Female dogs are nonseasonally monoestrus, undergoing estrus at 5- to 12-month intervals. The luteal phase of the ovarian cycle in nonpregnant dogs is similar in duration and hormone profile to that of pregnant dogs, with high circulating concentrations of progesterone.1 Some dogs also secrete large amounts of GH from the mammary gland during diestrus in response to endogenous progesterone.2,3 Both progesterone and GH induce insulin resistance and may potentially cause diabetes mellitus in the luteal phase (ie, diestrus-associated diabetes mellitus).2,4,5 Marca and Loste6 studied circulating glucose and HbA1c concentrations in 11 Beagle bitches in the different phases of estrus; both glucose and HbA1c concentrations in plasma and whole blood, respectively, were slightly elevated during diestrus, compared with other stages of the estrual cycle. Our group has previously reported that some breeds, such as Swedish and Norwegian Elkhounds, are predisposed to onset of diabetes mellitus during diestrus.7,8 In addition to dogs with overt diabetes, there may be some Elkhounds with subclinical hyperglycemia during diestrus that have aberrations in their insulin response, without overt clinical signs of diabetes.
The purpose of the study reported here was to investigate whether circulating concentrations of glucose homeostasis biomarkers, progesterone, and growth hormone in healthy female Elkhounds differ during diestrus and anestrus and to compare those findings with data from dogs of other breeds. A secondary aim was to compare glucose homeostasis biomarker concentrations during diestrus and anestrus in dogs within each breed grouping.
Glycated hemoglobin A1c
Homeostasis model assessment
Homeostasis model assessment for beta-cell function
Homeostasis model assessment for insulin sensitivity
Insulin-like growth factor
Glucose, Thermo Clinical Labsystems Oy, Vantaa, Finland.
ABX Pentra Fructosamine, ABX Diagnostics, Montpellier, France.
Immulite 2000 Progesterone, Siemens Healthcare Diagnostics, Deerfield, Ill.
Canine C-peptide radioimmunoassay, Linco Research, St Charles, Mo.
Trasylol, Bayer, Göteborg, Sweden.
PGH-46HK, Linco Research, St Charles, Mo.
Haemaquant/Glycosal HbA1c system, provided by Bio-Rad, Hemel Hempstead, Hertfordshire, England.
STATA, version 11, SAS Institute Inc, Cary, NC.
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