Diagnosis of naturally-occurring Cushing's syndrome by primary care veterinarians in selected European countries

Background: Several tests are available to diagnose naturally-occurring Cushing's syndrome in dogs but there is a paucity of information on how primary care veterinarians (PCVs) use or interpret them. Objectives: Determine how PCVs from selected European countries diagnose Cushing's syndrome in dogs. Methods: Cross-sectional survey study assessing testing protocols used by PCVs for screening and differentiation of Cushing's syndrome. Results: Two thousand one hundred and seventy-eight responses from 9 European countries were included. When Cushing's syndrome was suspected, 98.7% of respondents perform endocrine testing, whereas 1.2% rely on a treatment trial. Among the former, 59.9% reported performing screening tests in the absence of supportive clinical signs but with consistent clinicopathological abnormalities. Of 2150 respondents who performed endocrine testing, 66.6% report always using the same initial screening tests regardless of their pretest suspicion of disease. The tests most reported are the ACTH stimulation test (34.8%), low-dose dexamethasone suppression test (LDDST; 30.4%) or a combination of different tests (25.2%). In the absence of financial constraint, 1419 (66.0%) respondents always attempted differentiation, using abdominal ultrasonography (81.0%) and LDDST (46.1%). Overall, 69.8% of respondents reported offering referral to a specialist in ≤20% of cases suspected or diagnosed with Cushing's syndrome over the previous 5 years. Conclusions and Clinical Importance: Testing protocols vary among PCVs. Almost 60% of respondents potentially screen dogs without consistent clinical signs, raising concerns for overdiagnosis. A proportion never attempt differentiation, which likely affects prognosis. Cases are rarely referred to a specialist, reflecting that Cushing's syndrome is mainly managed in primary care practices. These results suggest that there is room for further education of PCVs.