Evaluation of the Efficacy of Trilostane in the Treatment of Canine Hyperadrenocorticism: Retrospective Analysis of 17 Cases
World Small Animal Veterinary Association World Congress Proceedings, 2009
A.M. Vargas1; A.L.S. Santos2; V.U. Fonseca2
1ENDOCRINOVET, São Paulo, Brazil; 2School of Veterinary Medicine and Animal Science, São Paulo University, São Paulo, Brazil

Spontaneous hyperadrenocorticism (HAC) or Cushing´s syndrome, caused by excessive production of steroid hormones from the adrenal cortex, is one of the most common endocrinopathies present in midage to older dogs. Its main clinical symptoms are polyuria, polydipsia, polyphagia, loss of fur or poor coat condition, and abdominal enlargement, while the most common laboratory alterations are a "stress leukogram", increased serum alkaline phosphatase and cholesterol levels, and low urinary density (below 1.015). Diagnosis is based on clinical history, laboratory analysis (hemogram, serum biochemical analysis, urinalysis, urine culture, and antibiogram), abdominal ultrasonography, and ACTH stimulation test or dexamethasone suppression test. Preliminary studies suggest that trilostane is efficient in controlling the clinical signs of canine HAC during prolonged periods of time. Trilostane is a competitive inhibitor of 3β-hydroxysteroid dehydrogenase, and thus, inhibits production of cortisol by the adrenal cortex. Initial dosage is recommended at 2 to 10 mg/kg per day. In this study, we evaluated 17 dogs diagnosed with HAC and treated with trilostane (2 mixed-breeds, 2 Brazilian Terriers, 3 Yorkshires, and 10 Poodles), of which 6 were males and 11 females, all aged between 7 and 12 years (10.0 ± 1.9). In total, 2 dogs (11.7%) interrupted treatment due to the development of complications or to non-remission of clinical symptoms, while the 15 other dogs (88.3%) were evaluated after 6 months of treatment. The mean daily dose in these was 6.2 ± 2.2 mg/kg/day. According to the clinical evaluation and as related by anamnesis, pathognomonic symptoms of HAC were resolved. Laboratory analysis demonstrated a reduction in serum alkaline phosphatase, alanine aminotransferase, cholesterol, and triglyceride levels. In the ACTH stimulation test, mean cortisol levels after 1 hour of stimulation was 4.8 ± 2.55 μg/dL, which is close to values recommended for treated animals (1 to 5 μg/dL). When compared to their reference values, the sodium: potassium ratio was decreased, but no clinical alterations due to this were found. On the other hand, patients did not present increased blood urea, a common adverse effect described in literature. The use of trilostane in the management of canine hyperadrenocorticism is a safe and efficient therapeutic choice.

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A.M. Vargas
São Paulo, Brazil

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