Thermoregulation in Dogs
with permission from
Allsorts' Dog Pictures
|Photographed by Robin
and Harold Winter.
Used with permission from Narnia Kennels.
Effects of Bed Rest on Humans
In humans prolonged bed rest causes a headward redistribution of fluids, vascular fluid-electrolyte shifts, decreases in vascular and total body water, reduction of muscle mass, increased fat content, negative balances of calcium and nitrogen, and changes in glucose tolerance. Diminished work capacity and increased rectal and esophageal temperatures are seen in bed-rested humans during exercise.
Restricted Activity in Dogs
Restricted activity in dogs has an effect on their thermal and metabolic responses to exercise. Confinement for eight weeks to cages limiting activity to standing, laying down, and slight forward and backward movement had the following effects on dogs:
Exercise training in dogs can have an effect on their physiological responses to exercise. After eight weeks of confinement an eight week training program consisting of an hour of exercise a day, six days a week had the following effects on dogs:
Dogs appear to become exhausted during exercise when their rectal
temperatures reach a certain level. This suggests that hyperthermia
due to exercise may be a major limiting factor of exercise performance
in dogs. In one study dogs were able to exercise for the longest
amount of time before exhaustion and use the highest amount of available
muscle glycogen during exercise after eight weeks of exercise training.
The dogs exercised for the least amount of time before exhaustion and used
the least amount of available muscle glycogen during exercise after
eight weeks of restricted activity. A possible cause of the decreased
use of muscle glycogen after restricted activity is that hyperthermia caused
exhaustion before muscle glycogen use was maximized. The differences
between rates of increase in rectal temperature in dogs after restricted
activity and after exercise training appear to cause differences in exercise
endurances because of the affect of rate of rectal temperature increase
on hyperthermia. Thus, dogs with higher rates of increase in rectal
temperature can endure less exercise than dogs with lower rates because
hyperthermia sets in more quickly as rate increases (Nazar
et al. 1992).
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