Updates on hypoadrenocorticism - Veterinary Medicine
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Updates on hypoadrenocorticism
The lack of a stress leukogram in dogs with gastrointestinal signs may signal this potentially life-threatening disease. This review will help ensure that you aren't overlooking other clinical signs and that you know the latest about diagnosing and treating canine hypoadrenocorticism.


VETERINARY MEDICINE


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*
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*
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
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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Source: VETERINARY MEDICINE,
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