Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: FuzzyUK on 05/11/2009 22:00:33
-
I saw this on another message board:
"I ran over the cat and was horrified. I stopped the car and looked (for some unknown reason) into my rearview mirror. The body jerked several feet up into the air (past the distance I could see in my mirror), about four or five times, yet the body was lifeless. The head and limbs barely moved. What could make the body jerk so high like that? Then it came to me. The cat was trying to free himself from the dead body. Of course, I checked the cat - it was stiff and most definitely dead ...."
This person claims rigor mortis sets in immediately with cats. I disagree. Are there any vets around that might like to comment?
[MOD EDIT - PLEASE PHRASE YOUR THREAD TITLES IN FUTURE AS QUESTIONS, IN LINE WITH OUR FORUM POLICY. THANKS]
-
If the feline was stiff immediately after the collision it may have already been terminated by another motorist some time earlier.
-
Rigor mortis manifests in cats at the same rate that it occurs in all mammals - after a few hours. When this occurs, muscles progressively stiffen until the body becomes stiff as a board. This state persists for 12-20 hours before the body becomes flaccid again and also begins to decay.
The cause of rigor mortis relates to energy supply in muscles. Muscles actually use energy to relax, which they do by breaking associations between the actin and myosin filaments that make up muscle. When an animal first dies, muscles are biochemically still metabolically active and so they have a ready supply of energy and can break any links between actin and myosin.
But, as time passes and cells run out of energy, this can no longer be done and the muscles "lock up". This is rigor. After another 10-15 hours has passed in this state, however, the cells and the contractile proteins begin to break down, which causes the return to a flaccid state.
In the question above the cat apparently jumped into the air several times despite the fact that it was dead. The most likely explanation is spontaneous muscle activation initiated by waves of nerve discharges in the brain and spinal cord which can be triggered by physical trauma or as a consequence of oxygen deficit.
Chris