N1033787
1.0 Introduction
Hypothermia is known to cause negative effects on the cardiovascular, respiratory, endocrine, and immune systems( Khenissi et al, 2017), and occurs from either a decrease in heat production, increase in heat loss, or both( Oncken, Kirby and Rudloff, 2001). Heat loss can occur from four basic mechanisms:
• Convection – the transfer of heat from the body surface to air moving past the animal
• Conduction – the transfer of heat from the body to colder objects( e. g., table surfaces)
• Radiation – the exchange of heat between the body and objects in the environment that are not in contact with the skin
• Evaporation – when moisture that is in contact with the skin or respiratory tract dissipates into the air, taking body heat with it( Oncken, Kirby and Rudloff, 2001).
1.1 Hypothermia The normal body temperature for dog’ s ranges between 37.8 ° C – 39.2 ° C( Redondo et al, 2012). Hypothermia in dogs during general anaesthesia and surgery is very common, with studies showing that the prevalence of slight, moderate, and severe hypothermia was 51.5 %, 29.3 % and 2.8 % respectively, meaning that of the animals involved, 83.6 % became hypothermic( Redondo et al, 2012). This study looked at the prevalence of post-anaesthetic hypothermia in 1525 dogs and investigated its clinical predictors and consequences. The study was the first of its kind to investigate hypothermia in a large population, however used a classification of hypothermia which is considered more accurate for primary hypothermia. There are two classifications of hypothermia; primary( accidental) which occurs when an animal with normal heat production is exposed to a cold environment for an extended period, or secondary, which occurs when an illness, injury or drug therapy alters the animal’ s ability to thermoregulate( such as anaesthesia)( Brodeur et al, 2017). Oncken, Kirby and Rudloff( 2001) found that adverse effects occurred at higher temperatures in secondary hypothermia compared to primary, and so proposed a separate classification which has been widely accepted in veterinary patients( Brodeur et al, 2017). The scheme classifies the following:
• Mild hypothermia( 36.7 – 37.7 ° C),
• Moderate hypothermia( 35.5 – 36.7 ° C)
ANIM32126 – EBVN Project 9