Diagnosis of spontaneous hyperadrenocorticism in dogs. Part 2: Adrenal function testing and differentiating tests.

Hyperadrenocorticism is a relatively common endocrine disorder in dogs that has been extensively described. However, its diagnosis remains challenging because there is no true reference standard test, and a myriad factors can affect the diagnostic performance of the commonly used adrenal function tests. Ultimately, the diagnosis is based on a combination of signalment, history and clinical findings, and a variety of diagnostic test results. The second part of this review aims to appraise available data on diagnostic performance of adrenal function tests in naturally occurring canine hyperadrenocorticism.

Mineralocorticoid before glucocorticoid deficiency in a dog with primary hypoadrenocorticism and hypothyroidism.

A dog with an unexpected presentation of primary hypoadrenocorticism was evaluated for clinical signs and electrolyte abnormalities characteristic of Addison's disease. Although the initial adrenocorticotropic hormone (ACTH) stimulation test documented serum cortisol concentrations within the reference range, subsequent assessments confirmed hypoaldosteronism. Mineralocorticoid replacement promptly normalized electrolytes and transiently improved clinical illness. Six weeks after initial ACTH stimulation testing, the dog became glucocorticoid deficient. Concurrent primary hypothyroidism was also documented. Hypoaldosteronism preceding hypocortisolemia is a unique presentation of canine Addison's disease.

Comparison of IV and IM formulations of synthetic ACTH for ACTH stimulation tests in healthy dogs.

BACKGROUND: Two commercially available forms of synthetic ACTH are used to diagnose and monitor hyper- and hypoadrenocorticism in dogs. OBJECTIVE: To compare the biologic activity of the liquid and lyophilized forms of cosyntropin. ANIMALS: Eighteen privately owned healthy dogs were included. METHODS: Dogs were assigned to one of 2 groups of 9 dogs each. Group 1 dogs were tested with the lyophilized product first and the liquid solution 30-60 days later. The Group 2 dogs were tested with the liquid solution first and the lyophilized drug 30-60 days later. For the ACTH stimulation tests, serum samples were collected before and 1 hour after IM administration of 0.25 mg reconstituted lyophilized product or 1 hour after IV administration of 0.25 mg of liquid solution. Cortisol concentrations of all serum samples were measured by use of a commercial cortisol radioimmunoassay. RESULTS: Serum cortisol concentrations before and after ACTH stimulation did not differ significantly between groups (P = .57). In addition, no individual dog had as much as a 20% difference in serum cortisol concentrations after administration of either ACTH formulation. CONCLUSIONS AND CLINICAL IMPORTANCE: Given the lack of significant differences of the ACTH stimulation test results, the lyophilized and liquid solution products can be used interchangeably.

Hyperadrenocorticism in 10 dogs with skin lesions as the only presenting clinical signs.

Ten dogs that had skin lesions as the only presenting signs of hyperadrenocorticism (HAC) and as the owners' primary complaint are described. Dogs were included if the initial examination was for skin disease, there were no signs of systemic illness on initial presentation and there was a confirmed diagnosis of HAC by specific screening tests. Dogs were excluded if they had a severe disease that might interfere with screening tests for HAC or if the screening tests were not diagnostic. There were five males and five females; six dogs were intact. Nine dogs were diagnosed at ≥7 years. Eight dogs weighed ≤10 kg. Alopecia was present in nine dogs. Eight dogs had bacterial pyoderma, five had hyperpigmentation, and four had thin skin. One dog had unresolved dermatophytosis. Skin lesions resolved after treatment in eight dogs. One dog was not treated and one was lost to follow-up. This study showed that skin lesions may be the only clinical signs of HAC. The presence of the more common clinical signs of HAC, such as a non-pruritic, truncal alopecia and/or thin skin, without any systemic signs of HAC and/or the presence of poorly responsive skin infections warrant screening for this disease.

Atypical hypoadrenocorticism in a Birman cat.

A 1-year-old female spayed Birman cat was presented with a history of inappropriate urination and defecation, lethargy, anorexia, and weight loss. After intermittent responses to non-specific therapy she was diagnosed with atypical hypoadrenocorticism from the results of an adrenocorticotropic hormone stimulation test.

[Hyperprogesteronism due to bilateral adrenal carcinomas in a cat with diabetes mellitus]. / Hyperprogesteronismus infolge bilateraler Nebennierenrindenkarzinome bei einer Katze mit Diabetes mellitus.

An 8 year old male castrated Russian Blue cat with polyuria, polydipsia, polyphagia, abdominal enlargement, unkempt and easily epilated hair coat and abdominal alopecia is described. As a first step diabetes mellitus was diagnosed. Further work-up by ultrasonography revealed severe bilateral enlargement of the adrenal glands. Hypercortisolism was suspected and therefore ACTH stimulation test and dexamethasone suppression test were performed. In all samples cortisol concentrations were below the detection limit of the assay used. Various precursor hormones were measured and high progesterone concentrations were found. Histologically, the adrenal masses were characterised as bilateral adrenal carcinomas of the adrenal cortex. The case report demonstrates that adrenal gland tumors are also capable to secrete sex hormones instead of cortisol. Clinical signs of hyperprogesteronism are identical to those of hypercortisolism.

Hyperaldosteronism and hyperprogesteronism in a cat.

UNLABELLED: CLINICAL FINDINGS AND INVESTIGATIONS: A 14-year-old female neutered domestic shorthair cat was referred for investigation of progressive hair loss, muscle wasting and hind limb weakness. Diabetes mellitus had been diagnosed 8 months earlier and was well controlled. Abnormalities on serum biochemistry included persistent mild azotaemia, hypochloridaemia, hypokalaemia, metabolic alkalosis and elevated creatine kinase. Physical examination revealed a pot-bellied appearance, with muscle wasting, marked thinning and fragility of the skin, bilaterally symmetrical alopecia, a gallop rhythm and systolic hypertension (173 mmHg). A large, lobulated left adrenal mass was identified using abdominal ultrasound. CONFIRMATION OF DIAGNOSIS: Primary hyperaldosteronism was diagnosed based on an elevated plasma aldosterone concentration and normal plasma renin activity. Hyperprogesteronism was confirmed by adrenocorticotrophic hormone stimulation test. PRACTICAL RELEVANCE: This is only the second reported case of hyperaldosteronism and hyperprogesteronism in the cat. Clinicians should be alert to the possibility of concurrent hyperaldosteronism and hyperprogesteronism in cats with adrenal tumours showing clinical signs referable to both conditions. The putative mechanism is either increased secretion of aldosterone and progesterone from neoplastic cells of the zona glomerulosa and fasciculata/reticularis, respectively, or increased production of progesterone, as an intermediate in the synthesis of aldosterone, from neoplastic cells of the zona glomerulosa alone.

Baseline plasma cortisol and ACTH concentrations and response to low-dose ACTH stimulation testing in ill foals.

OBJECTIVE: To evaluate baseline plasma cortisol and ACTH concentrations and responses to low-dose ACTH stimulation testing in ill foals. DESIGN: Cross-sectional study. ANIMALS: 58 ill foals. PROCEDURES: Baseline cortisol and ACTH concentrations and cortisol concentrations after administration of a low dose of cosyntropin were determined within 6 hours after admission. Foals were assigned to 4 groups on the basis of age (

Use of ketoconazole to treat dogs with pituitary-dependent hyperadrenocorticism: 48 cases (1994-2007).

OBJECTIVE: To evaluate the effectiveness of ketoconazole as a treatment for dogs with pituitary-dependent hyperadrenocorticism (PDH). DESIGN: Retrospective case series. ANIMALS: 48 client-owned dogs in which PDH was diagnosed. PROCEDURES: Medical records of dogs with PDH that were treated with ketoconazole were examined. Data collected from each record included signalment, clinical signs, results of ACTH stimulation tests before and after treatment with ketoconazole, serum alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities, dosage of ketoconazole, clinical response, and survival time. RESULTS: 43 of 48 (90%) dogs had evidence of clinical improvement during the treatment period. In all dogs, treatment with ketoconazole resulted in significantly lower serum cortisol concentrations as measured before and after ACTH stimulation testing; 69% (33/48) of serum cortisol concentrations measured after ACTH stimulation were within the reference range. Serum ALP and ALT activities significantly decreased after treatment with ketoconazole. Survival time after diagnosis of PDH ranged from 2 to 61 months (mean, 26.9 months; median, 25 months). CONCLUSIONS AND CLINICAL RELEVANCE: Ketoconazole was a safe and effective option for treating dogs with PDH. Additional research is needed to evaluate the effects of long-term treatment with ketoconazole on adrenal glands.

Evaluation of the low-dose dexamethasone suppression test and ultrasonographic measurements of the adrenal glands in cats with diabetes mellitus.

The objectives of the study were to evaluate the low-dose dexamethasone suppression (LDDS) test and the size of the adrenal glands via ultrasonography in cats with diabetes mellitus. Twenty-two cats were enrolled in the study. In 19 cats, suppression of cortisol concentrations below 5.5 nmol/litre occurred four and eight hours after intravenous administration of dexamethasone (0.1 mg/kg). In one other cat, the cortisol concentration was also below 5.5 nmol/litre at eight hours but was 11.0 nmol/litre at four hours. The results were in agreement with those of healthy cats in a previous study. The cortisol concentrations four and eight hours after administration of dexamethasone did not differ between cats with good glycemic control (n = 8) and those with moderate to poor control (n = 12). The adrenal glands of the diabetic cats were not enlarged compared with those of healthy cats. In two diabetic cats, the LDDS test results were abnormal. One cat had a pituitary adenoma and adrenal glands of normal size as determined by ultrasonography. The size of the adrenal glands of the other cat clearly differed; histological examination of the larger adrenal gland revealed an adrenocortical adenoma. Based on our findings, the results of the LDDS test using 0.1 mg/kg of dexamethasone are normal in cats with diabetes mellitus independent of the quality of glycemic control. In addition, diabetes mellitus does not lead to a measurable increase in the size of the adrenal glands in cats. Further studies are needed to evaluate if the dexamethasone dosage used in this study is useful to diagnose mild form of hypercortisolism.

Comparison of classic hypoadrenocorticism with glucocorticoid-deficient hypoadrenocorticism in dogs: 46 cases (1985-2005).

OBJECTIVE: To compare dogs with glucocorticoid-deficient hypoadrenocorticism (GDH) with those with mineralocorticoid- and glucocorticoid-deficient hypoadrenocorticism (MGDH) and determine prevalence, historical and clinicopathologic markers, and outcome of dogs with GDH. DESIGN: Retrospective case series. ANIMALS: 46 dogs with hypoadrenocorticism. PROCEDURES: Records in the veterinary medical database at Purdue University were searched for dogs in which hypoadrenocorticism had been diagnosed at the Veterinary Teaching Hospital from 1985 to 2005. Data pertaining to signalment, history, a minimum clinicopathologic database, treatment, and outcome were collected. Dogs with hypoadrenocorticism were classified as having MGDH if hyponatremia, hyperkalemia, or both were detected and as having GDH if hyponatremia and hyperkalemia were absent. Dogs were excluded if they had ever been treated with mitotane or had been treated with > 1 dose of corticosteroids within a month prior to the ACTH-stimulation test. RESULTS: 35 dogs with MGDH and 11 dogs with GDH met the inclusion criteria. Dogs with GDH were older at the time of diagnosis and had a longer duration of clinical signs prior to diagnosis than those with MGDH. Dogs with GDH were more likely to be anemic, hypoalbuminemic, and hypocholesterolemic than dogs with MGDH. CONCLUSIONS AND CLINICAL RELEVANCE: GDH was more common than reported in a referral hospital population of dogs with primary hypoadrenocorticism. Definitive diagnosis of GDH remains a clinical challenge. Absence of a stress leukogram in dogs with signs of illness (especially relating to the gastrointestinal tract) warrants further investigation. Most dogs with primary cortisol deficiency do not develop mineralocorticoid deficiency.

Fecal steroid monitoring for assessing gonadal and adrenal activity in the golden eagle and peregrine falcon.

We examined the efficacy of noninvasive monitoring of endocrine function via fecal steroid immunoassays in the golden eagle and peregrine falcon. High-pressure liquid chromatography analyses of fecal glucocorticoid metabolites (fGCM) revealed that minor percentages of immunoreactive fGCM co-eluted with [(3)H]corticosterone in both sexes of the eagle (2.5-2.7%) and falcon (7.5-11.9%). In contrast, most fecal estrogen metabolites in eagle and falcon females co-eluted with radiolabeled estradiol-17beta ([(3)H]; 57.6, 64.6%, respectively) or estrone ([(3)H]; 26.9, 4.1%, respectively). Most fecal progestin metabolite immunoreactivity in the female eagle (24.8%) and falcon (21.7%) co-eluted with progesterone ([(14)C]). Most fecal androgen metabolite immunoreactivity in eagle (55.8%) and falcon (63.7%) males co-eluted with testosterone ([(14)C]). Exogenous adrenocorticotropin hormone induced increased fGCM excretion above pre-treatment in both species, but only significantly (P < 0.05) in the eagle. Both species showed increased fGCM after saline administration, suggesting the detection of 'handling stress.' Both species exhibited enterohepatic and renal recirculation of administered steroids as demonstrated by biphasic and triphasic excretion patterns. Thus, noninvasive fecal hormone monitoring is a valid and promising tool for assessing gonadal and adrenal status in rare and threatened birds-of-prey.

Alopecia in pomeranians and miniature poodles in association with high urinary corticoid:creatinine ratios and resistance to glucocorticoid feedback.

The adrenocortical function of pomeranians and miniature poodles with alopecia was tested by serial measurements of the urinary corticoid:creatinine ratio (uccr) and by an oral low-dose dexamethasone suppression test (lddst) and uccr measurements. In most of the dogs there was day-to-day variation in the uccrs of the 10 sequential urine samples, often with values above or below the upper limit of the range of healthy control dogs. In 22 alopecic pomeranians the basal uccrs were significantly higher than in 18 non-alopecic pomeranians, and the values of both groups were significantly higher than those of 88 healthy pet dogs. The uccrs of 12 alopecic miniature poodles were significantly higher than those of healthy dogs. In 12 alopecic pomeranians and eight alopecic miniature poodles the oral lddst revealed increased resistance to dexamethasone. In six non-alopecic pomeranians the uccrs after the administration of dexamethasone were not significantly different from those in seven healthy dogs at the same time. In an oral high-dose dexamethasone suppression test, using 0.1 mg dexamethasone/kg bodyweight, the uccrs of seven alopecic pomeranians and five alopecic miniature poodles decreased to low levels.

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).

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.

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.

Changes in the fecal concentrations of cortisol and androgen metabolites in captive male jaguars (Panthera onca) in response to stress

In the present study we determined the efficacy of the measurement of fecal cortisol and androgen metabolite concentrations to monitor adrenal and testicular activity in the jaguar (Panthera onca). Three captive male jaguars were chemically restrained and electroejaculated once or twice within a period of two months. Fecal samples were collected daily for 5 days before and 5 days after the procedure and stored at -20ºC until extraction. Variations in the concentrations of cortisol and androgen metabolites before and after the procedure were determined by solid phase cortisol and testosterone radioimmunoassay and feces dry weight was determined by drying at 37ºC for 24 h under vacuum. On four occasions, fecal cortisol metabolite levels were elevated above baseline (307.8 ± 17.5 ng/g dry feces) in the first fecal sample collected after the procedure (100 to 350 percent above baseline). On one occasion, we did not detect any variation. Mean (± SEM) fecal androgen concentration did not change after chemical restraint and electroejaculation (before: 131.1 ± 26.7, after: 213.7 ± 43.6 ng/g dry feces). These data show that determination of fecal cortisol and androgen metabolites can be very useful for a noninvasive assessment of animal well-being and as a complement to behavioral, physiological, and pathological studies. It can also be useful for the study of the relationship between adrenal activity and reproductive performance in the jaguar.

Changes in the fecal concentrations of cortisol and androgen metabolites in captive male jaguars (Panthera onca) in response to stress.

In the present study we determined the efficacy of the measurement of fecal cortisol and androgen metabolite concentrations to monitor adrenal and testicular activity in the jaguar (Panthera onca). Three captive male jaguars were chemically restrained and electroejaculated once or twice within a period of two months. Fecal samples were collected daily for 5 days before and 5 days after the procedure and stored at -20 degrees C until extraction. Variations in the concentrations of cortisol and androgen metabolites before and after the procedure were determined by solid phase cortisol and testosterone radioimmunoassay and feces dry weight was determined by drying at 37 degrees C for 24 h under vacuum. On four occasions, fecal cortisol metabolite levels were elevated above baseline (307.8 +/- 17.5 ng/g dry feces) in the first fecal sample collected after the procedure (100 to 350% above baseline). On one occasion, we did not detect any variation. Mean (+/- SEM) fecal androgen concentration did not change after chemical restraint and electroejaculation (before: 131.1 +/- 26.7, after: 213.7 +/- 43.6 ng/g dry feces). These data show that determination of fecal cortisol and androgen metabolites can be very useful for a noninvasive assessment of animal well-being and as a complement to behavioral, physiological, and pathological studies. It can also be useful for the study of the relationship between adrenal activity and reproductive performance in the jaguar.

Urinary corticoid:creatinine ratios in healthy pet dogs after oral low-dose dexamethasone suppression tests.

Eleven dogs were used in a trial to find a suitable dose of dexamethasone for an oral dexamethasone suppression test for the diagnosis of hyperadrenocorticism. Basal urinary corticoid:creatinine ratios were established in all 11 and then groups of seven were given oral doses of 0.02, 0.01 or 0.0075 mg dexamethasone/kg bodyweight and urine samples were collected at two-hour intervals from 08.00 to 22.00. The doses of 0.02 and 0.01 mg/kg consistently suppressed their urinary corticoid:creatinine ratios measured at 16.00 by a mean of more than 50 per cent and those of individual dogs to less than 1.0 x 10(-6), whereas the dose of 0.0075 mg/kg did not.

Evidence for chronic stress in captive but not free-ranging cheetahs (Acinonyx jubatus) based on adrenal morphology and function.

The cheetah (Acinonyx jubatus) is highly endangered because of loss of habitat in the wild and failure to thrive in captivity. Cheetahs in zoos reproduce poorly and have high prevalences of unusual diseases that cause morbidity and mortality. These diseases are rarely observed in free-ranging cheetahs but have been documented in cheetahs that have been captured and held in captive settings either temporarily or permanently. Because captivity may be stressful for this species and stress is suspected as contributing to poor health and reproduction, this study aimed to measure chronic stress by comparing baseline concentrations of fecal corticoid metabolites and adrenal gland morphology between captive and free-ranging cheetahs. Additionally, concentrations of estradiol and testosterone metabolites were quantified to determine whether concentrations of gonadal steroids correlated with corticoid concentration and to assure that corticosteroids in the free-ranging samples were not altered by environmental conditions. Concetntrations of fecal corticoids, estradiol, and testosterone were quantified by radioimmunoassay in 20 free-ranging and 20 captive cheetahs from samples collected between 1994 and 1999. Concentrations of baseline fecal corticoids were significantly higher (p = 0.005) in captive cheetahs (196.08 +/- 36.20 ng/g dry feces) than free-ranging cheetahs (71.40 +/- 14.35 ng/g dry feces). Testosterone concentrations were lower in captive male cheetahs (9.09 +/- 2.84 ng/g dry feces) than in free-ranging cheetahs (34.52 +/- 12.11 ng/g dry feces), which suggests suppression by elevated corticoids in the captive males. Evidence for similar sulppression of estradiol concentrations in females was not present. Adrenal corticomedullary ratios were determined on midsagittal sections of adrenal glands from 13 free-ranging and 13 captive cheetahs obtained between 1991 and 2002. The degree of vacuolation of cortical cells in the zona fasciculata was graded for each animal. Corticomedullary ratios were larger (p = 0.05) in captive cheetahs; however, there was no difference (p = 0.31) in the degree of corticocyte vacnolation between the two populations. These data proxile both mnorphologic and functional evidence suggestive of chronic stress in captive cheetahs. Further research into the role of hypercortisolemia in the pathogenesis of the reproductive abnormalities and unusual diseases of captive cheetahs is needed.