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.

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.

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 IV 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.

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.

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.

Heimmonitoring des Blutglukosespiegels durch Besitzer diabetischer Hunde und Katzen

Generation of blood glucose curves is essential to monitor glycemic control in dogs and cats with diabetes mellitus. Up till now blood collection and blood glucose measurements could only be performed in a hospital. However, glucose concentrations measured in a hospital environment can markedly differ from concentrations measured at home, due to reduced appetite, different activity level and stressful handling. At the Clinic of Small Animal Internal Medicine, University of Zurich, a new method to collect capillary blood from the ear and to measure blood glucose by means of a portable glucose meter has been developed. This method enables owners of diabetic dogs or cats to determine blood glucose concentrations and generate blood glucose curves at home. Three cases demonstrate, how much blood glucose concentrations at home may differ from those in the hospital and how home monitoring can help to establish diabetic control in dogs and cats.

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.

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.

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.

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.

Quantitative real-time PCR for the measurement of 11beta-HSD1 and 11beta-HSD2 mRNA levels in tissues of healthy dogs

The 11beta-hydroxysteroid dehydrogenase (11beta-HSD) exists in two isoforms, 11beta-HSD1 and 11beta-HSD2. 11beta-HSD1 generates active cortisol from cortisone and appears to be involved in insulin resistant states. 11beta-HSD2 protects the mineralocorticoid receptor from inappropriate activation by glucocorticoids and is important to prevent sodium retention and hypertension. The purposes of the present study were to develop two real-time PCR assays to assess 11beta-HSD1 and 11beta-HSD2 mRNA expression and to evaluate the tissue distribution of the two isoforms in dogs. Thirteen different tissues of 10 healthy dogs were evaluated. Both real-time PCR assays were highly specific, sensitive and reproducible. Highest 11beta-HSD1 mRNA expression was seen in liver, lung, and renal medulla; highest 11beta-HSD2 mRNA expression in renal cortex, adrenal gland, and renal medulla. Higher 11beta-HSD1 than 11beta-HSD2 mRNA levels were found in all tissues except adrenal gland, colon, and rectum. Our results demonstrate that the basic tissue distribution of 11beta-HSD1 and 11beta-HSD2 in dogs corresponds to that in humans and rodents. In a next step 11beta-HSD1 and 11beta-HSD2 expression should be assessed in diseases like obesity, hypercortisolism, and hypertension to improve our knowledge about 11beta-HSD activity, to evaluate the dog as a model for humans and to potentially find new therapeutic options.

Cortisol, aldosterone, cortisol precursor, androgen and endogenous ACTH concentrations in dogs with pituitary-dependant hyperadrenocorticism treated with trilostane

Trilostane is thought to be a competitive inhibitor of the 3beta-hydroxysteroid dehydrogenase (3beta-HSD), an essential enzyme system for the synthesis of cortisol, aldosterone and androstenedione. Due to its reliable clinical efficacy, trilostane is increasingly used to treat dogs with pituitary-dependant hyperadrenocorticism (PDH). The objective of our study was to investigate the effect of trilostane on precursor concentrations located before (17alpha-OH-pregnenolone, dehydroepiandrostenedione) and after (17alpha-OH-progesterone, androstenedione, 11-deoxycortisol, 21-deoxycortisol) the proposed enzyme inhibition, on end products of steroid biosynthesis (cortisol and aldosterone) and on endogenous adrenocorticotrophic hormone (ACTH) concentrations in dogs with PDH. Hormones of the steroid biosynthesis pathway were evaluated in 15 dogs before and 1h after injection of synthetic ACTH prior to (t(0)), in weeks 1-2 (t(1)) and in weeks 3-7 (t(2)) of trilostane treatment. Endogenous ACTH concentrations were measured at the same time points before performing the ACTH stimulation test. During trilostane treatment baseline and post-stimulation cortisol concentrations decreased significantly. Baseline serum aldosterone levels showed a significant increase; post-stimulation values decreased. Baseline and post-stimulation 17alpha-OH-pregnenolone and dehydroepiandrostenedione concentrations increased significantly. 17alpha-OH-progesterone and androstenedione levels did not change. Post-stimulation 21-deoxycortisol concentrations decreased significantly, baseline 11-deoxycortisol concentrations increased significantly. Endogenous ACTH levels showed a significant increase. The significant increase in 17alpha-OH-pregnenolone and dehydroepiandrostenedione concentrations confirms an inhibitory effect of trilostane on the 3beta-HSD. Since 17alpha-OH-progesterone concentrations did not change, but cortisol concentrations markedly decreased, trilostane seems to influence additional enzymes of the hormone cascade, like the 11beta-hydroxylase and possibly the 11beta-hydroxysteroid dehydrogenase.