Elephants Elephants - Wildpro - Twycross Zoo

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half the shoulder height distance (Kurt 1974). However, these ratios are not
always as accurate for captive zoo elephants which are frequently overweight
(see Section 3).
2.3 Physiology
A comprehensive account of the elephant’s physiology is outside of the scope
of this document. However, due to their immediate relevance to the
veterinary management of elephants, a few points deserve emphasis.
The normal body temperature of the elephant is between 36 and 37 oC.
Temperatures of 38 oC or above indicate a fever. As long as acclimatisation is
achieved progressively, elephants will adapt to a wide range of environmental
temperatures. A large mass:surface area ratio helps the elephant to tolerate
ambient temperatures of 4 oC or even lower, provided sufficient protection is
afforded from wind. However, elephants have a limited ability to lose heat,
and very high ambient temperatures and/or exposure to direct sunlight can
be problematic. Sweat glands are present throughout the skin, but are few in
number except for immediately above the toenails - thus the elephant relies on
heat loss through the ears, sheltering from the hot sun and evaporative losses
following bathing to avoid hypothermia. It is essential to provide shade and
water to bathe in at all times in hot climates.
The digestive system of the elephant is similar to that of the domestic horse. It
has a simple stomach and cellulose digestion takes place through microbial
fermentation in the large caecum and colon (and see section 2.7). The liver is
large, and there is no gall bladder. The presence of moderate amounts of sand
and stone in the intestinal tract is probably normal. Elephants defecate up to
20 times daily, with 4 – 6 boluses per defecation. Schmidt (1986) remarks that
elephants fed primarily on hay will have large roughly spherical faecal
boluses, composed of what looks like finely chopped hay and have 12-20
defecations per day, of 4-6 boluses per defecation (and see Section 2.7).
The resting heart rate of a standing adult elephant is between 30 and 40 beats
per minute (bpm) increasing by up to 25% when the animal lies in lateral
recumbency. (Healthy elephants in captivity can stand for long periods and
generally do not lie down for any length of time during the day). Lateral
recumbency also leads to increases in arterial blood pressure and a decrease in
arterial partial pressure of oxygen (PaO2) (Honeyman et al 1992), thus the
recumbent elephant may be at risk of developing hypoxemia and
hypertension. However, elephant blood has a greater affinity for oxygen than
that of other mammals.
Elephants are basically nose breathers – in other words, 70 % of their air intake
is via the trunk. The lungs are attached to the chest wall by fibrous connective
tissue which effectively eliminates any pleural space. This has been taken by
some to indicate that elephants rely more on diaphragmatic movement for
respiration than on costal movements (Todd 1913). Respiratory rates of adult
elephants are generally between 4–6 per minute, rising noticeably when
excited. Sternal recumbency can be dangerous especially in tired animals
(Namboodiri 1997).