Plasma progesterone concentrations in dairy cows with cystic ovaries and clinical responses following treatment with fenprostalene

Sixty-two dairy cows diagnosed as having cystic ovarian degeneration were used to study the correlation between rectal palpation findings and plasma progesterone concentrations and the response of cysts to treatment using fenprostalene, a luteolytic agent. Rectal palpation accurately determined the presence of luteal cysts as confirmed by plasma progesterone concentrations of 3 ng/mL or more. Treatment with fenprostalene was very effective for luteal cysts: a high percentage of treated cows exhibited estrus within seven days after treatment. The conception rate following artifical insemination during the induced estrus was 87.5% (21/24). Rectal palpation was much less accurate for the diagnosis of follicular cysts. Cows diagnosed as having follicular cysts had wide variations in plasma progesterone concentrations. Response to fenprostalene treatment was poor in cows with nonluteinized cystic follicles associated with low progesterone concentrations. However, cows diagnosed as having follicular cysts, but with progesterone concentrations of 1 ng/mL or more, responded better to fenprostalene treatment than cows with low progesterone concentrations.

It was concluded that, if correctly diagnosed, luteal cysts can be successfully treated with fenprostalene, and conception rates following treatment can be expected to be normal.

     

Plasma cortisol and progesterone responses to low doses of adrenocorticotropic hormone in ovariectmized lactating cows

The objective of this study was to describe the responses of the plasma progesterone and cortisol concentrations in ovariectomized lactating cows to low doses of adrenocorticotropic hormone (ACTH). The estrous cycles in 3 lactating cows were synchronized, and the cows were ovariectomized in the luteal phase. ACTH challenge tests were conducted at doses of 3, 6, 12 and 25 IU. Blood samples were collected at 30 min intervals, and the plasma progesterone and cortisol concentrations were analyzed by EIA. A concomitant rise in plasma progesterone and plasma cortisol was observed in cows treated with 12 IU or higher doses of ACTH. Significant increments in the plasma cortisol concentrations were observed at all doses of ACTH. The means (+/- SE) of the peak plasma progesterone concentrations after the 3, 6, 12 and 25 IU ACTH challenge tests were 0.6 +/- 0.1, 1.3 +/- 0.4, 1.5 +/- 0.3 and 2.4 +/- 0.3 ng/ml, respectively. The means of the peak plasma cortisol concentrations in the 3 cows after the ACTH challenge were 14.0 +/- 1.5, 17.0 +/- 2.5, 23.3 +/- 3.0, and 33.3 +/- 7.0 ng/ml, respectively. The effects of the doses, time after treatment, and their interaction on the plasma progesterone concentrations after the ACTH challenge were significant (P<0.01). Likewise, the effects of the doses, time after treatment, and their interaction on the plasma cortisol concentrations after the ACTH challenge were significant (P<0.01). The mean AUC values for the plasma progesterone and cortisol concentrations after the ACTH treatments were also significantly affected by the dose of ACTH (P<0.01 and P<0.05, respectively). A significantly positive correlation was obtained between the peak plasma progesterone and cortisol concentrations after different doses of ACTH (r=0.7, P<0.05). The results suggest that lactating dairy cows are capable of secreting a significant amount of adrenal progesterone, reaching up to the minimal concentration necessary to cause suppression of estrus in response to 12 IU ACTH (P<0.01). The concomitant plasma cortisol concentration was 23.3 ng/ml.     

Plasma calcium, inorganic phosphate and magnesium during hypocalcaemia induced by a standardized EDTA infusion in cows

The intravenous Na2EDTA infusion technique allows effective specific chelation of circulating Ca2+ leading to a progressive hypocalcaemia. Methods previously used were not described in detail and results obtained by monitoring total and free ionic calcium were not comparable due to differences in sampling and analysis. This paper describes a standardized EDTA infusion technique that allowed comparison of the response of calcium, phosphorus and magnesium between 2 groups of experimental cows. The concentration of the Na2EDTA solution was 0.134 mol/l and the flow rate was standardized at 1.2 ml/kg per hour. Involuntary recumbency occurred when ionised calcium dropped to 0.39-0.52 mmol/l due to chelation. An initial fast drop of ionized calcium was observed during the first 20 min of infusion followed by a fluctuation leading to a further drop until recumbency. Pre-infusion [Ca2+] between tests does not correlate with the amount of EDTA required to induce involuntary recumbence. Total calcium concentration measured by atomic absorption remained almost constant during the first 100 min of infusion but declined gradually when the infusion was prolonged. The concentration of inorganic phosphate declined gradually in a fluctuating manner until recumbency. Magnesium concentration remained constant during infusion. Such electrolyte responses during infusion were comparable to those in spontaneous milk fever. The standardized infusion technique might be useful in future experimental studies.     

Plasma free cortisol concentrations in dogs with hyperadrenocorticism.

Unbound or free cortisol constitutes a small fraction of total plasma cortisol, but is believed to represent the biologically active portion of this circulating glucocorticoid. We tested the hypothesis that the percentage free cortisol was altered in plasma from dogs with hyperadrenocorticism, which could account for a greater target tissue response to this circulating hormone. The percentage free cortisol in plasma samples from human beings, healthy dogs, and dogs with hyperadrenocorticism was estimated, using centrifugal ultrafiltration-dialysis. Total cortisol concentrations were determined by use of radioimmunoassay. Total cortisol concentrations appeared greater in plasma from human beings than in plasma from either group of dogs. However, the percentage free cortisol was lower in plasma from human beings, resulting in a calculated concentration of free cortisol that was quite similar between plasma from human beings and healthy dogs. Total plasma cortisol concentrations were greater (P less than 0.01) in samples from dogs with hyperadrenocorticism (190 +/- 113 nmol/L; mean +/- SD) than in healthy dogs (102 +/- 85 nmol/L), but the percentage free cortisol was not different between these 2 groups (dogs with hyperadrenocorticism, 16 +/- 9%; healthy dogs, 13 +/- 6%). However, plasma free cortisol concentrations (product of total and the percentage of free cortisol) were greater (P less than 0.01) in samples from dogs with hyperadrenocorticism (36 +/- 41 nmol/L) than in those from healthy dogs (16 +/- 9 nmol/L). Significant (P less than 0.001) positive linear relationships were found between total cortisol concentrations and percentage free cortisol in plasma samples from healthy dogs and dogs with hyperadrenocorticism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma cortisol concentrations following cortisone infusion in dogs before and after treatment with cortisone acetate

OBJECTIVE: To evaluate effects of iatrogenic hyperadrenocorticism on plasma cortisol concentrations produced by an infusion of hydrocortisone in dogs. PROCEDURE: Plasma cortisol concentrations were measured regularly during a 6 h infusion of hydrocortisone sodium succinate at two dose rates. The infusions were performed before and after treatment for 30 d with oral cortisone acetate at 10 mg/kg/24 h, divided thrice daily. Adrenal activity during the experimental period was assessed by weekly ACTH stimulation tests. RESULTS: Both infusion rates produced lower plasma cortisol concentrations after treatment for 30 d with cortisone. CONCLUSION: Prior exposure to high concentrations of glucocorticoids may result in accelerated metabolism of glucocorticoids administered subsequently. This may necessitate increased dosages when using glucocorticoids to support inadequate adrenal function.     

Plasma cortisol responses to three cortico-trophic preparations in normal dogs

Objective To compare cortisol responses to three corticotrophic preparations in normal dogs.
Animals Eight clinically normal dogs (four intact males, four intact females) of medium size.
Procedures Each dog received four treatments on four separate occasions in a duplicated Latin square pattern. Treatments were two adrenocorticotrophin (ACTH) preparations given intramuscularly at 2.2 U/kg, one of the ACTH preparations given intramuscularly at 1 U/kg and a synthetic polypeptide with ACTH-like activity (tetracosactrin, cosyntropin) given intravenously at 5 μg/kg. Plasma samples were taken for cortisol assay before and at 0.5, 1, 2 and 4 h after treatment.
Results Plasma cortisol concentrations were similar with the two ACTH preparations and at both dose rates. Tetracosactrin produced smaller mean peak cortisol concentrations, which tended to occur earlier than with ACTH, and smaller values for the area under the curve of plasma cortisol concentration from zero time to 4 h.
Conclusion The findings suggest that canine adrenal function can be tested adequately by giving ACTH intramuscularly at 1 U/kg and measuring plasma cortisol in samples taken at 0 and 2 h, or by giving tetracosactrin intravenously at 5 μg/kg and determining cortisol concentration at 0 and 1 h.     

Glucose and cortisol concentrations in cows treated with a slowly-absorbed betamethasone suspension

A slowly-absorbed aqueous suspension of betamethasone, intended for use in the induction;of parturition, was administered to 10 cows. Each cow received 2ml (mean individual dose, 44.4 +/- 0.5microg/kg) by subcutaneous injection. Plasma samples were collected on six occasions over a seven-day period before treatment and on 21 occasions over a 29 day period after treatment. The mean concentration of betamethasone in plasma, as measured by radioimmunoassay, peaked at 0.6ng/ml24 hours after injection and was detectable for four days. Depression of the endogenous cortisol levels, as recorded with other long-acting synthetic glucocorticoids, was observed with this preparation of betamethasone. Plasma glucose was significantly elevated for eight days after betamethasone administration.     

Plasma endogenous ACTH concentrations and plasma cortisol responses to synthetic ACTH and dexamethasone sodium phosphate in healthy cats

Plasma cortisol responses of 19 healthy cats to synthetic ACTH and dexamethasone sodium phosphate (DSP) were evaluated. After administration of 0.125 mg (n = 5) or 0.25 mg (n = 6) of synthetic ACTH, IM, mean plasma cortisol concentrations increased significantly (P less than 0.05) at 15 minutes, reached a peak at 30 minutes, and decreased progressively to base-line values by 120 minutes. There was no significant difference (P greater than 0.05) between responses resulting from the 2 dosage rates. After administration of 1 mg of DSP/kg of body weight, IV (n = 7), mean plasma cortisol concentrations decreased at postadministration hour (PAH) 1, and were significantly lower than control cortisol concentrations at PAH 4, 6, 8, 10, and 12 (P less than 0.01). Administration of 0.1 mg of DSP/kg, IV (n = 8) or 0.01 mg of DSP/kg, IV (n = 14) induced results that were similar, but less consistent than those after the 1 mg of DSP/kg dosage. Mean plasma cortisol concentrations returned to base-line values by PAH 24. There was not a significant difference between the 3 doses (P greater than 0.05) at most times. Measurement of endogenous ACTH in 16 healthy cats revealed plasma ACTH of less than 20 to 61 pg/ml. Seemingly, administration of synthetic ACTH consistently induced a significant (P less than 0.05) adrenocortical response in healthy cats. On the basis of time-response studies, post-ACTH stimulation cortisol samples should be collected at 30 minutes after ACTH administration to ensure detection of peak adrenocortical response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma progesterone and gonadotrophin concentrations following norgestomet treatment with and without cloprostenol in beef cows

Twelve Hereford cross Friesian cows received subcutaneous implants containing 6 mg norgestomet and intramuscular injections of 5 mg oestradiol valerate and 3 mg norgestomet. Six of the cows also received 0.5 mg cloprostenol eight days later and all implants were removed on day 9. When treatment was commenced between days 3 and 5 of the ovarian cycle, luteal function was not prevented although the luteal phase was shortened in some cases. When treatment was commenced between days 8 and 14 of the cycle progesterone concentrations remained above basal levels for five to seven days. Cows with corpora lutea that were given cloprostenol underwent rapid luteolysis. It is concluded that oestradiol valerate does not control luteal function adequately, particularly if administered early in the cycle, and this may explain failure of oestrus synchronisation in some cases. Administration of prostaglandin 24 hours before norgestomet implant removal may improve the degree of oestrus synchronisation in groups of cyclic cows.     

Plasma glucose and cortisol responses to exogenous insulin in fasted donkeys

Susceptibility to equine hyperlipaemia is increased by poor food intake. To assess the contribution of changes in insulin sensitivity, plasma glucose and cortisol responses to an intravenous insulin challenge (0·4 kg⁻¹ bodyweight) were compared with those observed after saline administration in six donkeys fasted either overnight or for three days. Three days of fasting decreased both the rate of insulin-induced hypoglycemia and the maximal hypoglycemic response. A transitory increase in plasma cortisol which peaked within one to four hours of insulin administration was observed in three of the six overnight-fasted donkeys and in all of the three-day fasted donkeys; inter-animal variation appeared to exist in the responsiveness of the hypothalamic-pituitary-adrenocortical ( ) axis to stimulation by insulin-induced hypoglycemia. Fasting is likely to present a risk of equine hyperlipaemia, at least in part, by the reduction in tissue sensitivity to the glucoregulatory action of insulin.     

Protein expression in dairy cows with and without subclinical hypocalcaemia

AIM: To determine differences in plasma proteomic profiles between healthy cows and those with subclinical hypocalcaemia within 12 hours after calving, and thereby explore the underlying biological mechanism of subclinical hypocalcaemia in dairy cows.

METHODS: Plasma samples were collected within 6 hours of calving from Holstein cows on a farm in Heilongjiang, China; 32 with subclinical hypocalcaemia (plasma calcium concentration 1.38–2.00?mmol/L and no clinical signs) and 59 control cows (plasma calcium concentration 2.10–2.8?mmol/L). Plasma samples were applied to weak cationic exchange protein chips for protein profiling by surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS), and the data were analysed using the PBS-IIC system. The amplitude of peaks for the two groups were compared using the Wilcoxon sum-rank test, and the mass-to-charge ratio of the peaks that differed was used to identify peptide fragments using the Swiss-Prot protein database.

RESULTS: Seven peaks were identified in the subclinical hypocalcaemia group that differed from those of the control group (p<0.001), that represented six unique proteins. Expression of serum albumin, fibrinogen alpha chain, amyloid beta A4 proteins and neurosecretory protein VGF were increased, and expression of apolipoprotein A-II and serum amyloid A proteins were decreased in the subclinical hypocalcaemic cows compared with control cows.

CONCLUSION: Use of SELDI-TOF-MS technology can effectively identify differences in plasma protein expression patterns in cows with subclinical hypocalcaemia. Neurosecretory protein VGF and amyloid beta A4 protein might represent useful biomarkers for diagnosis of subclinical hypocalcaemia.     

Plasma cortisol concentrations in normal dogs given hydrocortisone sodium succinate

OBJECTIVE: To evaluate the effects on plasma cortisol concentration of a continuous infusion of a readily available steroid with equipotent glucocorticoid and mineralocorticoid effects. PROCEDURE: Plasma cortisol concentrations were measured before and regularly after hydrocortisone sodium succinate was administered as a continuous intravenous infusion over 6 h at 0.32 and 0.65 mg kg-1 h-1 to 12 healthy dogs weighing 12 to 22 kg. RESULTS: The infusion at both does rates produced significant and stable increases in plasma cortisol concentrations. The plateau concentrations produced by the large and small doeses were respectively above and below plasma cortisol concentrations likely to provide adequate glucocorticoid and mineralocorticoid activity in stressed dogs with significantly decreased adrenal function. CONCLUSION: This paper presents information regarding the changes in plasma cortisol concentrations in 12 normal dogs given an hydrocortisone sodium succinate infusion at two dose rates. The marked and continuous increase in plasma cortisol concentrations suggests a continuous HSS infusion may be a possible alternative to desoxycorticosterone acetate and dexamethasone in the treatment of acute adrenal dysfunction.     

Plasma leptin responses to lipopolysaccharide and tumor necrosis factor alpha in cows

Peripheral administration of bacterial lipopolysaccharide (LPS) and various inflammatory cytokines to rodents is known to raise plasma levels of leptin, a potent satiety factor secreted from adipocytes, implying a role of leptin in endotoxin-induced anorexia. We previously reported no effect of LPS on serum leptin levels in sheep, despite marked anorexia and fever. Our results suggest that leptin might not be involved in the endotoxin-induced anorexia in ruminants. To test this idea, in the present study, plasma leptin levels were measured during acute experimental endotoxemia in Holstein cows. Intravenous injection of LPS induced anorexia accompanied with increases in plasma levels of cortisol and insulin, all of which are known to stimulate leptin secretion in rodent and human, while it did not affect plasma leptin levels at all in cows. Similar results were also obtained after injection of recombinant bovine tumor necrosis factor alpha. These results indicate that plasma leptin levels in cows during acute endotoxemia are differentially regulated from those in rodents, and that leptin might not be involved in the endotoxin-induced anorexia in ruminants.