Treatment of hyperadrenocorticism in a guinea pig (Cavia porcellus)

Abstract Background Hyperadrenocorticism is an uncommon guinea pig disease, but it is an important rule out for bilateral symmetrical non-pruritic alopecia, polyuria, polydipsia, and other generalized signs of illness. Diagnostic testing options are limited due to lack of reference intervals. Testing is challenging due to daily fluctuations in cortisol, stress, concurrent disease, obtaining sufficient samples, and large/variable adrenal gland size in normal guinea pigs. Case description A three-and-a-half-year-old female guinea pig (Cavia porcellus) presented for a five-week history of bilateral symmetrical alopecia, polyuria, and polydipsia. Abdominal ultrasound revealed small adrenal glands bilaterally. An ACTH stimulation test revealed markedly elevated cortisol pre- and post-stimulation. Treatment with trilostane was initiated (2-4 mg/kg PO q12h), which resolved the clinical signs after three months with no adverse effects noted. The guinea pig later became refractory to treatment and had lost significant weight, at which time an ultrasound was performed and revealed a right adrenal gland mass. Conclusions Diagnosing hyperadrenocorticism in guinea pigs is challenging and cases can present similarly to ovarian cysts. Diagnosis can be achieved using a combination of clinical signs, abdominal ultrasound, cortisol testing, and ACTH stimulation testing. Case relevance This report highlights the need for establishment of reference intervals for traditional screening and differentiating tests, as well as reporting effective therapeutic protocols.