Fluids are the most important part of therapy, and sometimes all that is required to stabilize these patients pending results
of the ACTH stimulation test. The patients that present in crisis, often require shock doses (90 mls/kg) of IV replacement
crystalloids (0.9% NaCl or LRS are good first choice). I typically do not give the entire shock dose of fluids and then re-check, but instead give
20-30 ml/kg boluses over 30 minutes until desired effect. If the patient is hypoglycemic, they may need dextrose their maintenance
fluids after a bolus of 0.5 g/kg of dextrose has been given. Now that the patient is stabilized, the ACTH stimulation test
can be done. If steroids are deemed to be needed, then use 0.5 mg/kg DexSp (does not interfere with ACTH stimulation test)
Hyperkalemia will often resolve with fluid therapy alone, but if life threatening cardiac abnormalities occur then treatment
should be indicated. The three most common treatment options are: insulin (0.1-0.2 U/kg IV) to drive K+ into the cell (will
need to give 0.25-0.5 g/unit of dextrose concurrently to prevent hypoglycemia), bicarbonate (¼ - ½ of the calculated dose
=[0.3 x BW(kg) x base deficit]), calcium gluconate 10% (0.5 ml/kg IV, slowly over 15 minutes) does not alter the hyperkalemia
but is cardioprotective for about 30 minutes. This should allow for enough time to get them out of danger. The patient will
need to be started on longer acting glucocorticoids and mineralocorticoids when stable.
Most will be able to go home once they are eating, drinking, rehydrated, and electrolyte abnormalities have corrected. Make
sure the patient is making urine and hydration status has normalized. Due to electrolyte abnormalities it is always a good
idea to place them on continuous EKG. Monitor electrolytes (q4-8hr until normal), renal values daily, blood gas (q8hr), and
PCV/TS (daily). There has been reports of Pontine demyelination in people and dogs, when the hyponatremia is correct too rapidly.
These animals present in lateral recumbency, dull, rigid, and may have seizures.
Myxedema coma is a rare presentation of severe hypothyroidism. The presenting complaint may include mental dullness (even
stupor leading to coma), depression, dry hair coat, alopecia, and unresponsiveness. Physical examination may reveal non-pitting
edema of the skin, face, and jowls (tragic facial expression), hypothermia, bradycardia, hypotension and hypoventilation.
The myxedema is the result of the accumulation of mucopolysaccharides and hyaluronic acid in the dermis which bind water resulting
in increased thickness of skin. Myxedematous accumulations in the brain, along with hyponatremia, account for the neurologic
changes. Hyponatremia is due to an increase in total body water resulting from decreased renal excretion and tissue retention.
Biochemical testing may reveal low thyroid hormone concentrations, hypercholesterolemia, hyperlipidemia, hypoglycemia, hypoxia/hypercarbia
and hyponatremia. The mortality rate of myxedema coma is high due to lack of recognition of the syndrome. Treatment consists
of thyroid hormone supplementation and supportive care. The intravenous administration of thyroid hormone is recommended (Sodium
Levothyroxine 5 µg/kg q 12 hr). Appropriate supportive care may include fluid therapy (saline with dextrose), passive, slow
rewarming and potentially assisted ventilation. Improvement is usually noted within 8 hours. Once the patient is stable and
clinical signs improve, oral administration of thyroid hormone can be started.
Feldman EC, Nelson RW. Diabetic Ketoacidosis. In: Canine and Feline Endocrinology and Reproduction. WB Saunders, Philadelphia,
PA, pp 393-421, 1996.
Feldman EC, Nelson RW. Hypoadrenocorticism. In: Canine and Feline Endocrinology and Reproduction. WB Saunders, Philadelphia,
PA, pp 266-305, 1996.
Feldman EC, Nelson RW. Hypothyroidism. In: Canine and Feline Endocrinology and Reproduction. WB Saunders, Philadelphia, PA,
pp 68-117, 1996.
Hess R. Modern Concepts in Endocrinology. In: Multidisciplinary Systems Review, IVECCS 2006. pp 24-31.
Mazzaferro EM. Endocrine Situations That Make Our Job Challenging And Fun. In: Multidisciplinary Systems Review, IVECCS 2004.