The objective of this study was to report clinical and clinicopathological abnormalities in canine spontaneous hyperadrenocorticism (HAC) and assess the relationship between patient size and those findings. A questionnaire was made available to primary care veterinarians to gather information on cases diagnosed with canine spontaneous HAC. Inclusion criteria were an adrenocorticotropic stimulation test and/or low-dose dexamethasone suppression test consistent with HAC. Exclusion criteria included concurrent systemic diseases, any clinical sign (CS) not typically associated with HAC, a urinary corticoid:creatinine ratio within reference interval, administration of steroids during the 3 mo before diagnosis, treatment with any drug causing CSs of HAC, and ongoing treatment for canine spontaneous HAC. Sixty-two cases were identified. The prevalences of various CSs were similar to those historically reported. No association between the patient weight and CSs was identified. The platelet count was negatively correlated to the weight (P = .005, r2 = 0.3). Alanine aminotransferase (P = .016, r2 = 0.17) and alkaline phosphatase (P = .05, r2 = 0.0014) activities were positively correlated to the CS ratio. In this group of dogs, CSs were not significantly different between dogs ≤20 kg and dogs >20 kg. The prevalences of various clinical findings appeared to be similar to those historically reported. Dogs with more CSs tended to have higher alanine aminotransferase and alkaline phosphatase activities.