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Objective

To evaluate the biological stability of reconstituted cosyntropin after storage at −20 C for 2, 4, and 6 months.

Design

Prospective study.

Animals

10 clinically normal dogs.

Procedure

Serum cortisol concentrations in dogs were determined before and 1 hour after administration of freshly reconstituted cosyntropin (synthetic ACTH) or cosyntropin that had been reconstituted and stored frozen at −20 C in plastic syringes for 2, 4, and 6 months. Cosyntropin was administered at 5 μg/kg (2.3 μg/lb) of body weight, IV.

Results

Baseline serum cortisol concentrations were similar at each sampling time. Compared with the effects of freshly reconstituted cosyntropin, administration of cosyntropin that had been frozen did not have a significantly different effect on serum cortisol concentrations.

Clinical lmplications

Cosyntropin can be reconstituted and stored frozen at −20 C in plastic syringes for 6 months with no adverse effects on bioactivity of the polypeptide. (J Am Vet Med Assoc 1998;212: 1569–1571)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To investigate the in vitro effect of the combination of lignan enterolactone (ENL) or lignan enterodiol (END) with melatonin on steroid hormone secretion and cellular aromatase content in human adrenal carcinoma cells. Sample—Human adrenocortical carcinoma cells.

Procedures—Melatonin plus ENL or END was added to cell culture medium along with cAMP (100μM); control cells received cAMP alone. Medium and cell lysates were collected after 24 and 48 hours of cultivation. Samples of medium were analyzed for progesterone, 17-hydroxyprogesterone, androstenedione, aldosterone, estradiol, and cortisol concentration by use of radioimmunoassays. Cell lysates were used for western blot analysis of aromatase content.

Results—The addition of ENL or END with melatonin to cAMP-stimulated cells (treated cells) resulted in significant decreases in estradiol, androstenedione, and cortisol concentrations at 24 and 48 hours, compared with concentrations in cells stimulated with cAMP alone (cAMP control cells). The addition of these compounds to cAMP-stimulated cells also resulted in higher progesterone and 17-hydroxyprogesterone concentrations than in cAMP control cells; aldosterone concentration was not affected by treatments. Compared with the content in cAMP control cells, aromatase content in treated cells was significantly lower.

Conclusions and Clinical Relevance—The combination of lignan and melatonin affected steroid hormone secretion by acting directly on adrenal tumor cells. Results supported the concept that this combination may yield similar effects on steroid hormone secretion by the adrenal glands in dogs with typical and atypical hyperadrenocorticism.

Full access
in American Journal of Veterinary Research

SUMMARY

Loline and ergot alkaloids found in endophyte-infected (Acremonium coenophialum) tall fescue (eitf) cause vasoconstriction of equine vessels in vitro. An aggregate risk study was used to evaluate the association between horses exposed to eitf and development of laminitis. Veterinary teaching hospitals participating in the Veterinary Medical Data Base were grouped by whether equine accessions were likely to have been at high, moderate, or low risk for exposure to eitf. From 1980-1990, there were 185,781 accessions, of which 5,536 had diagnosis of laminitis. Proportion of equine accessions with laminitis reported by veterinary teaching hospitals for high, moderate, and low risks, were 3.41, 3.04, and 2.00 cases/100 accessions, respectively (P < 0.0001). Comparison of the proportion of accessions with laminitis in the high- and moderate-risk groups with that in the low-risk group revealed significant differences between risk groups over all months (P = 0.063) and differences from month to month within risk groups (P = 0.0001). If the difference among risk groups is attributed entirely to exposure to eitf, the population-attributable risk is 7 cases/1,000 admissions, or 15% of all admissions for laminitis at veterinary teaching hospitals in our data base. Preliminary data support an association between horses exposed to eitf and increased risk of laminitis; however, studies at the individual animal level are indicated to confirm this hypothesis.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the clinical and endocrine responses of ferrets with adrenocortical disease (ACD) to treatment with a slow-release implant of deslorelin acetate.

Animals—15 ferrets with ACD.

Procedure—Ferrets were treated SC with a single slow-release, 3-mg implant of deslorelin acetate. Plasma estradiol, androstenedione, and 17-hydroxyprogesterone concentrations were measured before and after treatment and at relapse of clinical signs; at that time, the adrenal glands were grossly or ultrasonographically measured and affected glands that were surgically removed were examined histologically.

Results—Compared with findings before deslorelin treatment, vulvar swelling, pruritus, sexual behaviors, and aggression were significantly decreased or eliminated within 14 days of implantation; hair regrowth was evident 4 to 6 weeks after treatment. Within 1 month of treatment, plasma hormone concentrations significantly decreased and remained decreased until clinical relapse. Mean time to recurrence of clinical signs was 13.7 ± 3.5 months (range, 8.5 to 20.5 months). In 5 ferrets, large palpable tumors developed within 2 months of clinical relapse; 3 of these ferrets were euthanatized because of adrenal gland tumor metastasis to the liver or tumor necrosis.

Conclusions and Clinical Relevance—In ferrets with ACD, a slow-release deslorelin implant appears promising as a treatment to temporarily eliminate clinical signs and decrease plasma steroid hormone concentrations. Deslorelin may not decrease adrenal tumor growth in some treated ferrets. Deslorelin implants may be useful in the long-term management of hormone-induced sequelae in ferrets with ACD and in treatment of animals that are considered at surgical or anesthetic risk. (Am J Vet Res 2005;66:910–914)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare the effects of 2 doses of cosyntropin (5 µg/kg vs 250 µg, 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 µg/kg or as a total dose of 250 µg, 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 µg/kg or as a total dose of 250 µg. 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 µg/kg, IV, effectively stimulated maximum production of cortisol, sex hormones of adrenal origin, and adrenocortical steroid intermediates at 1 hour after administration. (Am J Vet Res 2004;65:1631–1633)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of leuprolide acetate, a long-acting gonadotropin-releasing hormone analog, in ferrets with adrenocortical diseases.

Design—Case series.

Animals—20 ferrets with adrenocortical disease diagnosed on the basis of clinical signs and plasma sex hormone concentrations.

Procedure—Ferrets were treated with leuprolide (100 µg, IM, once), and plasma hormone concentrations were measured before and 3 to 6 weeks after treatment.

Results—Leuprolide treatment resulted in significant reductions in plasma estradiol, 17 α-hydroxyprogesterone, androstenedione, and dehydroepiandrosterone concentrations and eliminated or reduced clinical signs associated with adrenocortical disease. Decreases in vulvar swelling, pruritus, and undesirable sexual behaviors and aggression were evident 14 days after treatment; hair regrowth was evident by 4 weeks after treatment. The response to treatment was transitory, and clinical signs recurred in all ferrets. Mean ± SEM time to recurrence was 3.7 ± 0.4 months (range, 1.5 to 8 months).

Conclusions and Clinical Relevance—Results suggest that leuprolide can be safely used to temporarily eliminate clinical signs and reduce sex hormone concentrations in ferrets with adrenocortical diseases. However, the safety of long-term leuprolide use in ferrets has not been investigated, and the long-term effects of leuprolide in ferrets with nodular adrenal gland hyperplasia or adrenal gland tumors are unknown. (J Am Vet Med Assoc 2001;218:1272–1274)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate adrenal sex hormone concentrations in neutered dogs with hypercortisolemia.

Design—Case series.

Animals—11 neutered dogs with hypercortisolemia.

Procedure—Serum samples obtained before and 1 hour after administration of ACTH were evaluated for concentrations of cortisol, progesterone, testosterone, dehydroepiandrosterone sulfate or androstenedione or both, and 17-hydroxyprogesterone.

Results—For all dogs, concentrations of 1 or more adrenal sex hormones were substantially greater than reference range values before or after administration of ACTH. Testosterone concentration was not greater than reference range values in any of the dogs.

Conclusions and Clinical Relevance—Results emphasize the importance of ruling out hypercortisolemia before measuring adrenal sex hormone concentrations as a means of diagnosing adrenal hyperplasia syndrome (alopecia X) in dogs. (J Am Vet Med Assoc 2001;218:214–216)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To characterize the physiologic response to IV bolus injection of glucose and insulin for development of a combined glucose-insulin test (CGIT) in horses.

Animals—6 healthy mares and 1 mare each with pituitary adenoma and urolithiasis.

Procedure—Horses were given a CGIT (glucose, 150 mg/kg; insulin, 0.1 U/kg); results were compared with a singular IV glucose tolerance test (GTT; 150 mg/kg) and a singular IV insulin sensitivity test (IST; 0.1 U/kg). Healthy horses were also given a CGIT after receiving xylazine and undergoing stress.

Results—Physiologically, the CGIT resulted in a 2-phase curve with positive (hyperglycemic) and negative (hypoglycemic) portions; the positive phase came first (250% of baseline at 1 minute). The descending segment declined linearly to baseline by approximately 30 minutes and to a nadir at 58% of baseline by 75 minutes. After a 35-minute valley, a linear ascent to baseline began. Addition of insulin in the CGIT increased glucose utilization by approximately 4.5 times during the positive phase but not during the negative phase. The diseases' effects and experimental inhibition of insulin secretion with xylazine and stress were detectable by use of the 2 phases of the CGIT. Only a single positive phase resulted from the GTT and a single negative phase from the IST.

Conclusions and Clinical Relevance—The CGIT resulted in a consistent, well-defined glycemia profile, which can be disrupted experimentally or by a disease process. The CGIT has clinical potential because it provides integrated information and more information than either the singular GTT or IST. (Am J Vet Res 2005;66:1598–1604)

Full access
in American Journal of Veterinary Research

Objective

To determine the effect of oral melatonin (MT) administration on serum concentrations of sex hormones, prolactin, and thyroxine in dogs.

Design

Prospective study.

Animals

8 male and 8 female adult sexually intact dogs.

Procedure

5 male and 5 female dogs were treated with MT (1.0 to 1.3 mg/kg [0.45 to 0.59 mg/lb] of body weight), PO, every 12 hours for 28 days; the other 6 dogs were used as controls. Blood samples were collected on days 0, 14, and 28, and serum concentrations of estradiol-17β, progesterone, testosterone, androstenedione, 17-hydroxyprogesterone (17-HP), dihydroepiandrostenedione sulfate (DHEAS), prolactin, and thyroxine were determined. On day 5, serum MT concentrations were measured before and periodically for up to 8 hours after MT administration in 4 treated dogs.

Results

Female dogs treated with MT had significant decreases in serum estradiol, testosterone, and DHEAS concentrations between days 0 and 28. Male dogs treated with MT had significant decreases in serum estradiol and 17-HP concentrations between days 0 and 28. Serum MT concentrations increased significantly after MT administration and remained high for at least 8 hours. Prolactin and thyroxine concentrations were unaffected by treatment.

Conclusions and Clinical Relevance

Melatonin is well absorbed following oral administration and may alter serum sex hormone concentrations. (J Am Vet Med Assoc 1999;215:1111–1115)

Free access
in Journal of the American Veterinary Medical Association

Objective—

To evaluate results of a combined dexa-methasone suppression/thyrotropin-releasing hormone (TRH) stimulation test in horses suspected clinically to have a pars intermedia pituitary adenoma (PIPA).

Design—

Case-control study.

Animals—

7 healthy adult horses and 5 horses suspected to have a PIPA.

Procedure—

A baseline blood sample was collected, and dexamethasone (40 μg/kg [18 μg/lb] of body weight, IV) was administered; a second blood sample was collected 3 hours later, and TRH (1.1 mg, IV) was administered; serial blood samples were collected 15, 30, 45, 60, and 90 minutes and 21 hours after TRH administration (24 hours after dexamethasone injection). Cortisol concentration was determined for all blood samples.

Results—

Baseline Cortisol concentration was significantly lower in horses suspected to have a PIPA than in healthy horses. Cortisol concentration was suppressed by dexamethasone in both groups; however, after TRH administration, Cortisol concentration returned to baseline values in horses suspected to have a PIPA, but not in healthy horses. Concentration was still less than the baseline value 24 hours after dexamethasone administration in healthy horses.

Clinical Implications—

The combined dexamethasone suppression/TRH stimulation test may be a useful diagnostic test in horses suspected to have a PIPA. For clinical application, collection of a blood sample 30 minutes after TRH administration is recommended. (J Am Vet Med Assoc 1997;211:79–81)

Free access
in Journal of the American Veterinary Medical Association