Clinician’s Brief Subscriber Exclusive: Get 10% Off Standards of Care!
Clinician’s Brief subscribers get an exclusive discount on Standards of Care, the scenario-based clinical resource designed for real-world decision-making. Visit standards.vet and use code cb10off to save 10% on a Standards of Care subscription. (Valid until September 1, 2025.)
Sponsored by Standards of Care
Overview
Developed by our team of generalists and specialists, this excerpt represents just a sample of the guidance available in Standards of Care.
Hyperadrenocorticism (HAC), also known as hypercortisolemia or Cushing’s disease, is one of the most common endocrinopathies in dogs and is exceedingly rare in cats.
Most cases are caused by pituitary adenomas (ACTH-dependent disease), with fewer cases caused by adrenocortical tumors (ACTH-independent disease).
Although a clinical suspicion of HAC is fairly straightforward based on patient history, physical examination, and clinicopathologic findings, obtaining a definitive diagnosis may be challenging and commonly involves more than one diagnostic test.
Importantly, testing for HAC is not recommended in the absence of supportive clinical signs, regardless of clinicopathologic findings (eg, ALP elevation).
Several adrenal axis testing options are available, including screening and differentiating tests; however, test results must be interpreted relative to the clinical signs.
Treatment options differ based on the underlying etiology and consist of medical management, surgery, and radiation therapy.
Prognosis for clinical control is generally good, although complications like thromboembolic disease can occur and be life-threatening.
Expert Guidance to Diagnostic Scenarios
Because cases rarely follow the rules, Standards of Care monographs offer expert-driven, boots-on-the-ground clinical guidance for those complex, real-world scenarios that challenge even the best-laid protocols. Developed by the Standards of Care team of generalists and specialists, these targeted diagnostic scenarios spotlight the practical judgment calls and nuanced decisions general practitioners face every day.
Adrenal Axis Testing in Dogs With Known Comorbid Disease
Frequency of false-positive results on screening tests may increase with the severity of illness. Some dogs with nonadrenal illness have positive results on both low-dose dexamethasone suppression test (LDDST) and ACTH stimulation testing. Ideally, testing for HAC should be avoided if significant nonadrenal illness is present (ie, postponed until comorbid disease is resolved or controlled). In some situations (eg, diabetes mellitus), concurrent disease cannot be fully resolved. In these scenarios, adrenal axis testing should be performed once comorbid disease is stable.
Dogs Receiving Phenobarbital
The adverse effects of phenobarbital (and theoretically any drug metabolized by the cytochrome P450 system) can mimic HAC and include polyuria/polydipsia, polyphagia, and elevated ALP levels. A diagnosis of concurrent HAC in dogs receiving phenobarbital can be challenging, as a small percentage of dogs may not show suppression on LDDST. Available research has failed to demonstrate a significant effect of phenobarbital on adrenal axis testing. Current recommendations for patients receiving phenobarbital and showing clinical signs of HAC are to switch to another anticonvulsant and note whether clinical signs of HAC persist. If signs are persistent, adrenal axis testing is warranted.
These examples offer a glimpse into the type of diagnostic nuance offered in Standards of Care. Additional expert guidance on the following is available to subscribers:
Atypical or occult HAC
What if some of the dexamethasone or synthetic ACTH extravasates from the vein during testing?
Detection of bilateral adrenal tumors or nodules
Check out the full library at Standards of Care.
Unlock full access at standards.vet, and save 10% with code cb10off, exclusively for Clinician’s Brief subscribers. (Offer expires September 1, 2025.)
