New York State Veterinary Conference at Cornell University
Dr. Peterson lectured to a packed room on Friday afternoon, and lectured for one hour on Saturday alongside Dr. Michael Broome.

On Sunday Dr. Peterson, along with four leading veterinary experts from around the country, served on a panel that discussed various controversial issues on the diagnosis and treatment of hyperthyroidism in a half-day Hyperthyroid Summit. The debate at the Summit was lively, with some heated discussion.

A great conference!

Getting ready for SEVC IN Barcelona
Dr. Peterson is excited to travel for the first time to Barcelona later this month for the Southern European Veterinary Conference (SEVC). Dr. Peterson will be presenting four lectures at the SEVC, a conference organized by the NAVC.

Results of a complete blood count, serum chemistry profile, and compete urinalysis were unremarkable with the exception of a slightly high serum alkaline phosphatase activity (835 IU/L; reference range, <100 IU/L) and a low urine specific gravity (1.008).

A urine culture was negative, ruling out a urinary tract infection. A serum T4 concentration was normal at 20 nmol/L (reference range, 10-55 nmol/L), excluding hypothyroidism.

Because the clinical signs and routine laboratory tests supported a diagnosis of hyperadrenocorticicism, an ACTH stimulation and low-dose dexamethasone suppression test were next performed. Results of the ACTH stimulation test revealed a slightly high basal cortisol (5 μg/dl; reference range, 1-4 μg/dl) with a slightly exaggerated response following ACTH injection (22 μg/dl; reference range, 7-18 μg/dl). Results of a low-dose dexamethasone suppression test showed a high-normal basal cortisol concentration (3.9 μg/dl) with inadequate cortisol suppression at both 4 hours (2.5 μg/dl; normal < 1.4 μg/dl) and 8 hours (2.5 μg/dl; normal < 1.4 μg/dl) post-dexamethasone (0.01 mg/kg, IV). The slightly exaggerated cortisol response to ACTH and lack of suppression following low-dose dexamethasone administration was considered diagnostic for hyperadrenocorticism.

To help determine the cause of the Cushing’s syndrome, an abdominal ultrasound examination was next performed. Ultrasonography revealed a large, hyperechoic liver, and enlargement of both adrenal glands (left adrenal width, 7.6 mm; right adrenal, 7.3 mm; normal < 7 mm). The bilateral adrenal enlargement excluded a cortisol-secreting adrenal tumor and was considered diagnostic for pituitary-dependent hyperadrenocorticism (PDH).

Treatment, Dose Adjustments, and Monitoring
Lulu was started on Vetoryl at the dosage of 30 mg once daily (3.0 mg/kg/day), given in the morning with food. On recheck at 14 days, history revealed that Lulu was more active and was drinking slightly less, but she still remained quite polyuric and polydipsic. Results of an ACTH stimulation test done 4-hours after the morning feeding and dosing showed a high basal cortisol value (5.0 μg/dl) with a post-ACTH cortisol value (9 μg/dl) that was higher-than-desired for Vetoryl treatment (post-ACTH cortisol < 5.5 μg/dl). The Vetoryl was continued at 30 mg once daily with a follow-up scheduled for 2 weeks later (at 30 days of treatment).

At 30 days, Lulu continued to show signs of polyuria and polydipsia and no hair regrowth was evident. Results of an ACTH stimulation test again showed high serum concentrations of basal cortisol (7.3 μg/dl) and post-ACTH cortisol (17.1 μg/dl). Because of Lulu’s persistent clinical signs and high cortisol values, the daily Vetoryl dosage was increased to 40 mg per day (4 mg/kg/day), each morning with food.

At 90-day recheck, Lulu was doing very well, with complete resolution of the polyuria, polydipsia, and lethargy. Early hair regrowth was evident.

Results of the CBC and serum chemistry panel were all within reference range limits. The ACTH stimulation test showed a basal cortisol value of 4.5 μg/dl, with a post-ACTH cortisol concentration of 5.3 μg/dl. This was considered good control of the Hyperadrenocorticism, so the Vetoryl was continued at the morning dosage of 40 mg with food.

At the 6-month recheck, Lulu was doing extremely well, with normal thirst and urination and good hair regrowth (Figure 2).

Results of the CBC, serum chemistry panel were normal. The ACTH stimulation test showed a basal cortisol of 1.3 μg/dl and a post-ACTH stimulated cortisol value of 1.9 μg/dl. Despite the fact that Lulu was doing so well, these serum cortisol concentrations were considered too low for Vetoryl treatment, and the dosage was decreased down to 20 mg once daily (2 mg/kg/day).