The Treatment of Acute Adrenocortical Insufficiency in the Dog

Semiquantitative acid-base analysis in dogs with typical hypoadrenocorticism

OBJECTIVE

To describe the semiquantitative acid-base status of dogs with untreated naturally occurring typical hypoadrenocorticism and to compare this to the status determined by traditional acid-base analysis.

DESIGN

Retrospective study.

SETTING

University teaching hospital.

ANIMALS

Thirty-three dogs with newly diagnosed typical hypoadrenocorticism between 2000 and 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Dogs were included if they had newly diagnosed hypoadrenocorticism, post-ACTH stimulation serum cortisol concentration <2 μg/dL, and blood collected within 6 hours of presentation for acid-base, electrolyte, and serum biochemical assays. Dogs were excluded if the Na⁺ :K⁺ ratio was ≥28 or the dog had received a mineralocorticoid-containing corticosteroid medication within the preceding month. Traditional acid-base analysis identified normal acid-base status in 1 dog, simple respiratory acid-base abnormalities in 2 of 33 dogs, and simple metabolic acidosis in 14 of 33 dogs. A mixed disorder was most common, noted in 16 of 33 dogs. The semiquantitative approach identified metabolic abnormalities in all cases. All dogs had ≥1 acidifying process, and 29 of 33 had both acidifying and alkalinizing processes. Acidosis attributable to excess free water was present in all dogs, and an acidifying phosphate effect was present in 27 of 33. Hyperlactatemia contributed to the acidosis in 8 of 33 dogs, with a median (range) lactate concentration of 1.5 mmol/L (13.5 mg/dL) (0.3-4.2 mmol/L [2.7-37.8 mg/dL]).

CONCLUSIONS

Dogs with untreated Addison's disease have complex acid-base derangements. The semiquantitative approach to acid-base analysis provides greater insight into the underlying mechanisms of metabolic acid-base abnormalities in these dogs, particularly because lactic acidosis appears to be a minor influence in most cases.

Presumptive iatrogenic hypoadrenocorticism induced by high-dose ketoconazole administration in a dog

A 11‐year‐old male neutered Shih Tzu was referred to a tertiary facility with a history of weight loss, decreased appetite, polydipsia, and lethargy. The dog had a 10‐year history of nonspecific allergic dermatitis and was being treated with 16 mg/kg of ketoconazole q12h for Malassezia dermatitis. Vague gastrointestinal signs, hypocholesterolemia, and lack of a stress leukogram increased suspicion for hypoadrenocorticism (HA). An adrenocorticotropic hormone (ACTH) stimulation test identified hypocortisolemia on pre‐ and post‐ACTH samples and ketoconazole was discontinued. After a short course of corticosteroid treatment, an ACTH stimulation test was repeated and pre‐ACTH cortisol concentration was within the reference range, and the post‐ACTH cortisol concentration was mildly increased. The temporal association between return of adequate adrenocortical cortisol production and discontinuation of ketoconazole led to the conclusion that the dog had developed iatrogenic HA secondary to ketoconazole treatment.

Desoxycorticosterone Pivalate Duration of Action and Individualized Dosing Intervals in Dogs with Primary Hypoadrenocorticism

Background

Clinicians alter dosing for desoxycorticosterone pivalate (DOCP) to mitigate costs, but this practice has not been critically evaluated in a prospective clinical trial.

Hypothesis/Objectives

The duration of action of DOCP is longer than 30 days in dogs with primary hypoadrenocorticism (PH).

Animals

A total of 53 client‐owned dogs with PH. Twenty‐four dogs with newly diagnosed PH (Group 1) and 29 dogs with treated PH (Group 2).

Methods

Prospective, multicenter, clinical trial. For phase I, DOCP was administered and plasma sodium and potassium concentrations were measured until the dog developed hyponatremia or hyperkalemia at a planned evaluation, or displayed clinical signs with plasma electrolyte concentrations outside of the reference interval independent of a planned evaluation, thus defining DOCP duration of action. Plasma electrolyte concentrations then were assessed at the end of the individualized dosing interval (IDI; i.e., DOCP duration of action minus 7 days, phase II and at least 3 months after concluding phase II, phase III).

Results

The duration of action of DOCP in dogs in phase I with naïve PH (n = 24) ranged from 32 to 94 days (median, 62 days; 95% confidence interval [CI], 57, 65) and previously treated PH (n = 29) from 41 to 124 days (median, 67 days; CI, 56, 72). Overall, the final DOCP dosing interval for all dogs that completed phase II (n = 36) ranged from 38 days to 90 days (median, 58 days; CI, 53, 61). No dog that completed phase III (n = 15) required reduction in the IDI. The DOCP duration of action, independent of group, was not significantly associated with several baseline variables. The median drug cost reduction using IDI was approximately 57.5% per year.

Conclusion and Clinical Importance

The duration of action of DOCP in dogs with PH is >30 days, and plasma sodium and potassium concentrations can be maintained with an IDI >30 days long term.

Treatment of Acute Adrenal Insufficiency

Hypoadrenocorticism is caused by a lack of endogenous glucocorticoid and mineralocorticoid. These deficiencies can cause a myriad of clinical signs. This disease is uncommon and its clinical presentation is similar to many much more commonly recognized diseases such as renal failure and various gastrointestinal disorders. Severely affected patients may present in a life-threatening adrenocortical crisis, which is characterized by variable degrees of volume depletion and electrolyte abnormalities. The emergency clinician should maintain a high clinical suspicion for hypoadrenocorticism, as early recognition and rapid treatment of hypovolemia and electrolyte abnormalities can be lifesaving. The approach to emergency treatment of hypoadrenocorticism should be to recognize and treat life-threatening arrhythmias, replace intravascular volume and normalize perfusion, correct electrolyte abnormalities and hypoglycemia, administer glucocorticoids, and perform the adrenocorticotrophic hormone stimulation test for definitive diagnosis. Patients with this condition should have a favorable outcome when treated appropriately.