Cortisol concentrations following stimulation of healthy and adrenzpathic dogs with two doses of tetracosactrin

Abstract

A prospective study was undertaken to compare intravenous tetracosactrin at doses of 5 microg/kg and 250 microg for diagnosing hyperadrenocorticism in dogs. Both healthy dogs and dogs with pituitary-dependent hyperadrenocorticism were evaluated with the two doses of the drug, and serum cortisol concentrations were compared at 60 minutes post-stimulation. Some of the dogs had additional samples taken at 90 and 120 minutes. For four dogs with hyperadrenocorticism, timed samples were also obtained at 150, 180 and 240 minutes post-injection. Cortisol concentrations 60 minutes after stimulation with either 5 microg/kg or 250 microg intravenous tetracosactrin were similar for both healthy dogs and dogs with hyperadrenocorticism. The lower dose can therefore be used for diagnosing hyperadrenocorticism in dogs.

Adrenal response to the low dose ACTH stimulation test and the cortisol-to-adrenocorticotrophic hormone ratio in canine babesiosis

“…This has been illustrated in canine studies which produced similar 60 min ACTH-stimulated cortisol concentrations, despite using ACTH doses ranging from 1 g/kg to 250 g/dog (Kerl et al, 1999;Frank et al, 2000). It therefore follows that delta cortisol concentrations would be reduced to a greater extent in situations of high basal cortisol concentrations.…”

Hypoadrenocorticism

“…Once treatment has been initiated, it is very difficult if not impossible to confirm the diagnosis without withdrawing treatment for several weeks. No differences in peak cortisol response between dosages of 5 μg/kg or 250 μg/dog have been documented in either healthy dogs or dogs with clinical signs of hypoadrenocorticism; therefore a dose of 5 μg/kg is recommended to decrease the cost of testing (Kerl, 1999;Frank et al, 2000;Behrend et al, 2006;Lathan et al, 2008;Fig. Not all of these products have been directly compared in dogs but they are considered interchangeable.…”

“…The lowest dose of ACTH that stimulates maximal secretion of cortisol in healthy dogs is 0.5 μg/kg (Martin, 2007). Blood samples for measurement of serum cortisol should be collected prior to and 60 to 90 minutes after administration of ACTH (Frank et al, 2000;Frank et al, 2004). A and AA both illustrate the effect of severe hyperkalemia, with the dog in A having a serum potassium concentration of 8.6 mEq/L and the dog in AA a measurement of 9.4 mEq/L.…”

Use of a Low‐Dose ACTH Stimulation Test for Diagnosis of Hypoadrenocorticism in Dogs

“…Previous studies have documented that a dosage of 5 mg/kg of cosyntropin maximally stimulates cortisol secretion from the adrenal cortex of normal dogs and dogs with hyperadrenocorticism. [2][3][4][5] One dog enrolled in the 2nd part of the study had exaggerated responses to ACTH stimulation after administration of both doses of cosyntropin (cortisol concentration after 5 mg/kg, 41.6 mg/dL; after 250 mg/ dog, 29.1 mg/dL). The dog, a 3-year-old spayed female Yorkshire Terrier, was diagnosed with inflammatory bowel disease.…”

“…Previously, this dosage has been evaluated only in healthy dogs and dogs with hyperadrenocorticism. [2][3][4][5] The hypothesis that was tested in this study was that an ACTH stimulation test performed using a dosage of 5 mg/kg cosyntropin produces equivalent results to the standard dose of 250 mg/dog in dogs with suspected hypoadrenocorticism.…”