Exam 2: Heat Related Illness in Small Animals

describe the common history and signalment of heat injury

• high heat or lengthy exposure, strenuous activity, seizures

• brachy, thick coats, geriatrics, obese

what are the clinical signs of mild heat injury

• continuous panting or respiratory effort unresolved following cessation of exercise or removal from environment

• lethargy, stiffness, unwillingness to move

what is the suggested treatment for mild heat illness

• active cooling for hyperthermia

• rehydration

• supportive care for organ systems affected

• may be able to manage on the scene

• monitor for progression

describe moderate heat illness (heat exhaustion)

• progression of stage 1- no response to cooling or fluids

• hypersalivation, diarrhea, vomiting with no blood

• a single seizure

• episodic collapse with spontaneous recovery, no impaired consciousness

what is the suggested treatment for moderate heat illness (heat exhaustion)

• active colling f hyperthermic

• rehydration- may require IV

• supportive care for organs affected

• consider hospitalization to monitor progression

describe severe heat illness (heat stroke)

• progression of stage 2

• central nervous system impairment (ataxia, two or more seizures, profound depression, unresponsive, coma)

• liver or kidney dysfunction

• GI hemorrhage

• petechiae/purapura

what is the suggested treatment for severe heat illness (heat stroke)

• requires hospital care

• active cooling

• coag assessment

• neurological support

• IV fluids, blood glucose, electrolyte management

• resp support

• circulatory support

• GI support

• transfusion products

what defines heat stroke

• core temp >105.8F

• CNS dysfunction

• variable degrees of organ dysfunction

what are common exam findings of heat stroke

• variable temperature

• tachycardia, weak pulses, arrhythmia

• mentation depressed, varies

• ± petechiae

• vomiting. diarrhea ± blood

• ± hematuria

what diagnostics are typically done for heat injury

• CBC

• chemistry

• urinalysis (USG at minimum)

• Coag panel

• ± ECG

how does heat injury present on CBC

• hemoconcentration (increase Hct, TP)

• thormbocytopenia

• increased nRBCs

how does heat injury present on chemistry

• azotemia (up BUN, Creat)

• hypoglycemia

• hepatic insult (up ALT, AST)

• muscular insult (high increase in CK)

• electrolyte derangement possible but uncommon

how does heat injury present on UA and coag

• inappropriate USG, glucosuria, hematuria, casts possible

• increased PT, PTT

what are cooling measures

• lukewarm water dousing (evaporative)

• cold packs over major vessels (conduction)

• water immersion (conduction)

• IV fluids (internal conduction)

• fans (convection)

when should active cooling be stopped

when body temperature iis 103F

what cardiovascular support can be provided

• predominant hypovolemia

• fluids (crystalloids first up to shock dose bolus, then colloids if ineffective)

• avoid excessive fluid administration

• vasopressors if fluids ineffective at maintaining BP

what CNS support can be provided

• treat hypoglycemia if present, 2.5-5% dextrose

• seizure prophylaxis if indicated (Keppra 20-30mg/kg q8, Phenobarbital 2mg/kg q12)

• many signs resolve

• persistent? consider cerebal edema - mannitol 0.5-1.5g/kg

how can renal support be provided

• AKI not uncommon, but onset may be delayed

• fluid therapy to maintain urine output- crystalloids 1.5-2x maintenance to start, titrate

• consider urinary catheterization to monitor urine output

how can coagulation support be provided

• any PT/PTT elevation indicates treatment

• derangements are commonly delayed

• fresh frozen plasma 5-10mL/kg, be aggressive with decision to utilize FFP

how can gastrointestinal support be provided

• protective agents such as sucralfate and antacids (PPIs such as omeprazole better than H2 blockers)

• antibotics if blood diarrhea, sepsis (penicillin ± flouroquinolone)

• symptomatic treatment of vomiting

what is included in heat stroke monitoring

• neuro status

• blood pressure frequently then PRN

• blood glucose as frequent as needed

• coag- assess ongoing need for FFP (4hrs post presentation or 1-2hrs after transfusion, then q12)

• platelet count and Hct q24-48 (PCV/TS can be done q6-12)

• renal values daily

• urine output (catheter or body wight q6-12)

what is the general prognosis of heat injury

guarded depending on severity

35-40% mortality in dogs

what are negative prognostic indicators of heat stroke cases

• hemostatic dysfunction >12-24hrs

• MODS

• AKI

• >18nRBC/100 leuks

• Arrhythmia

• need for vasopressors

• persistent or progressive neurologic deficits

• hypoglycemia

• seizures