Objective—To determine vasopressin (VP) secretory
capacity during osmotic stimulation and the response
to desmopressin treatment in dogs with pyometra
and control dogs.
Animals—6 dogs with pyometra before and after
ovariohysterectomy and 6 control dogs.
Procedure—Urine osmolality (Uosm) was measured
during 12 hours. Values measured on the first day
defined the basal Uosm pattern. On the second day,
dogs were given desmopressin to induce a desmopressin-stimulated Uosm pattern. On day 3, the VP
response to osmotic stimulation was examined.
Results—Median Uosm on day 1 was 340 mOsm/kg
(range, 104 to 1,273 mOsm/kg) and 807 mOsm/kg
(range, 362 to 1,688 mOsm/kg) in dogs with pyometra
before and after surgery, respectively, and 1,511
mOsm/kg (range, 830 to 1,674 mOsm/kg) in control
dogs. Median Uosm during desmopressin treatment
was 431 mOsm/kg (range, 168 to 1,491 mOsm/kg)
and 1,051 mOsm/kg (range, 489 to 1,051 mOsm/kg) in
dogs with pyometra before and after surgery, respectively,
and 1,563 mOsm/kg (range, 1,390 to 2,351) in
control dogs. In dogs with pyometra, threshold for VP
secretion was lower before surgery (median, 340
mOsm/kg; range, 331 to 366 mOsm/kg) than after
surgery (median, 358 mOsm/kg; range, 343 to 439
mOsm/kg) or in control dogs (median, 347 mOsm/kg;
range, 334 to 360 mOsm/kg). Highest maximum plasma
VP values were found in dogs with pyometra.
Conclusions and Clinical Relevance—Dogs with
pyometra had increased urine concentration in
response to desmopressin but not to the degree of
control dogs, whereas VP secretory ability was not
reduced. (Am J Vet Res 2004;65:404–408)
Objective—To evaluate plasma concentrations of growth hormone (GH) and insulin-like growth factor I (IGF-I) in healthy dogs and large-breed dogs with dilated cardiomyopathy (DCM).
Animals—8 dogs with DCM and 8 healthy control dogs of comparable age and body weight.
Procedures—Blood samples for determination of the pulsatile plasma GH profile were collected from all dogs at 10-minute intervals between 8:00 am and 8:00 pm. Plasma IGF-I concentration was determined in the blood sample collected at 8:00 am.
Results—No significant differences in plasma IGF-I concentrations, basal plasma GH concentration, GH pulse frequency, area under the curve above the zero line and above the baseline for GH, and GH pulse amplitude were found between dogs with DCM and control dogs.
Conclusions and Clinical Relevance—Results did not provide evidence for an association between DCM in dogs and a reduction in plasma concentrations of GH or IGF-I. Therefore, reported positive effects of GH administration are most likely attributable to local effects in the heart.
Objective—To investigate the physiologic endocrine effects of food intake and food withholding via measurement of the circulating concentrations of acylated ghrelin, growth hormone (GH), insulin–like growth factor-I (IGF-I), glucose, and insulin when food was administered at the usual time, after 1 day's withholding, after 3 days' withholding and after refeeding the next day in healthy Beagles.
Animals—9 healthy Beagles.
Procedures—Blood samples were collected from 8:30 AM to 5 PM from Beagles when food was administered as usual at 10 AM, after 1 day's withholding, after 3 days' withholding, and after refeeding at 10 AM the next day.
Results—Overall mean plasma ghrelin concentrations were significantly lower when food was administered than after food withholding. Overall mean plasma GH and IGF-I concentrations did not differ significantly among the 4 periods. Circulating overall mean glucose and insulin concentrations were significantly higher after refeeding, compared with the 3 other periods.
Conclusions and Clinical Relevance—In dogs, food withholding and food intake were associated with higher and lower circulating ghrelin concentrations, respectively, suggesting that, in dogs, ghrelin participates in the control of feeding behavior and energy homeostasis. Changes in plasma ghrelin concentrations were not associated with similar changes in plasma GH concentrations, whereas insulin and glucose concentrations appeared to change reciprocally with the ghrelin concentrations.