Case file: BOCA, an 8-year-old spayed female Shih Tzu weighing 14 lb (6.4 kg)
Patient history and initial diagnostic workup
Boca was presented to Parkview Veterinary Hospital for evaluation of polyuria, polydipsia, skin lesions, and signs of gastrointestinal
discomfort. Boca had a previous history of intermittent gastrointestinal signs including stool that would vary from soft to
liquid, inappropriate fecal elimination in the house, and vomiting. These signs had previously improved after her diet was
changed to a food containing hydrolyzed protein.
Cynthia Nichols, DVM
Physical examination revealed pain upon abdominal palpation, borborygmi, and calcinosis cutis on the dorsal head and neck.
A serum chemistry profile showed elevated alkaline phosphatase (ALP), alanine aminotransferase (ALT), and gamma glutamyl transferase
(GGT) activities. Boca's urine specific gravity was 1.014.
An abdominal ultrasonographic examination revealed a biliary mucocele and hepatomegaly. Bocca was subsequently referred to
a veterinary surgeon, and her gallbladder was removed.
Adrenal function test results
An ACTH stimulation test performed two weeks after the gallbladder surgery showed a baseline cortisol concentration of 8.1
µg/dl (reference range = 1.0 to 5.0 µg/dl) and a one-hour post-ACTH cortisol concentration of 44.5 µg/dl (reference range
= 8.0 to 17.0 µg/dl). These results were consistent with a diagnosis of hyperadrenocorticism.
Boca, after treatment with VETORYL® Capsules (trilostane) and awaiting re-examination.
I discussed two medical treatment options with the owners—mitotane and VETORYL® Capsules (trilostane). I advised the owners
that mitotane was not approved for use in dogs and that I had experience with using mitotane to treat canine hyperadrenocorticism
but not with VETORYL Capsules. The owners elected to treat Boca with mitotane in an extra-label fashion.
After 11 days of once daily treatment with an induction dose of mitotane, Boca's baseline cortisol concentration was 1.0 µg/dl
and her one-hour post-ACTH cortisol concentration was 1.1 µg/dl. Based on these results, the induction dose of mitotane was
discontinued and a twice-weekly maintenance dose of mitotane was started. A low dose of prednisone was also given on the mitotane
After one month on the maintenance dose of mitotane with prednisone, Boca's owners reported that she had diarrhea and lethargy
on the days she received mitotane. Boca's baseline cortisol concentration was 2.8 µg/dl and her one-hour post-ACTH cortisol
concentration was 5.2 µg/dl. Her ALP, ALT, and GGT activities were still elevated. Boca's diarrhea was managed with supportive
care and the prednisone and mitotane were continued at the same dosages.
After one year of treatment with mitotane and prednisone, Boca presented for evaluation of vomiting and diarrhea with tenesmus.
Her ALP, ALT, and GGT activities were still elevated. An ACTH stimulation test showed a baseline cortisol concentration of
6.8 µg/dl and a one-hour post-ACTH cortisol concentration of 24.5 µg/dl.
Because Boca would again need to receive mitotane at an induction dose and she had not tolerated mitotane well to date, I
recommended discontinuing treatment with mitotane and prednisone and starting treatment with VETORYL® Capsules (trilostane)
one month later.