Support by FAPESP (Process # 03/14127-0).

Diabetic ketoacidosis (DKA) is a common complication of diabetes mellitus in dogs, carrying a high mortality. Since proper correction of the alterations in acid-base composition is an important part of the adequate management of DKA, the knowledge of these derangements is essential. The objective of this study was to describe the acid-base disturbances of dogs with DKA and further characterize them, according to their frequency, adequacy of the secondary physiologic response, and occurrence of mixed disturbances. Sixty dogs with DKA were enrolled in the study. Arterial blood pH and gas tensions, plasma electrolytes, serum beta-hydroxybutyrate (beta-OHB), glucose, albumin and urea concentrations were determined for all dogs included. Dogs were evaluated individually and systematically by the traditional approach to the diagnosis of acid-base disorders. Most of the dogs had a high anion gap acidosis, with appropriated respiratory response (n = 18; 30%) or concurrent respiratory alkalosis (n = 14; 23%). Hyperchloremic acidosis with moderated to marked increases in beta-OHB was observed in 18 dogs (30%) and 7 of these patients had concurrent respiratory alkalosis. Hyperchloremic acidosis with mild increase in beta-OHB was observed in 6 dogs (10%). Four dogs (7%) had a high anion gap acidosis with mild increase in beta-OHB and respiratory alkalosis. Patients with concurrent respiratory alkalosis had lower plasma potassium concentrations. Dogs with hyperchloremic acidosis had milder increases in beta-OHB and acidosis, and better preserved renal function, based on serum urea concentrations. We concluded that, on average, dogs with DKA had a high anion gap acidosis, but mixed acid-base disorders were common, chiefly high anion gap acidosis and concurrent respiratory alkalosis, and hyperchloremic acidosis with moderated to marked increases in serum beta-OHB.