Veterinary Clinical Medicine-I (General and Systemic)

HYPOTHERMIA

• Hypothermia is a lowering of the body's temperature in animals or human beings.
• At a rectal temperature of less than 28 C (82 F), the ability to regain normal temperature is lost, but the animal will continue to survive if external heat is applied and the temperature returns to normal. It is important to observe and measure the vital signs: pulse, breathing, mental status and rectal temperature.
• To know the severity of hypothermia is valuable to decide the re-warming technique to be used for treatment.
• On the basis of body temperature, hypothermia can be classified as Mild (86 -89 F or 30 - 32 C), Moderate (71- 77 F or 22 -25 C) and Severe (32- 46.5 or 0 - 8 C). There are three rewarming techniques (Passive external, Active external, and Active internal) which should be used according to severity of hypothermia.
• When the skin or blood is cooled enough to lower the body temperature in non-hibernating animals, the metabolic and physiological processes slow down. In the hypothermic state, the oxygen need of cells, particularly neurons is greatly reduced, and the circulation can be stopped for relatively long periods.
• At a rectal temperature of less than 28 C (82 F), the ability to regain normal temperature is lost, but animal will continue to survive if external heat is applied and the temperature returns to normal. Hypothermia is a condition of general body cooling in contrast to frostbite, which is localized.
• A fall in body temperature can be due to accidental exposure to external cold, effect of drugs, or failure of internal temperature regulating mechanisms.
• The simplest way to determine whether the patient is hypothermic or not, is to assess body temperature by placing a bare hand against the skin (preferably in axilla or groin region) of the patient. If the skin feels warm, hypothermia is unlikely.
• Patients with cold skin should have rectal temperatures taken with a low reading thermometer.

What to expect in a hypothermic animal?

• As the body core temperature drops, more body systems suffer from the effects of cold.
• The signs and symptoms can assess the presence and severity of hypothermia.
• In the cold patient, a rectal temperature is one of the most important signs and is useful for assessing and treating hypothermia, however there is a tremendous variability in physiological responses at specific temperatures among individuals and species.
• Once it is established that an animal is hypothermic it is important to observe and measure the following most important signs: pulse (slow to none); breathing (slow to none); mental status (responsive to unconsciousness); cold skin; low rectal temperature.
• Severally hypothermic animals may have other problems, which are not easily detected. e.g. change in blood chemistry; irregular heart beat; dehydration; difference in temperature between deep body tissues and superficial body tissues.

Classification on the basis of severity

• On the basis of body temperature, hypothermia can be classified as Mild (86 -89 F or 30 - 32 C), Moderate (71- 77 F or 22 -25 C) and Severe (32- 46.5 or 0 - 8 C).

Management of a hypothermic animal

• The primary goals in the treatment and handling of a hypothermic animal are: keep the animal alive by warming, avoid any further exposure to cold, and then transport the animal to a site of complete veterinary care.
• In order to treat the hypothermic animal appropriately, one should first know that the animal is in fact hypothermic.
• If so, then the severity of hypothermia e.g. mild, moderate or severe.
• Once this is determined, one has to decide the re-warming technique to be used for treatment.