Iatrogenic adrenal atrophy following oral corticotherapy is not reliably identified ultrasonographically in cats.

Background: In dogs, corticosteroid administration is known to decrease adrenal gland height when measured ultrasonographically. However, comparable information is lacking in cats.

Objectives: i) Validate that the adrenal height of our control population without corticosteroid administration was similar to previous data, ii) determine effects of dose and duration of oral corticosteroid therapy on adrenal height, and iii) determine an adrenal size threshold to differentiate cats receiving corticosteroids or not.

Animals And Procedures: Adult cats (N = 308) that received abdominal ultrasonographic examination(s) were retrospectively recruited and allocated into 2 groups: those with and without oral corticosteroid use. Cats receiving corticosteroids were subdivided into 6 subgroups by dose (supraphysiologic, anti-inflammatory, or immunosuppressive) and duration of therapy (≤ 1 mo or > 1 mo).

Results: Adrenal height in cats without corticosteroid therapy was comparable to previous studies. An anti-inflammatory corticosteroid dose for > 1 mo caused a 21.4% decrease in adrenal height (mean difference of 0.8 mm; = 0.009). However, no difference in adrenal height was noted in the other subgroups ( > 0.21), and no useful adrenal height threshold was established.

Conclusion And Clinical Relevance: Feline iatrogenic adrenal atrophy may be difficult to establish with ultrasonography, as only cats receiving anti-inflammatory corticosteroid doses for > 1 mo had a modest (< 1 mm) decrease in adrenal height.