What better time to review heatstroke than now?
Heatstroke is a very serious concern, especially in the hot summer months. Providing good client education on this subject is especially important.
Heatstroke is a state of hyperthermia (106-109 F) resulting in multi-organ damage and in severe cases death. It occurs most frequently in dogs. Dogs with obesity, laryngeal disease, brachycephalic airway syndrome, or dogs that have been left outside or exercised in hot weather are at the highest risk.
When the core body temperature climbs above 107 for a prolonged period of time, renal tubular damage, gastrointestinal necrosis, cerebral edema or thrombosis, and liver and myocardial necrosis can occur.
Clinical symptoms of early heat stroke are severe dehydration, tachypnea, tachycardia, bounding pulses, and depression (the same as hypovolemic shock). As it progresses, neurologic symptoms can develop, petechial hemorrhages may be noted, or bloody vomit or diarrhea can occur.
Coagulation abnormalities are often seen and DIC (disseminated intravascular coagulation) may occur. The clotting factors are inactivated from the heat and the liver can no longer produce new clotting factors. Also, due to the organ damage that can occur, the liver enzymes may be elevated and azotemia (increased renal values) may be noted.
Even with treatment, the prognosis is extremely guarded. In severe cases the prognosis is generally poor.
1) The patient is cooled until the temperature is around 104-105º F. The temperature will continue to drop after cooling has stopped, and hypothermia can be dangerous in these patients. You can use cool water towels on the groin and axillary regions, and gently wipe the face or fur with a wet towel. A fan is very helpful. (A full bath is not usually recommended so you don’t overshoot the temperature)
2) Oxygen therapy
3) Place an IV catheter upon arrival, IV fluids should be started immediately. Typically they will receive up to ½ shock bolus (90 mL/kg is a shock bolus for a dog), then up to 2 times maintenance. This is highly individualized depending on severity of the patient and if they will also be receiving colloids and what the doctor recommends.
4) Monitor the ECG and Blood Pressure. If the blood pressure is low, hetastarch should be started (or fresh frozen plasma- see coagulation below); it is often started upon arrival. Serial monitoring of vital paramenters should be continued during hospitalization.
5) If a dog has an airway obstruction or laryngeal disease, they may require sedation and intubation.
6) Coagulation should be checked (PT/PTT). If the PT is elevated, plasma should be given. The PT will need to be monitored very closely and multiple plasma transfusions may be required until coagulation status has normalized.
7) Gastrointestinal protectants should be given (famotidine, sucralfate). Sometimes promotility agents are also needed (metoclopramide).
8) Urine output should be monitored very closely, indwelling urinary catheters are ideal in these cases.
9) Blood glucose monitoring is very important; hypoglycemia is very common and needs to be managed accordingly.
The client should be informed of prognosis and the plan for treatment by the doctor.