Small Animal Dermatology, 3rd edition

402 DISEASES/DISORDERS

Must maintain daily (or BID) dosing for maintenance therapy, as opposed to

twice weekly for mitotane

Monitor sodium and potassium levels in treated dogs.

 L-deprenyl (selegiline hydrochloride):
Monamine oxidase inhibitor/dopamine agonist
May be used as an alternative treatment for PDH
Decreases pituitary ACTH secretion by increasing dopaminergic tone to the

hypothalamic-pituitary axis, decreasing serum cortisol concentrations

Indicated only for the treatment of uncomplicated PDH

Not recommended for treatment of PDH in dogs with concurrent illnesses such

as diabetes mellitus

Cannot be used to treat cortisol-secreting adrenocortical neoplasia

Medication effective in 20–30% of patients with pars intermedia disease

Initiate therapy with 1 mg/kg PO q24h and increase to 2 mg/kg PO q24h after 2

months if the response is inadequate

If this dose is also ineffective, discontinue and institute alternative therapy

Disadvantages include the need for life-long daily administration, the expense

of the medication, and the frequent lack of clinical response

Side effects are uncommon and include vomiting, diarrhea, and hyperactive

behavior

Do not use with other monoamine oxidase inibitors, tricyclic antidepressants,

serotonin reuptake inhibitors, amitraz, dobutamine, meperidine, linezolid, or

tramadol.

 Ketoconazole:
Inhibits mammalian steroidogenesis by blocking the cytochrome p450 enzyme

system, which is responsible for both androgen and cortisol production

Also inhibits ACTH secretion from pituitary corticotrophs

Dosage: 10 mg/kg PO BID initially; up to 20 mg/kg BID in some dogs

Indicated for dogs unable to tolerate mitotane or trilostane at doses necessary to

control HAC and preoperative control of HAC in dogs with ADH scheduled for

adrenalectomy

May be useful for palliation of clinical signs of HAC in dogs with AT

Over one-third of dogs reportedly fail to respond adequately to this drug

Adverse effects include anorexia, vomiting, diarrhea, lethargy, decreased

libido/reproductive hormones, and an idiosyncratic hepatopathy

Avoid concurrent use with ivermectin (increased ivermectin toxicity by

decreased clearance and enhanced penetration across the blood–brain barrier)

and antacids.

Alternative Therapies with Minimal or Unknown Effectiveness

Melatonin, flax seed oil with lignins, metyrapone, LC1699 (similar to metyrapone),

mifepristone, bromocriptine, cyproheptadine, cabergoline, aminoglutethimide, COR-

003 (enantiomer of ketoconazole), retinoic acid, gefitinib (EGFR antagonist).