MAINTENANCE TREATMENT
Once a patient's hemodynamic parameters and electrolytes have stabilized and the patient is eating and drinking, initiate
maintenance therapy.
Glucocorticoids
Table 5: Maintenance Treatment of Dogs with Hypoadrenocorticism*
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Since mineralocorticoid deficiency alone is rare, almost all dogs with hypoadrenocorticism require glucocorticoid supplementation.
Prednisone or prednisolone is used to maintain glucocorticoid replacement and is initially started at 0.2 mg/kg daily (Table 5); adjust the dose based on clinical signs.3
Table 6: Glucocorticoid and Mineralocorticoid Properties*
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Other oral, short-acting glucocorticoids may be used as well, and you should adjust the dose based on the relative potency
of that particular glucocorticoid (Table 6). For example, dexamethasone has about seven times more glucocorticoid activity than prednisone does. Thus, you would divide
the prednisone dose by seven to determine the equivalent dexamethasone dose. Avoid long-acting depot formulations of injectable
glucocorticoids because of varied serum concentrations and durations of action. The dose of glucocorticoids should be at least
doubled during periods of stress such as grooming and medical evaluation.3,4 Clinical signs such as anorexia, lethargy, vomiting, or diarrhea indicate inadequate glucocorticoid administration.1
Mineralocorticoids
If mineralocorticoid deficiency causing hyperkalemia and hyponatremia is present, institute treatment with desoxycorticosterone
pivalate (DOCP) (Percorten—Novartis Animal Health) or fludrocortisone acetate (Table 5).
DOCP. DOCP is a long-acting injectable mineralocorticoid given at a dosage of 2 mg/kg intramuscularly or subcutaneously about every
25 days.4,9,29 However, the duration of action can vary from 14 to 35 days,13 so adjust the dose and administration frequency as needed; many dogs require an increase in dose over the first six to 12
months after diagnosis.3 Monitor serum electrolyte concentrations 14, 21, and 28 days after DOCP administration and then as needed to determine DOCP's
duration of action and efficacy.3 Typically, adjusting the dose or frequency by 10% will alleviate electrolyte abnormalities.
Many veterinarians prefer DOCP over fludrocortisone since DOCP is a long-acting injectable medication that circumvents problems
with day-to-day owner compliance and drug bioavailability. DOCP has negligible glucocorticoid activity and should always be
administered in conjunction with glucocorticoid therapy.13
Fludrocortisone. Fludrocortisone is a short-acting oral mineralocorticoid and is administered at a daily dose of 0.01 to 0.02 mg/kg.1,3,4,9 Similarly to DOCP, the dose should be adjusted based on serum electrolyte concentrations. The dose may be increased in 0.05-
to 0.1-mg/day increments as needed based on serum electrolyte concentrations.3
Fludrocortisone has some glucocorticoid activity, but about 50% of dogs may need additional glucocorticoid supplementation.4 In some dogs, the amount of fludrocortisone that effectively maintains sodium and potassium concentrations may result in
clinical signs of glucocorticoid excess such as polyuria and polydipsia.1,3 In this situation, consider administering DOCP and an oral glucocorticoid such as prednisone. When changing from fludrocortisone
to DOCP, gradually taper the fludrocortisone over four to five days after DOCP is administered.1
CONCLUSION
Relative hypoadrenocorticism: An emerging concern
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Hypoadrenocorticism can be a frustrating disease since its presentation is often ambiguous. The disease can be life-threatening
if not rapidly recognized and treated and requires lifelong management. Nevertheless, with good client compliance, the prognosis
is favorable.2,13 Relative adrenal insufficiency, or RAI, is a condition that should be considered in any dog with sepsis and hypotension
that is refractory to volume resuscitation (see "Relative hypoadrenocorticism: An emerging concern"). With additional research, early recognition of dogs with RAI and administration of appropriate therapy may decrease mortality
in dogs with sepsis and possibly other forms of critical illness.
Christine A. Gaydos, DVM
Webster Groves Animal Hospital
8028 Big Bend Blvd.
Webster Groves, MO 63119
Amy DeClue, DVM, MS, DACVIM
Department of Veterinary Medicine and Surgery
College of Veterinary Medicine
University of Missouri
Columbia, MO 65211
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