Clinicopathologic and electrocardiographic features of Akita dogs with high and low erythrocyte potassium phenotypes

Effects of handling and storage on potassium concentration in plasma and serum samples obtained from cats

OBJECTIVE

To compare potassium concentrations in feline plasma and serum samples analyzed promptly after collection or after 20 to 28 hours of refrigerated storage.

ANIMALS

41 cats.

PROCEDURES

A venous blood sample was obtained from each cat. Aliquots were placed in 2 tubes without anticoagulant (blood was allowed to clot to derive serum) and 2 tubes with heparin (to derive plasma). One serum and 1 plasma sample were kept at room temperature and analyzed within 60 minutes after collection (baseline); the other serum and plasma samples were analyzed after 20 to 28 hours of refrigerated storage. At both time points, serum and plasma potassium concentrations were measured.

RESULTS

Median baseline serum potassium concentration (4.3 mmol/L) was significantly higher than median baseline plasma potassium concentration (4.1 mmol/L). The median difference between those values was 0.4 mmol/L (95% CI, 0.2 to 0.5 mmol/L). Compared with their respective baseline measurements, the median serum plasma concentration (4.8 mmol/L) and median plasma potassium concentration (4.6 mmol/L) were higher after 20 to 28 hours of refrigeration.

CLINICAL RELEVANCE

Results indicated that with regard to potassium concentration in feline blood samples, clotting or refrigerated storage for 20 to 28 hours results in a significant artifactual increase. Detection of an unexpectedly high potassium concentration in a cat may represent pseudohyperkalemia, especially if the blood sample was placed in a no-additive tube, was stored for 20 to 28 hours prior to analysis, or both.

Evaluation of frequency and intensity of asymptomatic anisocytosis in the Japanese dog breeds Shiba, Akita, and Hokkaido

Microcytosis is observed in healthy Japanese breed dogs. The aim of the study was to evaluate the frequency and intensity of asymptomatic anisocytosis using a three-grade scale in Japanese dog breeds with special emphasis on the following indices: mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, and red blood cell distribution width. The retrospective study included analyses of blood morphology and blood smear for clinically healthy Japanese dog breeds Shiba, Akita, and Hokkaido aged from 6 months to 14 years, performed as a part of preventative care. A total of 74 dogs of both sexes were qualified for the study. The group included both neutered and non-neutered animals (Akita – 17 females, 12 males, Shiba – 24 females, 18 males, Hokkaido – 2 females, 1 male). The blood smear revealed significant anisocytosis in 60.8% and mild anisocytosis in 28.4% of the tested dogs – 89.2% in total. Microcytosis was reported for 25.7% of the tested Japanese breed dogs. Reduced mean cell haemoglobin and mean cell haemoglobin concentration were diagnosed in 75.7% and 40.5% of dogs, respectively. Red blood cell distribution width as an anisocytosis indicator exceeded the norm in 12% of the tested dogs. Compared to mixed breed dogs, the Japanese breeds had a reduced mean cell volume, mean cell haemoglobin concentration and significant anisocytosis in the blood smear as well as a higher red blood cell distribution width indicator. Veterinarians should consider these differences when interpreting the results of morphological blood tests.

Akita dogs possess GLUT1 in erythrocytes, and Na,K-ATPase activity enables more efficient ascorbic acid recycling

We investigated hematologic characteristics of healthy Akita dogs. All were found to contain glucose transporters, GLUT1 and GLUT4, in erythrocyte membrane, whereas Beagle and any other Western dogs have only GLUT4. Of 47 Akitas, ten showed high K and low Na concentrations with elevated glutathione (GSH) in erythrocytes due to Na,K-ATPase activity in the membrane (HK). Akitas showed increased capacity for recycling vitamin C or ascorbic acid (AA) from oxidized ascorbic acid (DHA) compared to Beagle dogs. Particularly, HK Akitas performed even greater AA recycling and ferricyanide reduction than normal Akitas which have normal GSH, low K and high Na concentrations (LK). All HK Akitas also had stomatin in erythrocyte membrane, while half of LK Akitas had it at lower levels than HK Akitas. Stomatin did not have any influence on AA recycling. GLUT1, Na,K-ATPase and stomatin in erythrocytes are characteristics of Akita dogs, and the high prevalence of these proteins suggests their positive roles in biological efficiency.