Intramuscular administration of a low dose of ACTH for ACTH stimulation testing in dogs

OBJECTIVE: To compare adrenal gland stimulation achieved following administration of cosyntropin (5 microg/kg [2.3 microg/lb]) IM versus IV in healthy dogs and dogs with hyperadrenocorticism. DESIGN: Clinical trial. Animals-9 healthy dogs and 9 dogs with hyperadrenocorticism. PROCEDURES: In both groups, ACTH stimulation was performed twice. Healthy dogs were randomly assigned to receive cosyntropin IM or IV first, but all dogs with hyperadrenocorticism received cosyntropin IV first. In healthy dogs, serum cortisol concentration was measured before (baseline) and 30, 60, 90, and 120 minutes after cosyntropin administration. In dogs with hyperadrenocorticism, serum cortisol concentration was measured before and 60 minutes after cosyntropin administration. RESULTS: In the healthy dogs, serum cortisol concentration increased significantly after administration of cosyntropin, regardless of route of administration, and serum cortisol concentrations after IM administration were not significantly different from concentrations after IV administration. For both routes of administration, serum cortisol concentration peaked 60 or 90 minutes after cosyntropin administration. In dogs with hyperadrenocorticism, serum cortisol concentration was significantly increased 60 minutes after cosyntropin administration, compared with baseline concentration, and concentrations after IM administration were not significantly different from concentrations after IV administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in healthy dogs and dogs with hyperadrenocorticism, administration of cosyntropin at a dose of 5 microg/kg, IV or IM, resulted in equivalent adrenal gland stimulation.     

Serum concentrations of cortisol, sex hormones of adrenal origin, and adrenocortical steroid intermediates in healthy dogs following stimulation with two doses of cosyntropin

OBJECTIVE: To compare the effects of 2 doses of cosyntropin (5 microg/kg vs 250 microg, IV) on serum concentrations of cortisol, sex hormones of adrenal origin, and adrenocortical steroid intermediates and determine the optimal sample collection time after adrenal stimulation with cosyntropin. ANIMALS: 10 healthy, privately owned, neutered dogs. PROCEDURE:Dogs were randomly assigned to initially receive cosyntropin at 5 microg/kg or as a total dose of 250 microg, IV. Dogs received the alternate dose 1 to 2 weeks later. Serum was obtained from blood samples collected before (0 minutes) and 30, 60, 90, and 120 minutes after cosyntropin administration. RESULTS:Maximum stimulation of cortisol, androstenedione, progesterone, and 17-hydroxyprogesterone production was achieved at 60 minutes following IV administration of cosyntropin at 5 microg/kg or as a total dose of 250 microg. Serum estradiol concentration did not increase in response to either cosyntropin dose. For all hormones, no significant difference in serum hormone concentrations was found among sample collection times of 0, 30, 60, and 90 minutes when comparing the 2 doses of cosyntropin. CONCLUSIONS AND CLINICAL RELEVANCE: Cosyntropin, when administered at 5 microg/kg, IV, effectively stimulated maximum production of cortisol, sex hormones of adrenal origin, and adrenocortical steroid intermediates at 1 hour after administration.     

Hypothalamic-Pituitary-Adrenal Axis Dysfunction in Hospitalized Neonatal Foals

Background: Transient hypothalamic-pituitary-adrenal (HPA) axis dysfunction occurs frequently in critically ill humans and impacts survival. The prevalence and impact of HPA axis dysfunction in critically ill neonatal foals are not well characterized.
Hypotheses: (1) HPA axis dysfunction occurs in hospitalized neonatal foals, and is characterized by inappropriately low basal serum cortisol concentration or inadequate cortisol response to exogenous adrenocorticotropic hormone (ACTH); (2) hospitalized foals with HPA axis dysfunction have more severe disease and are less likely to survive than hospitalized foals with normal HPA axis function.
Animals: Seventy-two hospitalized foals and 23 healthy age-matched foals.
Methods: Basal ACTH and cortisol concentrations were measured and a paired low-dose (10 μg)/high-dose (100 μg) cosyntropin stimulation test was performed at admission in hospitalized foals. HPA axis dysfunction was defined as (1) an inappropriately low basal cortisol concentration or (2) an inadequate increase in cortisol concentration (delta cortisol) after administration of cosyntropin, with cut-off values for appropriate basal and delta cortisol concentrations determined from results obtained in healthy age-matched foals.
Results: Forty-six percent of hospitalized foals had an inappropriately low basal cortisol concentration and 52% had an inadequate delta cortisol concentration after administration of the 100 μg dose of cosyntropin. An inadequate delta cortisol response to the high (100 μg) dose of cosyntropin was significantly correlated with shock and multiple organ dysfunction syndrome in hospitalized foals, and with decreased survival in a subgroup of septic foals.
Conclusions and Clinical Importance: HPA axis dysfunction occurs frequently in hospitalized neonatal foals, and negatively impacts disease severity and survival.     

Adrenal function in the cat: comparison of the effects of cosyntropin (synthetic ACTH) and corticotropin gel stimulation

The serum cortisol responses of 10 normal cats to natural adrenocorticotrophic hormone (ACTH) gel and synthetic ACTH (cosyntropin) were evaluated and compared. Following administration of either ACTH gel or cosyntropin, mean serum cortisol concentrations increased significantly (P less than 0.05) within 30 minutes and reached a maximal response (2.5 to 10 times basal values) at 90 minutes. The time to reach peak serum cortisol concentrations was variable, however, and occurred sooner after cosyntropin (30 to 60 minutes) than after ACTH gel administration (90 to 180 minutes). While ACTH gel tended to produce a prolonged cortisol response, the effects of cosyntropin were more transient, with serum cortisol concentrations returning to normal range within three hours after injection. Results of this study indicate that the administration of either ACTH gel or cosyntropin consistently produces an adequate adrenocortical response in the cat. Based on the time response studies, post ACTH cortisol samples should be collected 60 to 90 minutes after cosyntropin or 90 to 120 minutes after ACTH gel injection to ensure detection of peak adrenocortical response with either ACTH preparation.     

Evaluation of a low-dose synthetic adrenocorticotropic hormone stimulation test in clinically normal dogs and dogs with naturally developing hyperadrenocorticism.

OBJECTIVE: To determine whether low doses of synthetic ACTH could induce a maximal cortisol response in clinically normal dogs and to compare a low-dose ACTH stimulation protocol to a standard high-dose ACTH stimulation protocol in dogs with hyperadrenocorticism. DESIGN: Cohort study. ANIMALS: 6 clinically normal dogs and 7 dogs with hyperadrenocorticism. PROCEDURE: Each clinically normal dog was given 1 of 3 doses of cosyntropin (1, 5, or 10 micrograms/kg [0.45, 2.3, or 4.5 micrograms/lb] of body weight, i.v.) in random order at 2-week intervals. Samples for determination of plasma cortisol and ACTH concentrations were obtained before and 30, 60, 90, and 120 minutes after ACTH administration. Each dog with hyperadrenocorticism was given 2 doses of cosyntropin (5 micrograms/kg or 250 micrograms/dog) in random order at 2-week intervals. In these dogs, samples for determination of plasma cortisol concentrations were obtained before and 60 minutes after ACTH administration. RESULTS: In the clinically normal dogs, peak cortisol concentration and area under the plasma cortisol response curve did not differ significantly among the 3 doses. However, mean plasma cortisol concentration in dogs given 1 microgram/kg peaked at 60 minutes, whereas dogs given doses of 5 or 10 micrograms/kg had peak cortisol values at 90 minutes. In dogs with hyperadrenocorticism, significant differences were not detected between cortisol concentrations after administration of the low or high dose of cosyntropin. CLINICAL IMPLICATIONS: Administration of cosyntropin at a rate of 5 micrograms/kg resulted in maximal stimulation of the adrenal cortex in clinically normal dogs and dogs with hyperadrenocorticism.     

Hypothalamic-Pituitary-Adrenal Axis Assessment in Healthy Term Neonatal Foals Utilizing a Paired Low Dose/High Dose ACTH Stimulation Test

Background: Hypothalamic-pituitary-adrenal (HPA) axis function is dynamic in the neonatal foal. The paired low dose/high dose cosyntropin (ACTH) stimulation test allows comprehensive HPA axis assessment, but has not been evaluated in neonatal foals.
Hypothesis: Foal age will significantly affect cortisol responses to a paired 10 and 100 μg dose cosyntropin stimulation test in healthy neonatal foals.
Animals: Twenty healthy neonatal foals.
Methods: HPA axis function was assessed in 12 foals at birth and at 12–24, 36–48 hours, and 5–7 days of age. At each age, basal cortisol and ACTH concentrations were measured and cortisol responses to 10 and 100 μg cosyntropin were assessed with a paired ACTH stimulation test protocol. Eight additional 36–48-hour-old foals received saline instead of 10 μg cosyntropin in the same-paired ACTH stimulation test design.
Results: At birth, foals had significantly higher basal cortisol and ACTH concentrations and higher basal ACTH : cortisol ratios compared with foals in all other age groups. A significant cortisol response to both the 10 and 100 μg doses of cosyntropin was observed in all foals. The magnitude of the cortisol response to both doses of cosyntropin was significantly different across age groups, with the most marked responses in younger foals. There was no effect of the paired ACTH stimulation test design itself on cortisol responses.
Conclusions and Clinical Importance: A paired 10 and 100 μg cosyntropin stimulation test can be used to evaluate HPA axis function in neonatal foals. Consideration of foal age is important in interpretation of HPA axis assessment.     

Adrenocorticotropic hormone stimulation tests in healthy foals from birth to 12 weeks of age

The purpose of this study was to investigate total baseline plasma cortisol and adrenocorticotropic hormone (ACTH) concentrations, and ACTH-stimulated cortisol concentrations in foals from birth to 12 wk of age. Plasma (baseline) cortisol and ACTH concentrations were measured in 13 healthy foals at birth and at 1, 2, 3, 4, 5, 7, 10, 14, 21, 28, 42, 56, and 84 d of age. Each foal received cosyntropin (0.1 μg/kg) intravenously. Plasma cortisol concentrations were measured before (baseline), and 30, and 60 min after cosyntropin administration at birth and at 3, 5, 7, 10, 14, 21, 28, 42, 56, and 84 d of age. Compared with baseline, cortisol concentration increased significantly 30 min after administration of cosyntropin on all days. Cortisol concentration was highest at birth, measured at 30 and 60 min after cosyntropin administration, compared with all other days. With the exception of birth measurements, cortisol concentration was significantly higher on day 84, measured at 30 and 60 min after cosyntropin administration, when compared with all other days. Baseline plasma ACTH was lowest at birth when compared with concentrations on days 2, 3, 4, 5, 7, 10, 14, 42, 56, and 84. Administration of 0.1 μg/kg of cosyntropin, IV, reliably induces cortisol secretion in healthy foals. Differences in the magnitude of response to cosyntropin are observed depending on the age of the foal. These data should serve as a reference for the ACTH stimulation test in foals and should be useful in subsequent studies to evaluate the hypothalamic-pituitary-adrenal axis in healthy and critically ill foals.     

Effect of low doses of cosyntropin on serum cortisol concentrations in clinically normal dogs

OBJECTIVE: To determine the lowest of 5 doses of cosyntropin (1.0, 0.5, 0.1, 0.05, or 0.01 microg/kg) administered IV that stimulates maximal cortisol secretion in clinically normal dogs. ANIMALS: 10 clinically normal dogs. PROCEDURES: 5 dose-response experiments were performed in each of the dogs. Each dog received 5 doses of cosyntropin (1.0, 0.5, 0.1, 0.05, and 0.01 microg/kg) IV in random order (2-week interval between each dose). Serum samples for determination of cortisol concentrations were obtained before (baseline) and at 10, 20, 30, 40, 50, 60, 120, and 240 minutes after cosyntropin administration. RESULTS: Compared with baseline values, mean serum cortisol concentration in the study dogs increased significantly after administration of each of the 5 cosyntropin doses. Mean peak serum cortisol concentration was significantly lower after administration of 0.01, 0.05, and 0.1 microg of cosyntropin/kg, compared with findings after administration of 0.5 and 1.0 microg of cosyntropin/kg. After administration of 0.5 and 1.0 microg of cosyntropin/kg, mean peak serum cortisol concentration did not differ significantly; higher doses of cosyntropin resulted in more sustained increases in serum cortisol concentration, and peak response developed after a longer interval. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of cosyntropin IV at a dose of 0.5 microg/kg induced maximal cortisol secretion in healthy dogs. Serum cortisol concentration was reliably increased in all dogs after the administration of each of the 5 doses of cosyntropin. These data should be useful in subsequent studies to evaluate the hypothalamic-pituitary-adrenal axis in healthy and critically ill dogs.     

Use of compounded adrenocorticotropic hormone (ACTH) for adrenal function testing in dogs

Serum cortisol concentrations were measured in five healthy dogs in response to five adrenocorticotropic hormone (ACTH) preparations. Cortisol concentrations were similar at time 0 (pre-ACTH) and at 30 and 60 minutes after injection of all forms of ACTH. However, at 90 and 120 minutes post-ACTH, serum cortisol concentrations were significantly lower following injection of two compounded forms of ACTH. The data showed that injection of four compounded forms of ACTH caused elevations in serum cortisol concentrations of a similar magnitude as cosyntropin in samples collected 60 minutes after administration; but concentrations at later times varied, depending on the type of ACTH used.     

Comparison of the immunoreactive plasma corticotropin and cortisol responses to two synthetic corticotropin preparations (tetracosactrin and cosyntropin) in healthy cats.

Plasma cortisol and immunoreactive (IR)-ACTH responses to 125 micrograms of tetracosactrin and cosyntropin--the formulation of synthetic ACTH available in Europe and the United States, respectively--were compared in 10 clinically normal cats. After administration of tetracosactrin or cosyntropin, mean plasma cortisol concentration reached a peak and plateaued between 60 and 120 minutes, then gradually decreased to values not significantly different from baseline concentration by 5 hours. Mean plasma IR-ACTH concentration reached a maximal value at 15 minutes after administration of tetracosactrin or cosyntropin and was still higher than baseline concentration at 6 hours. Difference between mean plasma cortisol and IR-ACTH concentrations for the tetracosactrin or cosyntropin trials was not significant at any of the sample collection times. Individual cats had some variation in the time of peak cortisol response after administration of either ACTH preparation. About half the cats had peak cortisol concentration at 60 to 90 minutes, whereas the remainder had the peak response at 2 to 4 hours. In general, however, peak cortisol concentration in the cats with delayed response was not much higher than the cortisol concentration at 60 to 90 minutes. Overall, these results indicate that tetracosactrin or cosyntropin induce a comparable, if not identical, pattern of adrenocortical responses when administered to healthy cats.     

Comparison of intravenous and intramuscular routes of administering cosyntropin for corticotropin stimulation testing in cats.

Plasma cortisol and immunoreactive (IR)-ACTH responses to 125 micrograms of synthetic ACTH (cosyntropin) administered IV or IM were compared in 10 clinically normal cats. After IM administration of cosyntropin, mean plasma cortisol concentration increased significantly (P less than 0.05) within 15 minutes, reached maximal concentration at 45 minutes, and decreased to values not significantly different from baseline concentration by 2 hours. After IV administration of cosyntropin, mean plasma cortisol concentration also increased significantly (P less than 0.05) at 15 minutes, but in contrast to IM administration, the maximal cortisol response took longer (75 minutes) and cortisol concentration remained significantly (P less than 0.05) higher than baseline cortisol concentration for 4 hours. Mean peak cortisol concentration (298 nmol/L) after IV administration of cosyntropin was significantly (P less than 0.05) higher than the peak value (248 nmol/L) after IM administration. All individual peak plasma cortisol concentrations and areas under the plasma cortisol response curve were significantly (P less than 0.05) higher after IV administration of cosyntropin than after IM administration. Mean plasma IR-ACTH concentration returned to values not statistically different from baseline by 60 minutes after IM administration of cosyntropin, whereas IR-ACTH concentration still was higher than baseline concentration 6 hours after IV administration. Peak plasma IR-ACTH concentration and area under the plasma IR-ACTH response curve also were significantly (P less than 0.05) higher after IV administration of cosyntropin. Results of the study confirmed that IV administration of cosyntropin induces significantly (P less than 0.05) greater and more prolonged adrenocortical stimulation than does IM administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of a low-dose ACTH stimulation test for diagnosis of hypoadrenocorticism in dogs

BACKGROUND: Although definitive diagnosis of hypoadrenocorticism usually is made by an adrenocorticotrophic hormone (ACTH) stimulation test using 250 microg/dog of synthetic ACTH (cosyntropin/tetracosactrin), increased costs have prompted a search for less-expensive diagnostic methods. HYPOTHESIS: A low-dose ACTH stimulation test (5 microg/kg) will distinguish between dogs with nonadrenal illness and hypoadrenocorticism. Additionally, administration of cosyntropin will not affect the results of another ACTH stimulation test performed 24 hours later. ANIMALS: Eight healthy adult dogs and 29 hospitalized dogs with suspected hypoadrenocorticism. METHODS: In this prospective study, each healthy dog received 4 ACTH stimulation tests. Dogs received either 5 microg/kg or 250 microg/dog of cosyntropin on day 1 and the alternate dose on day 2. The opposite dosing sequence was used after a 2-week washout period (days 15 and 16). Dogs with suspected Addison's disease received 2 ACTH stimulation tests, 24 hours apart, using either a dose of 5 microg/kg cosyntropin or 250 microg/dog on the 1st day and the alternate dose on the 2nd day. RESULTS: In healthy dogs, poststimulation cortisol concentrations on days 2 and 16 and days 1 and 15 were equivalent (90% confidence interval [CI]: 86.7-101.2%). In dogs with suspected Addison's disease, mean (+/-SD) cortisol responses to ACTH in the 5 microg/kg dose (16.2+/-7.7 microg/dL) and 250 microg/dog dose (15.9+/-6.3 microg/dL) were statistically equivalent (90% CI: 91.2-105.4%). CONCLUSIONS AND CLINICAL IMPORTANCE: Low-dose ACTH stimulation testing distinguishes between dogs with nonadrenal illness and hypoadrenocorticism. Additionally, the administration of 2 ACTH stimulation tests on consecutive days does not affect results of the second test.     

Relative adrenal insufficiency in dogs with sepsis

BACKGROUND: A syndrome of relative adrenal insufficiency has been identified in septic humans, and is associated with hypotension and death. Relative adrenal insufficiency is generally associated with basal serum cortisol concentration within or above the reference range and a blunted cortisol response to adrenocorticotropic hormone administration. It is unknown whether relative adrenal insufficiency occurs in septic dogs. HYPOTHESIS: That relative adrenal insufficiency occurs in septic dogs, and that relative adrenal insufficiency is associated with hypotension and mortality. ANIMALS: Thirty-three septic dogs admitted to a small animal intensive care unit. METHODS: Dogs were included in the study if they had a known or suspected infectious disease and had systemic inflammatory response syndrome. Dogs were excluded if they had disease or medication history expected to affect the hypothalamic-pituitary-adrenal axis. Serum cortisol and endogenous plasma adrenocorticotropic hormone concentrations were measured before, and serum cortisol concentration measured 1 hour after, intramuscular administration of 250 microg of cosyntropin/dog. The change in cortisol concentration (delta-cortisol) before and after cosyntropin administration was determined in each dog. RESULTS: Hypotension was associated with lower delta-cortisol values (OR 1.3; CI 1.0-1.9; P = .029). delta-Cortisol cutoff of 3.0 microg/dL was most accurate for predicting hypotension, survival to discharge, and 28-day survival. The rate of death in dogs with delta-cortisol < or = 3 microg/dL was 4.1 times that of dogs with delta-cortisol > 3 microg/dL (RR 4.1; CI 1.5-12.3; P = .01). CONCLUSIONS AND CLINICAL RELEVANCE: Delta-cortisol < or = 3 microg/dL after adrenocorticotropic hormone administration is associated with systemic hypotension and decreased survival in septic dogs.     

Blood arginine vasopressin, adrenocorticotropin hormone, and cortisol concentrations at admission in septic and critically ill foals and their association with survival

BACKGROUND: Sepsis is an important cause for neonatal foal mortality. The hypothalamic-pituitary-adrenal axis (HPAA) responses to sepsis are well documented in critically ill humans, but limited data exist in foals. The purpose of this study was to evaluate the HPAA response to sepsis in foals, and to associate these endocrine changes with survival. HYPOTHESIS: Blood concentrations of arginine vasopressin (AVP), adrenocorticotropin hormone (ACTH), and cortisol will be higher in septic foals as compared with sick nonseptic and healthy foals. The magnitude of increase in hormone concentration will be negatively associated with survival. ANIMALS: Fifty-one septic, 29 sick nonseptic, and 31 healthy foals of < or =7 days of age were included. METHODS: Blood was collected at admission for analysis. Foals with positive blood culture or sepsis score > or =14 were considered septic. Foals admitted with disease other than sepsis and healthy foals were used as controls. AVP, ACTH, and cortisol concentrations were measured using validated immunoassays. RESULTS: AVP, ACTH, and cortisol concentrations were increased in septic foals. Septic nonsurvivor foals (n = 26/51) had higher plasma ACTH and AVP concentrations than did survivors (n = 25/51). Some septic foals had normal or low cortisol concentrations despite increased ACTH, suggesting relative adrenal insufficiency. AVP, ACTH, and cortisol concentrations were higher in sick nonseptic foals compared with healthy foals. CONCLUSIONS AND CLINICAL IMPORTANCE: Increased plasma AVP and ACTH concentrations in septic foals were associated with mortality. Several septic foals had increased AVP : ACTH and ACTH : cortisol ratios, which indicates relative adenohypophyseal and adrenal insufficiency.     

Disposition of oral clarithromycin in foals

Clarithromycin offers numerous advantages over erythromycin and thus, is an attractive alternative for the treatment of Rhodococcus equi infections in foals. The disposition of clarithromycin was investigated in 6 foals after intragastric administration at a dose of 10 mg/kg body weight. Detectable serum concentrations of clarithromycin were found in 3 of 6 foals at 10 minutes and in all foals by 20 minutes post-administration. Time to peak serum concentration (Tmax) was 1.5 hours and peak serum concentration (Cmax) was 0.92+/-0.17 microg/ml. Mean serum concentrations decreased to 0.03 microg/ml at 24 h. No adverse reactions were noted during or after IG administration in any of the foals. Based on the pharmacokinetic parameters, the MIC90 of R. equi isolates, and predicted steady state concentrations, an oral dose of 7.5 mg/kg given every 12 hours would appear appropriate for the treatment of R. equi infections in foals.     

Cortisol response to two different doses of intravenous synthetic ACTH (tetracosactrin) in overweight cats

Fifteen middle-aged to older, overweight cats attending a first-opinion clinic were investigated to rule out hyperadrenocorticism as a cause of their weight problem, using two different protocols for the adrenocorticotropic hormone (ACTH) stimulation test. The cats received intravenous synthetic ACTH (tetracosactrin) at an initial dose of 125 microg; a second test was performed between two and three weeks later, using a dose of 250 microg intravenously. The mean basal serum cortisol concentration was 203 nmol/litre (range 81 to 354 nmol/litre). The highest mean serum cortisol concentration occurred at 60 minutes following the 125 microg dose and at 120 minutes following the 250 microg dose. There was, however, no statistically significant difference between these peak cortisol concentrations attained using either dose of tetracosactrin. A significantly higher mean serum cortisol concentration was attained after the higher dose at the 180 minutes time point, indicating a more prolonged response when compared with the lower dose. The cats were followed up for one year after the initial investigations and none were found to develop hyperadrenocorticism during this time.     

Studies on equine prematurity 2: Post natal adrenocortical activity in relation to plasma adrenocorticotrophic hormone and catecholamine levels in term and premature foals

Adrenocortical and medullary function was investigated during the immediate post natal period in premature and full term foals. High plasma cortisol concentrations were characteristic of the term foals in the first 2 h after birth and these were accompanied by significant arteriovenous differences in plasma cortisol across the umbilical circulation at birth, indicating enhanced adrenal activity before delivery. No such arteriovenous differences were detected in the premature group and post natal changes in plasma cortisol were minimal. The apparent inability of the premature foal adrenal to secrete cortisol was not due to the lack of endogenous adrenocorticotrophic hormone (ACTH) because high levels of this hormone were found immediately after birth in both groups of foals. Tests on the sensitivity of the foal adrenal to exogenous ACTH1-24 (0.125 mg intramuscularly [im]) showed that a maximum response to this hormone could be elicited in term foals on the day of birth. Subsequently basal cortisol levels and the response of the adrenal to ACTH1-24 declined. By contrast, only a slight response was observed following the same dose of ACTH1-24 in the premature group. Exposure to Depot ACTH1-24 over 24 h enhanced the basal secretion of cortisol in both premature and term foals but no consistent response to the same ACTH test dose could be elicited in the former. A wide range of total plasma catecholamine concentrations was observed in both groups of newborn foals. The highest values were seen in acidotic animals and there was a significant inverse relationship between blood pH and total plasma catecholamine level at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)     

ACTH stimulation test in the captive cheetah (Acinonyx jubatus)

Serum cortisol response was assessed in 8 captive cheetahs, of varying ages, after the intravenous administration of 500 microg of tetracosactide (Synacthen Depot, Novartis, Kempton Park) while maintained under general anaesthesia. In addition, 8 cheetahs were anaesthetised and given an equal volume of saline in order to establish baseline cortisol concentrations at similar stages of anaesthesia. A significant difference in the median cortisol concentration measured over time was found following ACTH administration in the ACTH group (P < 0.001). There was no difference between the median cortisol concentrations in the ACTH group at time-points 120, 150 and 180 min after ACTH stimulation (P = 0.867). Thus it appears appropriate to collect serum 120 to 180 min after tetracosactide administration to assess maximal stimulation of the adrenal in the cheetah. No statistically significant rise was seen in the anaesthetised control group following the injection of saline (P = 0.238).     

Steroid hormone concentration profiles in healthy intact and neutered dogs before and after cosyntropin administration

The purpose of this study was to determine steroid hormone concentration profiles in healthy intact and neutered male and female dogs. Seventeen intact female dogs, 20 intact male dogs, 30 spayed female dogs, and 30 castrated male dogs were used in this study. Serum samples were collected before and 1h after cosyntropin administration, and serum concentrations were determined for cortisol, progesterone, 17-OH progesterone (17-OHP), dehydroepiandrosterone sulfate (DHEAS), androstenedione, testosterone, and estradiol. Intact male dogs had greater concentrations of DHEAS, androstenedione, and testosterone. Intact female dogs had greater concentrations of progesterone. There was no significant difference in estradiol concentration among the four groups. Intact male dogs had lower concentrations of cortisol post-stimulation. DHEAS and testosterone did not increase in response to ACTH in intact males, and estradiol concentrations did not increase in response to ACTH in any group. Results from this study will enhance interpretation of suspected adrenal and/or gonadal disorders of dogs. Because estradiol concentrations were similar in all groups of dogs, measuring estradiol may not be a useful diagnostic test. Cortisol concentrations for intact male dogs with hyperadrenocorticism may be lower than those of female or neutered dogs.     

Use of basal serum or plasma cortisol concentrations to rule out a diagnosis of hypoadrenocorticism in dogs: 123 cases (2000-2005)

OBJECTIVE: To determine whether basal serum or plasma cortisol concentration can be used as a screening test to rule out hypoadrenocorticism in dogs. DESIGN: Retrospective case-control study. ANIMALS: 110 dogs with nonadrenal gland illnesses and 13 dogs with hypoadrenocorticism. PROCEDURES: Sensitivity and specificity of basal serum or plasma cortisol concentrations of either 2 microg/dL that are not receiving corticosteroids, mitotane, or ketoconazole are highly unlikely to have hypoadrenocorticism. However, if the basal cortisol concentration is 相似文献