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I started to handle mice for my job and noticed that they tend to defecate and/or urinate when they are scared. The fear is induced by me, because I need a long time (due to inexperience) to grab the mice and then move them from one cage to a new one. My question is why?

I tried to look up literature for this behavior and there are different fear behaviors for different animals some shake in fear, some play dead but I could not find something for fear induced defecation. Therefore my question: What is the reason behind the "Fear induced defecation"?

I am especially interested into the neuroscience pathway behind it.

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    $\begingroup$ Just a guess - but this could be a mechanism to try to deter their attacker, the smell of urine and faeces may ruin the meal $\endgroup$
    – Simian
    Feb 15 '16 at 0:26
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    $\begingroup$ Just to share, if I'm nervous or am afraid, I feel like saying Hello to the bathroom. $\endgroup$
    – azam
    Feb 15 '16 at 18:53
  • $\begingroup$ Even if you're a pro, handling certain strains of mice for any length of time will cause them to void. It's not just you :) $\endgroup$
    – MattDMo
    Feb 16 '16 at 0:32
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If your mice are stressed or scared during those manipulations, as we can expect them to be, defecation can be a consequence of the "Fight-or-Flight response": in this situation, the organism try to focus its energy to act quickly, and a wave of specific neurotransmitters (noradrenaline in particular) is released. In consequence, mice's bladders relaxe, which cause them to urinate, the digestion stops, but the transit of the faeces in the colon is accelerated: they defecate.

This is all controlled by the activity of the sympathetic nervous system, which secrets acethylcholine and noradrenaline.

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