Hypothermia
Occurrence: Worldwide.
Age affected: Newborn (all ages).
Causes: Poor housing, lack of bedding, wet conditions,
starvation.
Effects: Shivering, pallor, cold skin, lethargy, prone to
infection, death.
Causes
Hypothermia occurs when pigs experience low environmental
temperatures and cannot maintain their body temperature at 38.5-39°C
(101.5-102.5°F). It is most serious in piglets aged 0-7 days, but can occur in
pigs of any age and can even kill adults of particular breeds in certain
circumstances. Piglets require environmental temperatures of 34°C or more for
the single neonate, or 25-30°C or more for the piglet able to huddle in order
to maintain body temperature. The piglet has no brown fat (used by mammals to
generate heat quickly) so the piglet cannot use fat to generate heat in cold
conditions. It must therefore use glucose and may be able to maintain both
blood glucose levels and body temperatures if able take in sufficient milk from
the sow. Any interruption of intake or too high a demand for energy (as in
piglets with low body weights or very low temperatures and wet conditions)
results in use of glycogen (animal starch) reserves from the liver. When these
are exhausted, the piglet’s body temperature begins to fall as does its blood
glucose. In piglets aged 7 days and more, gluconeogenesis (the formation of
glucose from proteins) can maintain the blood glucose level and prevent the
reduction in body temperature.
Mode of transmission
This condition is not transmissible, but will recur if pigs
are kept in the same conditions.
Clinical signs
Piglets in low temperatures huddle under lights or against
the sow, and older pigs huddle together. Single older pigs attempt to bury
themselves in bedding if available. Piglets suffering from hypothermia, have an
erect hair coat, they shiver and develop signs of hypoglycaemia such as
uncertain gait, supporting themselves by placing their noses on the ground and
spreading their hind limbs. More severely affected pigs rest on their abdomens
but eventually fall on their sides and develop convulsions which are
accompanied by slowing of the heart to 80 beats/minute, a decline in rectal
temperature, shivering and dullness. Death normally occurs 24-36 hours after
the commencement of the signs. Hypothermia in older pigs is less likely to lead
to death, but in all cases there is an increase in appetite, less live weight
gain per kg of feed, an increase in the length of the hair coat and a reduction
in body condition and fat thickness. Chilling may lead to failure to show
oestrus in sows and gilts, a decline in bodily condition which results in lower
litter sizes and to bluish ears and extremities. Vietnamese pot-bellied pigs
may die of hypothermia if maintained on high roughage diets and not protected
from sudden cold.
Huddling behaviour of piglets and older animals suggests that chilling is occurring, and burial in bedding and their appearance (bluish extremities, erect hair coats) may support the presence of hypothermia. The presence of piglets with difficulty in standing, convulsing or in a coma may also suggest hypothermia. Examination of these animals will reveal low rectal temperatures (down to 35°C). There may be dead animals. Hypoglycaemia alone should be eliminated as a cause of the condition in piglets and disease considered as a cause of mortality.Confirmation comes from an analysis of the environmental temperature over 24 hour periods using maximum and minimum thermometers or other ambient temperature recorders installed at min. Height
Postmortem lesions
The bodies of pigs which have died from hypothermia are often
in poor condition, and in older pigs may be covered in long hair. There may be
bluish discoloration of the extremities. Dead piglets are found to have empty
stomachs, low plasma glucose levels and low liver glycogen levels as in
hypoglycaemia.
Treatment and prevention
Hypoglycaemia treatments can also be useful for neonatal
piglets with hypothermia. Affected animals should be given intraperitoneal
injections of 15 ml of 5% glucose solution every 4-6 hours or oral glucose by
stomach tube and kept at a minimum of 30-35°C (85-95°F). If the sow is unable
to feed them, an artificial sow milk replacer should be given by stomach tube
initially or they should be fostered onto another sow. Reduction in draughts
and the provision or dry bedding and additional heating (either from heat
lamps, from underfloor or from heat pads) will also improve their chances of
survival. Orphaned or surplus piglets may be maintained in small groups in
incubators. In all cases, the environmental temperature should be raised to the
level appropriate to the age group. Where this cannot be done for the whole pen
or house, dry bedding will improve the pig environment and a dry, bedded kennel
area which excludes draughts will concentrate heat where required. Weaned pigs
should be given more food or food of higher energy density until the effects of
hypothermia on body condition are corrected.
Dr Parvinder Kaur
Veterinary officer
NRDDL,Jalandhar PUNJAB
9814652576
