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Today's VeTerinary PracTice | January/February 2016 | tvpjournal.com canine PiTuiTary dePendenT HyPeradrenocorTicism series Peer reviewed 36 Canine pituitary dependent hyperadrenocorticism (PDH), also known as Cushing's disease, is a common endocrine disorder in older dogs. This disorder is caused by a pituitary adenoma (PA) that secretes inappropriate amounts of adrenocorticotropic hormone (ACTH), which results in bilateral adrenal hyperplasia and disorderly and excessive production of cortisol by the adrenal gland. Read Part 1 of this series—Comparative Epidemiology & Etiology in Dogs & Humans (November/December 2015)—at tvpjournal.com. This article briefy described the diagnosis of PDH, including clinical signs, common laboratory fndings, and atypical presentations of canine PDH. BASELINE DIAGNOSTICS In all patients being screened for PDH, the following initial diagnostics should be performed prior to endocrine diagnostics: • Thorough history, including prior treatment with systemic or topical glucocorticoids • Physical examination (Table 1) • Complete routine database, including complete blood count, serum biochemical profile, urinalysis, urine culture, and blood pressure (Table 2). These diagnostics are important as the clinical signs of PDH are rarely pathognomonic, and patients are generally older and may have comorbidities that affect endocrine function tests (Table 3) and impact therapeutic options and prognosis. ENDOCRINE DIAGNOSTICS Specifc endocrine tests and imaging modalities are available to both diagnose PDH (Table 3) and distinguish between the various causes of hyperadrenocorticism (HAC). No single test is perfect and, if the initial screening test is negative and high clinical suspicion of PDH exists, additional tests should be performed to determine a defnitive diagnosis. Canine Pituitary DePenDent HyPeraDrenoCortiCism series Part 2: Diagnostic Approach David Bruyette, DVM, Diplomate ACVIM VCA West Los Angeles Animal Hospital, Los Angeles, California, and Veterinary Diagnostic Investigation and Consultation, Woodland Hills, California Table 1. Common Clinical Signs & Sequelae of PDH in Dogs • Polyuria and polydipsia • Polyphagia • Abdominal distension • Bilaterally symmetric endocrine alopecia • Panting • Hypertension • Urinary tract infections • Additional dermatologic signs: » Thin skin » Pyoderma » Calcinosis cutis Table 2. Common Laboratory Findings in Dogs with PDH HEMATOLOGIC ABNORMALITIES • "Stress" leukogram: » Neutrophilic leukocytosis » Lymphopenia » Eosinopenia • Mild thrombocytosis • Mild erythrocytosis SERUM BIOCHEMICAL ABNORMALITIES • Increased serum alkaline phosphatase • Milder increase in alanine aminotransferase • Hypercholesterolemia • Hypertriglyceridemia • Hyperglycemia URINALYSIS ABNORMALITIES • Decreased urine specifc gravity < 1.018 • Proteinuria • Urinary tract infection (even in absence of pyuria and bacteriuria) aCVIM Consensus Statement in 2012, the american College of Veterinary internal medicine (acvim.org) issued a consensus statement, Diagnosis of Spontaneous Canine Hyperadrenocorticism, that provides a thorough review of the diagnostic approach to patients with PDH and addresses many common clinical concerns. 1 access this statement at onlinelibrary.wiley .com/doi/10.1111/ jvim.12192/epdf.