From:
RRC
Date: 2001-03-29 08:16:00 UTC
Subject: Re: Morbid questions
Hi TLE!
Those are good questions, but accurate answers are lacking. I'll give it
a shot.
>When a ferret dies, how long before the body becomes ice cold?
The body will never become ice cold unless the ambient temperature is
"ice cold." Fresh dead bodies (of ANY type) will initially lose (or
gain) temperature until they reach that of the surrounding environment.
So if your house is 70 F, the ferret will stabilize at about 70 F. There
are mathematical formulae which can be used to roughly estimate the time
of death of humans (based on cooling rates), but I know of none which
could be used to do the same thing for ferrets. There are some
complicating factors in ferrets; they have different body proportions
than typical mammals, so they lose body temperature at a faster rate
(based on surface area to volume ratios). This means a dead ferret will
cool faster than a dead kitten of the same weight. Another complicating
factor is the initial temperature of the ferret AT death; some disease
processes can throw off the ferret's internal thermostat, increasing or
decreasing the body temperature (I have had several ferrets which have
become extremely hyper- and hypothermic prior to death). This
temperature change will greatly influence the time the body takes to
cool to the surrounding environment. When the tissues begin to decay and
bacteria and insects begin to consume the remains, the body temperature
will increase over that of the surrounding environment. The worst
problem is the small size of the ferret; temperature loss is
proportional to body mass, so tiny animals lose temperature much faster
than larger ones.
The bottom line is, while mathematical formulae can be devised to
estimate the time of death of a ferret, because of the rapid heat loss
and various complicating factors (metabolism, muscle pH, etc.), the
formulae would only be useful for very short periods of time, perhaps
only a few hours. It is likely the range of error would exceed the range
of estimation, making a guess just as accurate as any formula determination.
>Is this before or after rigor sets in?
>How long before rigor sets in?
>How long before they come out of rigor?
Rigor is an autolytic phenomenon of muscles because of a lack of ATP. As
the sarcoplasmic reticulum of muscle cells lose integrity, calcium ions
flood the sarcomere (the contractile part of the muscle), unblocking
binding sites on the actin, allowing the actin molecules to bind via a
cross-arm extending from the myosin. As the cross-arm retracts, the
actin is pulled along the thick myosin fiber. Because the sarcomeres are
joined end-to-end, when this action is summed over the length of the
muscle, it shortens and becomes rigid. This is the same thing that
happens when you contract your muscles during work. Normally, ATP-fueled
ionic active transport mechanisms pump the calcium back into the
sarcoplasmic reticulum, which allows the actin/myosin complex to detach
and relax. But in dead ferrets, oxygen/glucose driven metabolism ends,
the Krebs Cycle is broken and ATP is no longer produced. The ion pump no
longer functions and the muscles remain rigid. Rigor ends as autolysis
progresses, causing a breakdown of the myofibrils in the muscle tissue.
The actin molecules become detached from the ends of the sarcomere,
which allows the contractile units to lengthen.
There are two factors which greatly influence the onset and duration of
rigor; the metabolic state of the individual and the ambient (or
surrounding) temperature. Cold temperatures cause rigor to progress more
rapidly and last longer, while warm temperatures delay rigor. In very
warm areas, rigor may not develop fully. Rigor progresses faster if the
death is associated with heavy exercise or high body temperatures
(related to lactic acids in the tissues). In smaller creatures, rigor
progresses and resolves rapidly because it is greatly influenced by
cooling rates and proportions of skeletal muscle.
Rigor typically has an onset between 2-6 hours after death in humans,
and resolves 24-84 hours later. I do not know of a study which has
documented the times for ferrets, although I would expect them to be
much sooner, perhaps from 0.5 to 2 hours, and lasting from roughly 12 to
48 hours (based on size, cooling rates, and metabolism). Because ferrets
are so small, have such high metabolic rates, and are so sensitive to
environmental influences, even this guess is probably so full of error
as to render it unusable.
>Then do they go back in and if so how long before?
Technically, once autolysis has caused a deterioration of the
myofibrils, rigor cannot set back in. However, if the tissues are
dehydrated, some tissues may stiffen, mimicking rigor.
>Answers to these questions may help us with time frames on deaths when we
>are not home with the little ones.
To do this with ferrets would be very difficult and I'll explain why. In
humans, these times have been worked out with a great deal of precision
BECAUSE humans are so large and have a surface area to volume ratio
which favors heat retention. This means rigor takes some time to begin,
progresses slowly, and resolves slowly. This gives the investigator a
wide window of time for rigor to take place, reducing the importance of
error (12 hours ± 2 hours). However, ferrets are very small and have a
surface area to volume ratio which is much less effective at preserving
temperature. This gives the investigator a very short window of time,
increasing the importance of error (3 hours ± 2 hours). As the window of
time approaches the degree of error, the measurement loses precision and
accuracy, rendering the value no more than an educated guess. As each
complicating factor is added, the value decreases in precision and
accuracy until it has no real value at all.
I am not saying such measurements would be useless; with care and a good
data base the values for an animal as hard to estimate as the ferret
could be established. But because the ferret is so sensitive to various
environmental (and metabolic) factors, even good estimates would have
minimal accuracy.
Sorry I couldn't help more.
Bob C
>From: Troy Lynn Eckart <sprite@k...>
>Subject: Morbid questions
>
>All of the questions refer to normal house temperatures (68-74).
>
>When a ferret dies, how long before the body becomes ice cold? Is this
>before or after rigor sets in?
>
>How long before rigor sets in?
>
>How long before they come out of rigor?
>
>Then do they go back in and if so how long before?
>
>Answers to these questions may help us with time frames on deaths when we
>are not home with the little ones.
>
>Hugs to all. tle
>Troy Lynn Eckart