Altered Serum Thyrotropin Concentrations in Dogs with Primary Hypoadrenocorticism before and during Treatment.

BACKGROUND: Thyrotropin (TSH) can be increased in humans with primary hypoadrenocorticism (HA) before glucocorticoid treatment. Increase in TSH is a typical finding of primary hypothyroidism and both diseases can occur concurrently (Schmidt's syndrome); therefore, care must be taken in assessing thyroid function in untreated human patients with HA. OBJECTIVE: Evaluate whether alterations in cTSH can be observed in dogs with HA in absence of primary hypothyroidism. ANIMALS: Thirty dogs with newly diagnosed HA, and 30 dogs in which HA was suspected but excluded based on a normal ACTH stimulation test (controls) were prospectively enrolled. METHODS: cTSH and T4 concentrations were determined in all dogs and at selected time points during treatment (prednisolone, fludrocortisone, or DOCP) in dogs with HA. RESULTS: cTSH concentrations ranged from 0.01 to 2.6 ng/mL (median 0.29) and were increased in 11/30 dogs with HA; values in controls were all within the reference interval (range: 0.01-0.2 ng/dL; median 0.06). There was no difference in T4 between dogs with increased cTSH (T4 range 1.0-2.1; median 1.3 µg/dL) compared to those with normal cTSH (T4 range 0.5-3.4, median 1.4 µg/dL; P=0.69) and controls (T4 range 0.3-3.8, median 1.8 µg/dL; P=0.35). After starting treatment, cTSH normalized after 2-4 weeks in 9 dogs and after 3 and 4 months in 2 without thyroxine supplementation. CONCLUSIONS AND CLINICAL RELEVANCE: Evaluation of thyroid function in untreated dogs with HA can lead to misdiagnosis of hypothyroidism; treatment with glucocorticoids for up to 4 months can be necessary to normalize cTSH.

Lack of association between clinical signs and laboratory parameters in dogs with hyperadrenocorticism before and during trilostane treatment.

INTRODUCTION: Trilostane therapy, the treatment of choice for pituitary- dependent hyperadrenocorticism (HAC) in dogs, is monitored by assessing resolution of clinical signs and measuring adrenocortical reserve capacity with an ACTH-stimulation test. The aim of this prospective study was to evaluate agreement between clinical signs reported by owners and cortisol or ACTH concentrations before and during trilostane therapy (starting dose 1-2 mg/kg once daily). A questionnaire on signs of HAC was used and a clinical score calculated as the sum of the 9 questions. Eighteen questionnaires at diagnosis and 97 during therapy were filled out by owners of 32 dogs. An ACTH-stimulation test was performed at each reevaluation. There were weak correlations between abdominal girth, appetite or weight gain and cortisol concentrations during therapy. However, the clinical score did not correlate with cortisol or cACTH values. In 50% of dogs, trilostane application had to be changed from once daily to twice daily during the study. Clinical signs reported by owners matched poorly with cortisol or cACTH concentrations at any time point. If low-dose trilostane is used, treatment frequency often has to be increased.

INTRODUCTION: Le traitement au trilostane, médicament de choix dans les cas d'hyperadrénocorticisme hypophyso-dépendant chez le chien, est évalué sur la base de la disparition des symptômes cliniques et des résultats des tests de stimulation à l'ACTH. Le but de la présente étude prospective était de comparer les symptômes cliniques (évalués par les propriétaires) avec les concentrations de cortisol et d'ACTH endogène avant et durant un traitement au trilostane (dose initiale 1­2 mg/kg, 1× par jour). On a utilisé un questionnaire composé de 9 questions relatives aux symptômes cliniques sur la base desquels on a calculé un score clinique total. Dix-huit questionnaires ont été remplis au moment du diagnostic et 97 durant le traitement par les propriétaires de 32 chiens. Un test de stimulation à l'ACTH a été réalisé lors de chaque contrôle. Il existait de faibles corrélations entre le périmètre abdominal, l'appétit et la prise de poids et les taux de cortisol durant le traitement. Le score clinique total n'était toutefois pas corrélé avec les concentrations de cortisol ou d'ACTH. Chez la moitié des chiens, la dose de trilostane a du être répartie en deux prises journalières. Les symptômes cliniques jugés par les propriétaires montraient une mauvaise corrélation avec les taux de cortisol et d'ACTH durant le traitement au trilostane. Si on dose ce médicament de façon faible, il y a souvent lieu d'augmenter la fréquence des prises.

Cortisol Response in Healthy and Diseased Dogs after Stimulation with a Depot Formulation of Synthetic ACTH.

BACKGROUND: The ACTH stimulation test is used to evaluate the adrenocortical reserve. Recently, the availability of the synthetic ACTH formulation was limited, causing major problems in clinical practice. OBJECTIVES: The objective of this study was to evaluate poststimulation peak cortisol concentrations and the duration of the stimulatory effect of a depot ACTH preparation in dogs. ANIMALS: Twenty-two healthy dogs, 10 dogs with suspected hypoadrenocorticism (HA) and 15 dogs with suspected hyperadrenocorticism (HC). METHODS: Prospective study. An ACTH stimulation test using a synthetic depot tetracosactide, administered intramuscularly (5 µg/kg or at least 0.1 mL) was performed. Blood samples for determination of cortisol were taken immediately before and 1, 2, 3, 4, 6, and 24 hours after stimulation. RESULTS: Peak cortisol concentrations were reached after 2-4 hours in all dogs. Cortisol concentrations 1 hour after stimulation were >9 µg/dL in all healthy dogs and >5 µg/dL in all dogs in which HA was excluded. None of the dogs with HA showed a cortisol-increase above the detection-limit of the assay. After 6 hours, cortisol concentrations had decreased in the healthy and HC group and were back to baseline after 24 hours. CONCLUSIONS AND CLINICAL IMPORTANCE: The depot formulation can be used in place of the short-acting ACTH to evaluate the adrenocortical reserve. Blood for peak cortisol concentrations should be drawn 3 hours after stimulation in cases in which HC is suspected; in HA-suspected cases, blood sampling can take place after 1 hour. As the stimulatory effect is gone after 24 hours, interference with other hormonal tests is unlikely after that time.

Evaluation of the Cortisol-to-ACTH Ratio in Dogs with Hypoadrenocorticism, Dogs with Diseases Mimicking Hypoadrenocorticism and in Healthy Dogs.

BACKGROUND: The adrenocorticotropic hormone (ACTH) stimulation test is the gold standard for diagnosing hypoadrenocorticism (HA) in dogs. However, problems with the availability of synthetic ACTH (tetracosactrin/cosyntropin) and increased costs have prompted the need for alternative methods. OBJECTIVES: To prospectively evaluate the cortisol-to-ACTH ratio (CAR) as a screening test for diagnosing canine HA. ANIMALS: Twenty three dogs with newly diagnosed HA; 79 dogs with diseases mimicking HA; 30 healthy dogs. METHODS: Plasma ACTH and baseline cortisol concentrations were measured before i.v. administration of 5 µg/kg ACTH in all dogs. CAR was calculated and the diagnostic performance of ACTH, baseline cortisol, CAR and sodium-to-potassium ratios (SPRs) was assessed based on receiver operating characteristics (ROC) curves calculating the area under the ROC curve. RESULTS: The CAR was significantly lower in dogs with HA compared to that in healthy dogs and in those with diseases mimicking HA (P < .0001). There was an overlap between HA dogs and those with HA mimicking diseases, but CAR still was the best parameter for diagnosing HA (ROC AUC 0.998), followed by the ACTH concentration (ROC AUC 0.97), baseline cortisol concentration (ROC AUC 0.96), and SPR (ROC AUC 0.86). With a CAR of >0.01 the diagnostic sensitivity and specificity were 100% and 99%, respectively. CONCLUSION AND CLINICAL IMPORTANCE: Calculation of the CAR is a useful screening test for diagnosing primary HA. As a consequence of the observed overlap between the groups, however, misdiagnosis cannot be completely excluded. Moreover, additional studies are needed to evaluate the diagnostic reliability of CAR in more dogs with secondary HA.

Urinary and plasma catecholamines and metanephrines in dogs with pheochromocytoma, hypercortisolism, nonadrenal disease and in healthy dogs.

BACKGROUND: Diagnosis of pheochromocytoma (PC) is based on a combination of clinical suspicion, finding an adrenal mass, increased plasma, and urine concentrations of catecholamine metabolites and is finally confirmed with histopathology. In human medicine, it is controversial whether biochemically testing plasma is superior to testing urine. OBJECTIVES: To measure urinary and plasma catecholamines and metanephrines in healthy dogs, dogs with PC, hypercortisolism (HC), and nonadrenal diseases (NAD) and to determine the test with the best diagnostic performance for dogs with PC. ANIMALS: Seven PC dogs, 10 dogs with HC, 14 dogs with NAD, 10 healthy dogs. METHODS: Prospective diagnostic clinical study. Urine and heparin plasma samples were collected and stored at -80°C before analysis using high-pressure liquid chromatography (HPLC) coupled to electrochemical detection or tandem mass spectrometry were performed. Urinary variables were expressed as ratios to urinary creatinine concentration. RESULTS: Dogs with PC had significantly higher urinary normetanephrine and metanephrine:creatinine ratios and significantly higher plasma-total and free normetanephrine and plasma-free metanephrine concentrations compared to the 3 other groups. There were no overlapping results of urinary normetanephrine concentrations between PC and all other groups, and only one PC dog with a plasma normetanephrine concentration in the range of the dogs with HC and NAD disease. Performances of total and free plasma variables were similar. Overlap of epinephrine and norepinephrine results between the groups was large with both urine and plasma. CONCLUSION AND CLINICAL IMPORTANCE: Measurement of normetanephrine is the preferred biochemical test for PC and urine was superior to plasma.

Use of plasma renin activity to monitor mineralocorticoid treatment in dogs with primary hypoadrenocorticism: desoxycorticosterone versus fludrocortisone.

BACKGROUND: Measurement of plasma renin activity (PRA) is the gold standard for monitoring mineralocorticoid treatment in humans with primary hypoadrenocorticism (PH). OBJECTIVES: To compare PRA in dogs with newly diagnosed PH, dogs with diseases mimicking PH, and healthy dogs, and evaluate measurement of PRA to monitor therapeutic effects in dogs with PH treated with different mineralocorticoids. ANIMALS: Eleven dogs with newly diagnosed PH (group 1), 10 dogs with diseases mimicking PH (group 2), 21 healthy dogs (group 3), 17 dogs with treated PH (group 4). METHODS: In group 1, PRA was measured before treatment and at different times after initiating treatment. In groups 2 and 3, PRA was measured at initial presentation only. In group 4, no baseline PRA was obtained but PRA was measured once or every 1-6 months during treatment. Mineralocorticoid treatment consisted of fludrocortisone acetate (FC) or desoxycorticosterone pivalate (DOCP). RESULTS: Plasma renin activity before treatment was increased in dogs with PH compared to normal dogs and dogs with diseases mimicking PH with median activity of 27, 0.8, and 1.0 ng/mL/h, respectively. In dogs with PH, PRA decreased and normalized with mineralocorticoid treatment using DOCP but not with FC. In dogs treated with DOCP, PRA was lower than in dogs treated with FC. Plasma sodium concentrations were higher and potassium concentrations were lower with DOCP treatment compared to FC treatment. CONCLUSION AND CLINICAL IMPORTANCE: Plasma renin activity is a reliable tool for monitoring mineralocorticoid treatment. DOCP treatment more effectively suppresses PRA compared to FC in dogs with PH.

Urinary corticoid concentrations measured by 5 different immunoassays and gas chromatography-mass spectrometry in healthy dogs and dogs with hypercortisolism at home and in the hospital.

BACKGROUND: Determination of the urinary corticoid-to-creatinine ratio (UCCR) is an important screening test in the diagnosis of hypercortisolism (HC). However, urinary cortisol metabolites interfere with cortisol measurement in immunoassays, leading to decreased specificity. Gas chromatography-mass spectrometry (GC-MS) is considered the gold standard for steroid hormone analysis, because it provides a high level of selectivity and accuracy. OBJECTIVES: To prospectively compare the UCCR of healthy dogs and dogs with HC determined by 5 different immunoassays and by GC-MS and to evaluate the influence of veterinary care on UCCR. ANIMALS: Twenty healthy dogs; 18 dogs with HC. METHODS: Urine was collected in the hospital and again after 6 days at home. Three chemiluminescence immunoassays (Access 2, Beckmann; Immulite 2000, DPC Siemens, with and without trichloromethane extraction) and 2 RIAs (Utrecht in house; Access Beckmann) were used. GC-MS analyses were performed with Agilent 6890N/5973N. Urinary corticoid concentrations were related to urinary creatinine concentrations. RESULTS: Immunoassay results were significantly higher compared to GC-MS results. Evaluation of bias plots and clinical assessment made on the basis of the assay results of each dog indicated substantial disagreement among the assays. Sensitivity varied from 37.5 to 75% and with selected assays was lower in samples from day 6 compared to day 0. GC-MS was not superior to the immunoassays in discriminating healthy from HC dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Considerable variation must be anticipated comparing different urinary cortisol assays. Establishing an assay- and laboratory-specific reference range is critical when using UCCR.

Evaluation of aldosterone concentrations in dogs with hypoadrenocorticism.

BACKGROUND: Some dogs with primary hypoadrenocorticism (HA) have normal sodium and potassium concentrations, a phenomenon called atypical Addison's disease. The assumption that the zona glomerulosa and aldosterone secretion in these dogs are normal seems widely accepted; however, aldosterone measurements are missing in most published cases. OBJECTIVES: To measure aldosterone in dogs with HA with and without electrolyte abnormalities and to determine the time point of aldosterone peak concentrations during ACTH stimulation. ANIMALS: Seventy dogs with HA, 22 dogs with diseases mimicking HA, and 19 healthy dogs. METHODS: Prospective study. Blood samples were taken before and 60 minutes after injection of 250 µg ACTH in all dogs. Additional blood samples were taken 15, 30, and 45 minutes after ACTH in 7 dogs with HA and in 22 with diseases mimicking HA. RESULTS: Baseline and ACTH-stimulated aldosterone was significantly lower in dogs with HA than in the other groups. Aldosterone was low or undetectable in 67/70 dogs with HA independently of sodium and potassium levels. In 3 dogs, sodium/potassium concentrations were normal; in 1 dog, sodium was normal and potassium decreased. In all 4, ACTH-stimulated aldosterone concentrations were below the detection limit of the assay. Aldosterone concentrations were not different at 30, 45, or 60 minutes after ACTH administration. CONCLUSION AND CLINICAL IMPORTANCE: Cortisol and aldosterone secretion is compromised in dogs with HA with and without electrolyte abnormalities. The term atypical Addison's disease, used for dogs with primary HA and normal electrolytes, must be reconsidered; other mechanisms allowing normal electrolyte balance without aldosterone should be evaluated in these dogs.

Comparison of two treatment regimens with trilostane in dogs with pituitary-dependent hyperadrenocorticism.

Trilostane is used to treat dogs with pituitary-dependent hyperadrenocorticism (PDH). In our institution, it was initially dosed based on bodyweight (BW) categories, since April 06 it is dosed per kg BW. Our objectives were to compare effectiveness, number of dose adjustments and side effects of the two dose regimens in dogs with PDH. Dogs of group 1 (28 dogs) received trilostane based on BW categories (< 5 kg, 30 mg; 5 - 20 kg, 60 mg and > 20 kg, 120 mg; SID); dogs of group 2 (20 dogs) received 2 - 5 mg/kg SID. Treatment goal was a post-ACTH cortisol of 1 - 2.5 and 1.5 - 5.4 µg/dl in group 1 and 2, respectively. Starting doses were significantly higher in group 1 and stayed higher until re-check at 4 - 7 months. Baseline and post-ACTH cortisol were significantly decreased compared to pre-treatment at all time points in both groups. Significantly more dogs of group 2 (5/20) needed a dose increase at the first re-check and significantly more dogs of group 1 (10/23) a dose reduction at the last re-check. Intermittent discontinuation was necessary in 25 and 10 % of dogs of group 1 and 2, respectively. We conclude that dosing per kg BW results in comparable clinical improvement, decrease in cortisol, but lower risk of side effects.

Le trilostane est en Suisse le seul médicament enregistré pour le traitement de l'hyperadrénocorticisme hypophysaire. Dans les débuts, le trilostane a été dosé dans notre clinique selon les catégories de poids; depuis avril 2006 nous le dosons en fonction du poids exact. Le but du présent travail était de comparer l'efficacité, le nombre d'ajustement de la dose et les effets secondaires des deux schémas de dosage chez des chiens souffrant d'hyperadrénocorticisme hypophysaire. Chez les chiens du groupe 1 (28 chiens), le dosage à été fait de la façon suivante: < 5 kg, 30 mg; 5 ­ 20 kg, 60 mg; > 20 kg, 120 mg; q24h. Les chiens du groupe 2 (20 chiens) recevaient 2 ­ 5 mg/kg q24h. Le but du traitement était d'atteindre un taux de cortisol après ACTH entre 1 et 2.5 ug/dl dans le groupe 1 et entre 1.5 ­ 5.4 ug/dl dans le groupe 2. Les doses initiales étaient significativement plus hautes dans le groupe 1 et restaient plus élevées jusqu'au contrôle après 4 à 7 mois. Les taux de cortisol basal et après ACTH étaient significativement plus bas par rapport à ceux mesurés avant le traitement dans les 2 groupes, et ce à tout moment. La dose a du être augmentée lors du premier contrôle de façon significativement plus fréquente (5/20) dans le groupe 2. La dose a du être réduite lors des derniers contrôles de façon significativement plus fréquente (10/23) dans le groupe 1. Des interruptions de courte durée du traitement ont été nécessaires chez 25 respectivement 10 % des chiens des groupes 1 réspectivement 2. Le dosage du trilostane en fonction du poids en kilo amène une réponse thérapeutique et une chute du taux de cortisol comparables, mais avec moi s d'effets secondaires.

Evaluation of baseline cortisol, endogenous ACTH, and cortisol/ACTH ratio to monitor trilostane treatment in dogs with pituitary-dependent hypercortisolism.

BACKGROUND: The effectiveness of trilostane treatment is currently monitored by regular ACTH stimulation tests, which are time-consuming and expensive. Therefore, a monitoring system without a stimulation protocol and with less client expense would be preferable. HYPOTHESIS/OBJECTIVES: The aim of our study was to evaluate if baseline cortisol, endogenous ACTH (ACTH) concentration or the baseline cortisol to ACTH ratio (cortisol/ACTH ratio) could replace the ACTH stimulation test. ANIMALS: Forty trilostane-treated dogs with pituitary-dependent hypercortisolism (PDH) were included in this prospective study. METHODS: A total of 148 ACTH stimulation tests and 77 ACTH concentrations and cortisol/ACTH ratios were analyzed. Control of cortisol release was classified according to cortisol concentration after ACTH administration as excessive (<1.5 µg/dL; group 1), adequate (1.5-5.4 µg/dL; group 2), or inadequate (>5.4 µg/dL; group 3). RESULTS: Baseline cortisol concentrations had considerable overlap between excessively, adequately, and inadequately controlled dogs. Only baseline cortisol >4.4 µg/dL (in 12% of tests) was a reliable diagnosis of inadequate control. Endogenous ACTH concentrations did not differ between groups. The overlap of the cortisol/ACTH ratio between groups was large. Correct classification was only possible if the cortisol/ACTH ratio was >15, which occurred in 4% of tests. CONCLUSIONS AND CLINICAL IMPORTANCE: To monitor trilostane treatment the ACTH stimulation test cannot be replaced by baseline cortisol, ACTH concentration, or the cortisol/ACTH ratio.

Duration of t4 suppression in hyperthyroid cats treated once and twice daily with transdermal methimazole.

BACKGROUND: Transdermal methimazole is an acceptable alternative to oral treatment for hyperthyroid cats. There are, however, no studies evaluating the duration of T4 suppression after transdermal methimazole application. Such information would be valuable for therapeutic monitoring. OBJECTIVE: To assess variation in serum T4 concentration in hyperthyroid cats after once- and twice-daily transdermal methimazole administration. ANIMALS: Twenty client-owned cats with newly diagnosed hyperthyroidism. METHODS: Methimazole was formulated in a pluronic lecithin organogel-based vehicle and applied to the pinna of the inner ear at a starting dose of 2.5 mg/cat q12h (BID group, 10 cats) and 5 mg/cat q24h (SID group, 10 cats). One and 3 weeks after starting treatment, T4 concentrations were measured immediately before and every 2 hours after gel application over a period of up to 10 hours. RESULTS: Significantly decreased T4 concentrations were observed in week 1 and 3 compared with pretreatment concentrations in both groups. All cats showed sustained suppression of T4 concentration during the 10-hour period, and T4 concentrations immediately before the next methimazole treatment were not significantly different compared with any time point after application, either in the BID or SID groups. CONCLUSIONS: Because transdermal methimazole application led to prolonged T4 suppression in both the BID and SID groups, timing of blood sampling does not seem to be critical when assessing treatment response.

[Primary hyperaldosteronism in cats]. / Primärer Hyperaldosteronismus bei Katzen.

Primary hyperaldosteronism is a clinical syndrome characterized by an elevated aldosterone secretion by the adrenals. The present case series describes 7 cats with primary hyperaldosteronism, which were presented between 2002 and 2011. Common clinical symptoms were weakness, anorexia, cervical ventroflexion and blindness. All cats showed hypokalemia. In 6 cats, blood pressure was determined: 5 cats showed hypertension, of which 4 animals exhibited retinal detachment and blindness. In the ultrasonographic examination, unilateral adrenomegaly was present in 6 cats whereas one animal showed normal adrenals. In 4 cats, the serum aldosterone concentration was above the reference range. Five cats underwent unilateral adrenalectomy, which was accomplished uneventfully and returned the electrolytes back to normal. Histopathological examination of the adrenals revealed 2 carcinomas and 4 adenomas; one cat with ultrasonographic normal adrenals exhibited bilateral nodular hyperplasia.

Use of insulin glargine in dogs with diabetes mellitus.

The objective of this study was to evaluate the safety and efficacy of insulin glargine in dogs with diabetes mellitus (DM). Twelve client-owned dogs with DM were included. All dogs received insulin glargine every 12 hours for at least six months, re-evaluations were performed after one, two, four, eight, 12 and 24 weeks and included clinical signs, blood glucose curves (BGCs) and measurement of serum fructosamine concentrations. Mean blood glucose concentrations were significantly lower after two weeks of treatment and remained significantly lower for the duration of the study. By week 24, polyuria/polydipsia had improved in 91 per cent of the dogs. No clinical signs that could have been caused by hypoglycaemia were observed. Based on BGCs and remission of the clinical signs for judging the success of the treatment, 58, 33 and 8 per cent of the dogs attained good, moderate and poor glycaemic control by week 24 of the study, respectively. Insulin glargine administered subcutaneously twice daily is a possible and safe method of treatment for dogs with naturally occurring DM. Although only a few studies are available on the use of other types of insulin in dogs, their success rate is somewhat greater than that with insulin glargine.

Adrenocorticotropic hormone, but not trilostane, causes severe adrenal hemorrhage, vacuolization, and apoptosis in rats.

Adrenal necrosis has been reported as a complication of trilostane application in dogs with hyperadrenocorticism. One suspicion was that necrosis results from the increase of adrenocorticotropic hormone (ACTH) during trilostane therapy. The aim of the current study was to assess the effects of ACTH and trilostane on adrenal glands of rats. For experiment 1, 36 rats were divided into 6 groups. Groups 1.1 to 1.4 received ACTH in different doses (60, 40, 20, and 10 µg/d) infused subcutaneously with osmotic minipumps for 16 wk. Group 1.5 received saline, and group 1.6 received no therapy. For experiment 2, 24 rats were divided into 3 groups. Group 2.1 and 2.2 received 5 and 50 mg/kg trilostane/d orally mixed into chocolate pudding for 16 wk. Eight control rats received pudding alone. At the end of the experiments, adrenal glands were assessed for necrosis by histology and immunohistochemistry; levels of endogenous ACTH and nucleosomes were assessed in the blood. Rats treated with 60 µg ACTH/d showed more hemorrhage and vacuolization and increased numbers of apoptotic cells in the adrenal glands than rats treated with 20 or 10 µg ACTH/d, trilostane, or control rats. Rats treated with 60 µg ACTH/d had a higher amount of nucleosomes in the blood compared with rats treated with 10 µg ACTH/d, trilostane, or saline. We conclude that in healthy rats ACTH, but not trilostane, causes adrenal degeneration in a dose-dependent manner. Results of this study support the hypothesis that adrenal gland lesions seen in trilostane-treated dogs are caused by ACTH and not by trilostane.

Salivary cortisol concentrations in healthy dogs and dogs with hypercortisolism.

BACKGROUND: Measurement of salivary cortisol is a useful diagnostic test for hypercortisolism (HC) in humans. OBJECTIVES: To determine whether measurement of salivary cortisol concentration is a practical alternative to plasma cortisol to diagnose HC, to validate the use of salivary cortisol, and to examine the effect of time of day and sampling location on salivary cortisol. ANIMALS: Thirty healthy dogs and 6 dogs with HC. METHODS: Prospective, observational clinical trial including healthy volunteer dogs and dogs newly diagnosed with HC. Salivary and plasma cortisol concentrations were measured with an immunoassay analyzer. Intra- and interassay variability, linearity, and correlation between salivary and plasma cortisol concentrations were determined. RESULTS: The required 300 microL of saliva could not be obtained in 88/326 samples from healthy dogs and in 15/30 samples from dogs with HC. The intra-assay variability for measurement of salivary cortisol was 5-17.7%, the interassay variability 8.5 and 17.3%, and the observed to expected ratio 89-125%. The correlation (r) between salivary and plasma cortisol was 0.98. The time of day and location of collection did not affect salivary cortisol concentrations. Dogs with HC had significantly higher salivary cortisol values than healthy dogs (10.2 +/- 7.3 nmol/L versus 1.54 +/- 0.97 nmol/L; P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: The ROCHE Elecsys immunoassay analyzer correctly measured salivary cortisol in dogs. However, a broad clinical application of the method seems limited, because of the large sample volume required.

10-day hyperlipidemic clamp in cats: effects on insulin sensitivity, inflammation, and glucose metabolism-related genes.

Obesity and hyperlipidemia are associated with impaired insulin sensitivity in human type 2 diabetes mellitus, possibly due to activation of a mild inflammatory response. Because obesity-induced insulin resistance predisposes cats to diabetes and because hyperlipidemia is a frequent concurrent finding, excess lipids may also impair insulin sensitivity in cats. Healthy cats (n=6) were infused with lipids (Lipovenoes 10%) for 10 days to clamp blood triglycerides at the approximate concentration of untreated feline diabetes (3-7 mmol/l). Controls received saline (n=5). On day 10, plasma adiponectin and proinflammatory markers were measured. Whole-body insulin sensitivity was calculated following an intravenous glucose tolerance test. Tissue mRNAs of glucose metabolism-related genes were quantified in subcutaneous and visceral fat, liver, and skeletal muscles. Accumulation of lipids was assessed in liver. At the termination of infusion, whole-body insulin sensitivity did not differ between groups. Compared to saline, cats infused with lipids had 50% higher plasma adiponectin and 2-3 times higher alpha(1)-acid glycoprotein and monocyte chemoattractant protein-1. Unexpectedly, lipid-infused cats had increased glucose transporter-4 (GLUT4) mRNA in the visceral fat, and increased peroxisome proliferative activated receptor-gamma2 (PPARgamma2) in subcutaneous fat; adiponectin expression was not affected in any tissue. Lipid-infused cats developed hepatic steatosis. Although hyperlipidemia induced systemic inflammation, whole-body insulin sensitivity was not impaired after 10 day infusion. Increased circulating adiponectin may have contributed to prevent insulin resistance, possibly by increasing GLUT4 and PPARgamma2 transcripts in fat depots.

Comparison of 2 doses of recombinant human thyrotropin for thyroid function testing in healthy and suspected hypothyroid dogs.

BACKGROUND: Various protocols using different doses of recombinant human thyrotropin (rhTSH) in TSH stimulation testing have been described. However, the influence of TSH dosage on thyroxine (T4) concentration has not yet been evaluated in suspected hypothyroid dogs. OBJECTIVE: To evaluate the effectiveness of 2 doses of rhTSH. ANIMALS: Fifteen dogs with clinical signs consistent with hypothyroidism and abnormal stimulation results with 75 microg rhTSH and 18 clinically healthy dogs. METHODS: All dogs were stimulated with 75 and 150 microg rhTSH IV in a 1st and 2nd stimulation test, respectively. Blood samples were taken before and 6 hours after rhTSH administration for determination of total T4 concentration. RESULTS: Using the higher dose led to a normal test interpretation in 9 of the 15 dogs, in which stimulation had been abnormal using the lower dose. Based on follow-up information, hypothyroidism was excluded in 7 of these 9 dogs. In all 6 dogs with a blunted response to the higher dose, hypothyroidism could be confirmed. Healthy dogs showed significantly higher post-TSH T4 concentrations with the higher compared with the lower dose. Post-TSH T4 concentrations after TSH stimulation were not related to dogs' body weight in either healthy or diseased dogs. CONCLUSIONS AND CLINICAL RELEVANCE: TSH dose significantly influenced test interpretation in suspected hypothyroid dogs. Differentiation between primary hypothyroidism and nonthyroidal disease was improved with 150 microg rhTSH. Because this effect was independent of the dogs' body weight, the higher dose is recommended in dogs that have concurrent disease or are receiving medication.

Remission of diabetes mellitus in cats with diabetic ketoacidosis.

BACKGROUND: Diabetic ketoacidosis (DKA) has long been considered a key clinical feature of type-1 diabetes mellitus (DM) in humans although. An increasing number of cases of ketoacidosis have been reported in people with type-2 DM. HYPOTHESIS/OBJECTIVES: Cats initially diagnosed with DKA can achieve remission from diabetes. Cats with DKA and diabetic remission are more likely to have been administered glucocorticoids before diagnosis. ANIMALS: Twelve cats with DKA and 7 cats with uncomplicated DM. METHODS: Retrospective case review. Medical records of cats presenting with DKA or DM were evaluated. Diabetic remission was defined as being clinically unremarkable for at least 1 month after insulin withdrawal. The cats were assigned to 1 of 3 groups: (1) cats with DKA and diabetic remission; (2) cats with DKA without diabetic remission; and (3) cats with DM and diabetic remission. RESULTS: Seven cats with DKA had remission from diabetes. These cats had significantly higher concentrations of leukocytes and segmented neutrophils, and significantly lower concentrations of eosinophils in blood and had pancreatic disease more often than did cats with uncomplicated DM and diabetic remission. With regard to pretreatment, 3/7 cats in group 1, 1/5 cats in group 2, and 1/7 cats in group 3 had been treated with glucocorticoids. CONCLUSIONS AND CLINICAL IMPORTANCE: Remission of DM in cats presenting with DKA is possible. Cats with DKA and remission have more components of a stress leucogram, pancreatic disease, and seemed to be treated more often with glucocorticoids than cats with uncomplicated DM and diabetic remission.

Serum concentrations of cortisol and cortisone in healthy dogs and dogs with pituitary-dependent hyperadrenocorticism treated with trilostane.

The serum concentrations of cortisol and cortisone were measured in 19 healthy dogs and in 13 dogs with pituitary-dependent hyperadrenocorticism (PDH) before and one hour after an injection of synthetic adrenocorticotropic hormone (ACTH). In the dogs with pdh, the cortisol and cortisone concentrations were measured before and after one to two weeks and three to seven weeks of treatment with trilostane. The dogs with PDH had significantly higher baseline and poststimulation concentrations of cortisol and cortisone, and higher baseline cortisol:cortisone ratios than the healthy dogs. During the treatment with trilostane, the poststimulation cortisol, the baseline and poststimulation cortisone concentrations, and the baseline and poststimulation cortisol:cortisone ratios decreased significantly. The decrease in poststimulation cortisone was significantly smaller than the decrease in cortisol.

Evaluation of cortisol precursors for the diagnosis of pituitary-dependent hypercortisolism in dogs.

The serum concentrations of cortisol, 17alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone, 21-deoxycortisol and 11-deoxycortisol were measured in 19 healthy dogs, 15 dogs with pituitary-dependent hypercortisolism (pdh) and eight dogs with other diseases before and one hour after an injection of synthetic adrenocorticotrophic hormone (acth). At both times the dogs with pdh had significantly higher concentrations of cortisol, 17alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone and 21-deoxycortisol than the healthy dogs. Basal 11-deoxycortisol concentrations were also significantly higher in dogs with pdh compared with healthy dogs. When compared with the dogs with other diseases, the dogs with pdh had significantly higher basal and post-acth cortisol and basal 21-deoxycortisol, and significantly lower post-acth 11-deoxycortisol concentrations. The dogs with other diseases had significantly higher post-acth cortisol, 17alpha-hydroxyprogesterone and 11-deoxycortisol concentrations than the healthy dogs. In general, the post-acth concentrations of 17alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone, 11-deoxycortisol and 21-deoxycortisol were more variable than the post-acth concentrations of cortisol, resulting in large overlaps of the concentrations of these hormones between the three groups. A two-graph receiver operating characteristic (ROC) analysis was used to maximise the sensitivity and specificity of each hormone for diagnosing hypercortisolism; it showed that the post-acth concentration of cortisol had the highest sensitivity and specificity. The overlaps between the healthy dogs, the dogs with pdh and the dogs with other diseases suggested that the individual precursor hormones would not be useful as a screening test for hypercortisolism.