Formulae to correct sodium concentrations for serum water fraction in cases of hypo- and hyperproteinemia in cats.

BACKGROUND: Biochemistry analyzers in many high-throughput laboratories use indirect potentiometry to determine serum electrolyte concentrations, which involves a pre-analytical dilution step that may be associated with artifactual increases or decreases in electrolyte concentrations under circumstances of altered serum water fraction (SWF). Severe hypo- and hyperproteinemia, conditions that cause altered SWF, are recognized but under-emphasized causes of falsely measured serum sodium concentrations. OBJECTIVES: The goals of this study were to determine the average actual SWF (SWFA ) and establish formulae to correct serum sodium concentration measured by indirect potentiometry in hypo- and hyperproteinemic cats. METHODS: Serum samples from 112 feline patients were analyzed for electrolytes (measured by both indirect and direct potentiometry), total protein, albumin, triglycerides, and cholesterol. Each serum sample was also lyophilized to determine the SWFA . A feline-specific formula to estimate SWF (SWFE-FEL ) was developed and evaluated with a multivariable linear model. RESULTS: The mean SWFA in this population of cats was 91.2%, which was significantly different (P < .0001) than the mean (93.9%) calculated using the human estimated formula (SWFE-HUM ). The formula devised for the SWFE-FEL better recapitulated the SWFA than did the SWFE-HUM , and the corrected sodium concentrations calculated using the feline formula were better correlated with serum sodium measured by direct potentiometry than those determined using the human formula. CONCLUSIONS: Application of feline-specific formulae is expected to limit the misinterpretation of electrolyte data from indirect potentiometry when altered SWF occurs. To demonstrate this, a case example of a hypoproteinemic cat is provided.

Clinically healthy overweight and obese dogs differ from lean controls in select CBC and serum biochemistry values.

BACKGROUND: Obesity is a global disease, affecting nearly half a billion people. Unfortunately, this trend is mirrored in our canine population. OBJECTIVES: As obesity is a complex inflammatory disease, there is a need to determine whether routine medical screening tests may indicate, or be influenced by, its presence. The objective of the current study was to determine if significant differences exist between CBC and biochemical profile values from control vs overweight/obese, client-owned dogs considered clinically healthy. METHODS: Dogs presented for routine health examinations, including minor dental or elective surgical procedures, were retrospectively identified from a hospital population. Animals were allocated to 2 categories based on body condition score (BCS), and data were analyzed by Mann-Whitney nonparametric analysis with statistical significance at a P ≤ .05. RESULTS: After exclusions, 116 dogs were assigned to the overweight/obese group (BCS ≥ 7) and 240 dogs to the control group (BCS = 4-6). Overweight/obese dogs had higher total leukocyte counts and higher plasma protein and globulin concentrations. Other differences were attributed to decreased serum water fraction (increased sodium, albumin, calcium, and anion gap) in the overweight/obese group. Interestingly, chloride concentration was decreased (in the face of increased sodium) in the obese group. CONCLUSIONS: There is CBC and biochemical evidence to support the concern that obesity influences laboratory values, even in dogs considered clinically healthy. Prospective studies aimed at characterizing these changes are needed to provide insight into the connection between obesity and its comorbidities.

Hematology and biochemistry of aging-evidence of "anemia of the elderly" in old dogs.

BACKGROUND: Effects of aging on hematologic and biochemical variables are well described in people. Anemia of the elderly is attributed to iron deficiency, anemia of chronic disease, chronic kidney disease, myelodysplasia, or idiopathic causes. Limited studies have examined these variables in aging dogs, but they have typically examined single breeds in research settings. OBJECTIVE: The objective of this study was to identify differences in CBC and biochemistry values between adult and aged dogs of many breeds. METHODS: Dogs presenting for wellness examinations and minor dental/elective surgeries that were otherwise clinically healthy were retrospectively identified. Dogs were categorized by age: adult (1-7.9 years), senior (8-11.9 years), and geriatric (12+ years). Standard CBC and biochemistry data were collated. Asian breeds, Greyhounds, and dogs with data indicating overt underlying disease were excluded. The Kruskal-Wallis test was used to compare groups with statistical significance set at P ≤ .05. RESULTS: Hematocrit, MCV, and serum iron decreased with age, indicating possible iron-restricted erythropoiesis (IRE), due to iron deficiency or low-grade chronic inflammation. Total proteins, globulins, and platelet counts increased with age while albumin decreased, suggesting low-grade inflammation. Urea was increased in older dogs without a concurrent increase in creatinine, which points toward gastrointestinal bleeding or dehydration. CONCLUSION: Clinically healthy, aging dogs have changes in laboratory variables that indicate altered physiologies compared to younger adult animals, including evidence of IRE, inflammation, and potential gastrointestinal bleeding, suggesting a similar trend to that of elderly human beings. Future studies will examine markers of iron metabolism and inflammation in aging dogs.