mouse typically grips the bars instead of exposing the paws. It often requires a long waiting period for the mice to position their paws correctly for the mid-plantar surface stimulation. Are there any ways to improve this process?

Yes, this happens. It’s annoying. Sometimes you can ‘stimulate’ them by tickling their bellies or paws to get them to move. But they also like to curl up their paw and hold it away from the floor, which also impedes testing. Gotta be patient, sadly.

  1. After a single stimulation, mouse tends to be alert and easily withdraw when they feel any stimulation. I waited for a couple of minutes between each trial so that it could reduce this touch-on response. However, I still have a problem with how to set the criteria between normal and touch-on responses.

Also an area of variability. Be consistent. I tried to be really rigid about it. Here is my protocol.
https://wustl.box.com/s/k828egjigetmn95k8afzms6b6ssi42jt