Diagnosis of spontaneous canine hyperadrenocorticism: 2012 ACVIM consensus statement (small animal)

Cytologic Evaluation as a Diagnostic Tool to Differentiate Adrenocortical Tumors and Pheochromocytomas

BACKGROUND

The utility of cytologic evaluation to distinguish adrenocortical tumors and pheochromocytomas in dogs has not been thoroughly investigated, partly because of the perceived risks of the procedure.

OBJECTIVES

Report test characteristics of fine needle aspiration (FNA) and cytologic evaluation for differentiation of adrenocortical tumors and pheochromocytomas in dogs. Complications associated with FNA also were recorded.

ANIMALS

Thirty-eight dogs with 40 adrenal tumors that had FNA and cytologic evaluation performed before adrenalectomy were included in the study from three institutions. Tumors included 17 pheochromocytomas, 21 adrenocortical tumors, 1 concurrent adrenocortical adenoma and pheochromocytoma, and 1 malignant neoplasm.

RESULTS

Of the 40 FNA cytologic aspirations performed, 35 (87.5%) had a predominant cell type identified and therefore were considered of diagnostic quality. Of these, 30 (85.7%) correlated with the final histopathological diagnosis. When all samples were included, FNA and cytologic evaluation had a sensitivity of 77.3%, specificity of 76.5%, positive predictive value of 81.0%, negative predictive value of 72.2%, and accuracy of 76.9% for identifying adrenocortical tumors. For pheochromocytomas, these values were 72.2%, 95.2%, 92.8%, 80.0%, and 84.5%, respectively. Six (15.9%) dogs had self-limiting complications associated with the FNA procedure.

CONCLUSION AND CLINICAL IMPORTANCE

Fine needle aspiration and cytologic evaluation of adrenal tumors has a low complication rate and can help differentiate adrenocortical tumors and pheochromocytomas. Thus, cytologic evaluation of adrenal tumors should be considered to help differentiate adrenal tumors and allow more individualized treatment of affected dogs.

Patient signalment and aetiology of hypercortisolism in Australian dogs with Cushing's syndrome

OBJECTIVE

Patient characteristics of Cushing's syndrome differ between countries and have not been assessed in the Australian dog population. This study describes signalment and distribution of adrenocorticotropic hormone (ACTH)-dependent hypercortisolism (ADH) and ACTH-independent hypercortisolism (AIH) in Australian dogs.

ANIMALS

Two-hundred client-owned dogs that had endogenous ACTH concentrations measured by radioimmunoassay.

METHODS

Animals with Cushing's syndrome were identified from laboratory accessions and signalment details recorded. Dogs were classified as having ADH or AIH based on their endogenous ACTH concentration and, if equivocal, by additional data obtained from medical records.

RESULTS

Dogs had a median age of 11 years (range 3.5-18) and median body weight of 8.6 kg (2.5-50.8) with 67% of dogs weighing <10 kg and 83% <20 kg. The majority were female (62%) and neutered (91%). Maltese dogs comprised 19% of the study population and were over-represented relative to the general dog population. Dogs of this breed were diagnosed at an earlier age than other breeds and crosses. One hundred and eighty seven of 200 dogs (93.5%; 95% confidence interval [CI]: 89.1-96.4) were diagnosed with ADH and 5 dogs (2.5%; 95% CI: 0-0.05) with AIH; an aetiology could not be established for the remaining dogs.

CONCLUSIONS

Australian dogs with Cushing's syndrome were mostly small breed dogs and almost exclusively had ADH. Maltese dogs were frequently affected and developed the disease earlier in life compared with other breeds. These data can facilitate identification of Australian dogs at risk for the disease and assist in diagnostic and therapeutic decision-making.

Multiple pathological bone fractures in a dog with adrenal-dependent Cushing's syndrome

Pathological bone fractures may occur secondarily to Cushing's syndrome in people. Although low bone mineral density due to cortisol excess has been described in dogs, there is no evidence that dogs with Cushing's disease can develop osteoporosis or secondary bone fractures. Here, we report a case of a dog with Cushing's disease and multiple pathological bone fractures. A 14-year-old female spayed mixed-breed dog was attended due to progressive lethargy, weakness, difficulty moving, trembling and clinical signs of Cushing's syndrome (polyuria, polydipsia, alopecia and abdominal distension). After confirmation of the diagnosis of Cushing's disease and 2 days after starting trilostane treatment (0.27 mg/kg every 12 hours), the dog presented to our hospital with reluctance to rise. In the computed tomography scan, decreased bone density in cervical and thoracic vertebrae, ribs scapular bones and multiple rib fractures were detected. Despite 8 days of hospitalisation, reluctance to rise and walk persisted. Given the unfavourable progression of the diseases, the owner opted for euthanasia. Post mortem evaluation confirmed a cortical carcinoma of the left adrenal gland and thin, irregular spicules and trabeculae of compact bone and reduced thickness of the cortex of the ribs.

Diagnosis of naturally-occurring Cushing's syndrome by primary care veterinarians in selected European countries

BACKGROUND

Several tests are available to diagnose naturally-occurring Cushing's syndrome in dogs but there is a paucity of information on how primary care veterinarians (PCVs) use or interpret them.

OBJECTIVES

Determine how PCVs from selected European countries diagnose Cushing's syndrome in dogs.

METHODS

Cross-sectional survey study assessing testing protocols used by PCVs for screening and differentiation of Cushing's syndrome.

RESULTS

Two thousand one hundred and seventy-eight responses from 9 European countries were included. When Cushing's syndrome was suspected, 98.7% of respondents perform endocrine testing, whereas 1.2% rely on a treatment trial. Among the former, 59.9% reported performing screening tests in the absence of supportive clinical signs but with consistent clinicopathological abnormalities. Of 2150 respondents who performed endocrine testing, 66.6% report always using the same initial screening tests regardless of their pretest suspicion of disease. The tests most reported are the ACTH stimulation test (34.8%), low-dose dexamethasone suppression test (LDDST; 30.4%) or a combination of different tests (25.2%). In the absence of financial constraint, 1419 (66.0%) respondents always attempted differentiation, using abdominal ultrasonography (81.0%) and LDDST (46.1%). Overall, 69.8% of respondents reported offering referral to a specialist in ≤20% of cases suspected or diagnosed with Cushing's syndrome over the previous 5 years.

CONCLUSIONS AND CLINICAL IMPORTANCE

Testing protocols vary among PCVs. Almost 60% of respondents potentially screen dogs without consistent clinical signs, raising concerns for overdiagnosis. A proportion never attempt differentiation, which likely affects prognosis. Cases are rarely referred to a specialist, reflecting that Cushing's syndrome is mainly managed in primary care practices. These results suggest that there is room for further education of PCVs.

Clinical findings, treatment, and outcomes in cats with naturally occurring hypoadrenocorticism: 41 cases

BACKGROUND

Hypoadrenocorticism in cats is uncommonly reported. Most reports consist of cats with hyponatremia, hyperkalemia, or both.

HYPOTHESIS/OBJECTIVES

To describe clinical findings, treatment response, and outcome in cats diagnosed with hypoadrenocorticism, including cats with abnormal and normal serum sodium and potassium concentrations.

ANIMALS

Forty-one cats with hypoadrenocorticism; 36 with and 5 without abnormal serum sodium and potassium concentrations.

METHODS

Multicenter retrospective observational study. Data for the entire cohort were assessed using descriptive statistics and differences between cats with and without abnormal serum sodium and potassium concentrations were evaluated.

RESULTS

Median age was 5.7 years (range, 0.2-13.8). Twenty-three (56%) cats were male and 18 (44%) were female. Cats with hyponatremia, hyperkalemia, or both were less likely to have a history of vomiting (P = .01) but more likely to be hypothermic (P = .03), dehydrated (P = .04) or weak (P = .04) on examination, compared with nonhyponatremic and nonhyperkalemic cats. Frequency of hypercalcemia was 31.7%. Exocrine pancreatic insufficiency (EPI) was diagnosed in 4/7 cats tested; all 4 had concurrent cobalamin deficiency. Thirty-five (85.4%) cats survived to discharge. In 2 cats, hypoadrenocorticism occurred secondary to lymphoma. Median survival time (MST) for all-cause mortality was 2035 days (95% confidence interval [CI], 294-4380 days); MST for disease-specific mortality was not reached.

CONCLUSIONS AND CLINICAL IMPORTANCE

Approximately one-third of cats with hypoadrenocorticism had hypercalcemia. In some cases, hyponatremia and hyperkalemia were not observed. Cats with nonneoplastic associated hypoadrenocorticism that survive initial hospitalization can have a favorable long-term prognosis. Testing for EPI may be warranted in cats with hypoadrenocorticism.

Ultrasonographic adrenal gland changes in dogs with Cushing's syndrome with a low-dose dexamethasone suppression test result consistent with partial suppression or escape pattern

Background

Cushing's syndrome (CS) in dogs is mainly caused by pituitary-dependent (PDH) or adrenal-dependent (ADH) hypercortisolism. Result of the low-dose-dexamethasone suppression test (LDDST) with partial suppression (PSP) or escape pattern (EP) are indicative of PDH. No data concerning the ultrasonographic characteristics of the adrenal glands from dogs with these patterns exists.

Objective

To describe ultrasonographic appearance of adrenal glands in dogs with CS, with a LDDS test result consistent with PSP or EP.

Animals

Forty-nine client owned dogs with a diagnosis CS with a PSP or EP in the LDDST.

Methods

Retrospective evaluation of ultrasonographic adrenal gland size, shape and echogenicity. The dorsoventral thickness ratio (DVTR) and dorsoventral thickness difference ratio (DVTDR) was calculated.

Results

PSP and EP occurred in 42.9 and 57.1% of all LDDST. The median maximum width of the left adrenal gland was 0.71 cm (IQR, 0.24 cm) and of the right 0.75 cm (IQR, 0.19 cm) in all dogs and there was no difference between both patterns. There was a significant correlation between adrenal gland width and weight (left adrenal gland p = 0.002, right adrenal gland p = 0.017). In 9/49 dogs (18.4%), an adrenal asymmetry with a DVTDR >0.3 was present. In 7 of these 9 dogs, follow-up was available indicating presence of PDH.

Conclusions and clinical importance

Based on follow up, PSP and EP of the LDDST were very supportive of PDH. Bilaterally symmetric adrenomegaly is a characteristic finding in dogs with PDH, however the size of adrenal gland width in this cohort was smaller than previously reported. Adrenal asymmetry was noted in approximately 20%.

Immunohistochemical expression of CYP11A1, CYP11B, CYP17, and HSD3B2 in functional and nonfunctional canine adrenocortical tumors

BACKGROUND

Functionality of human adrenal tumors is inferred by CYP11B1 (cortisol synthase) expression, CYP11B2 (aldosterone synthase) expression, or both.

HYPOTHESIS/OBJECTIVES

Nonfunctional canine adrenal tumors have low expression of steroidogenic enzymes, whereas aldosterone-producing tumors express CYP11B, and cortisol-producing tumors express both CYP11B and CYP17.

ANIMALS

Twenty-two client-owned dogs with adrenocortical tumors (ACT) (8 nonfunctional, 7-cortisol producing, 2 aldosterone-producing and 5 functional noncortisol producing) and 2 dogs with normal adrenal glands.

METHODS

Retrospective case series. Adrenal functionality was determined from clinical signs and endocrine testing. CYP11A1, CYP11B, CYP17, and HSD3B2 expression was detected by immunohistochemistry on formalin-fixed paraffin-embedded adrenal tissue. Protein expression was semiquantified by 2 blinded observers using H-scoring (results reported as median [range]) and compared in nonfunctional and cortisol-producing adrenal tumors by Mann-Whitney U tests.

RESULTS

CYP11A1, CYP11B, and HSD3B2 were present within all cortical layers of normal adrenal glands, and CYP17 was expressed within the zona fasciculata and zona reticularis. Expression of CYP11A1 (191.25 [97.5-270] vs. 175 [102.5-295] P = .69), CYP11B (190 [130-265] vs. 147.5 [95-202.5]; P = .07), CYP17 (177.5 [87.5-240] vs. 247.5 [55-292.5]; P = .40), and HSD3B2 (230 [47.5-295] vs. 277.5 [67.5-295]; P = .34) were not significantly different between cortisol-producing and nonfunctional ACT.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our findings suggest it is not possible to determine functionality of canine ACT by immunohistochemistry for steroidogenic enzymes. Tumor size cannot be used to infer functionality of adrenal tumors.

Cushing's Myopathy in Dogs: Prevalence, Clinical Abnormalities, and Response to Treatment

A distinct myotonia is a muscle disorder that may occur secondary to excess corticosteroids (hyperadrenocorticism, HAC, or Cushing's disease) and is associated with electrodiagnostic abnormalities on electromyography (EMG). Clinically these disorders cause muscle stiffness, weakness, atrophy, and/or contractures, which can severely limit the quality of life of those affected. To date, there are very few published data regarding the onset, development, and treatment of hyperadrenocorticism-associated myotonia/pseudomyotonia. This is a multi-institutional retrospective study describing the clinical signs, diagnosis, and treatment of HAC-associated myotonia/pseudomyotonia. We found that this disorder was and continues to be rare. It most commonly occurs in adult dogs with chronic steroid exposure secondary to pituitary-dependent HAC. No cases of adrenal dependent HAC were identified in this population. In addition to muscle stiffness, dermatologic disease and liver enzyme abnormalities were common. A wide variety of therapeutic strategies, including polypharmacy and physical rehabilitation, were implemented, with little success. Analgesics were the most frequently administered type of medication.

Altered Gut Microbiome Composition in Dogs with Hyperadrenocorticism: Key Bacterial Genera Analysis

Hyperadrenocorticism (HAC) is a common endocrine disorder in dogs, which is associated with diverse metabolic abnormalities. We hypothesized that elevated cortisol levels in dogs with HAC disrupt the gut microbiome (GM), and this disruption persists even after trilostane treatment. This study explored GM composition in dogs with HAC. We included 24 dogs, 15 with HAC and 9 healthy controls, and followed up with 5 dogs with HAC who received trilostane treatment. The GM analysis revealed significant compositional changes in dogs with HAC, including reduced microbiome diversity compared to healthy controls, particularly in rare taxa, as indicated by the Shannon index (p = 0.0148). Beta diversity analysis further showed a distinct clustering of microbiomes in dogs with HAC, separating them from healthy dogs (p < 0.003). Specifically, an overrepresentation of Proteobacteria (Pseudomonadota), Actinobacteria, Bacteroides, Enterococcus, Corynebacterium, Escherichia, and Proteus populations occurred alongside a decreased Firmicutes (Bacillota) population. Despite trilostane treatment, gut dysbiosis persisted in dogs with HAC at a median of 41 d post treatment, suggesting its potential role in ongoing metabolic issues. We identified GM dysbiosis in dogs with HAC by examining key bacterial genera, offering insights into potential interventions like probiotics or fecal microbiota transplants for better HAC management.

Association between post-ACTH cortisol and trilostane dosage in dogs with pituitary-dependent hypercortisolism

Trilostane is the current treatment of choice for managing pituitary-dependent hypercortisolism (PDH) in dogs. While prescribing higher initial doses may elevate the risk of iatrogenic hypocortisolism, opting for more conservative approach could result in delayed disease control, since most individuals end up requiring dosage increases. The adrenocorticotrophin stimulation test (ACTHst), a widely recognized hormonal test for assessing adrenal function, is an essential tool for monitoring the pharmacological treatment of canine hypercortisolism (CH) that can also be used for diagnostic purposes. The aim of this study was to investigate the relationship between post-ACTH cortisol (cpACTH) at PDH diagnosis and the required trilostane dose for sign control and endogenous cortisol regulation in dogs, considering a hypothesis that higher serum cpACTH concentration would necessitate a higher trilostane dosage for disease management. Data for 43 dogs with PDH had their diagnostic cpACTH recorded and correlated to the trilostane dosage necessary to control clinical signs and achieve satisfactory cortisol levels (ideally 2-7 μg/dL). The odds ratio (p=0.042) suggests that dogs with cpACTH ≥ 27 μg/dL at diagnosis are 96% more likely to need a higher trilostane dosage for achieving satisfactory control of PDH. Thus, cpACTH was found to be associated with the final trilostane dose for controlling PDH in dogs.

Urinary steroid profiling using liquid chromatography-tandem mass spectrometry for the diagnosis of canine Cushing's syndrome

Serum cortisol measurements by chemiluminescence enzyme immunoassay (CLEIA) are widely used to diagnose hypercortisolism (HC) or Cushing's syndrome in dogs. However, they are associated with problems such as the need for multiple blood collections under stressful conditions or cross-reactivity between hormones. Therefore, a less invasive and more accurate diagnostic method is required. This study aimed to develop a urinary steroid profile analysis method using liquid chromatography-tandem mass spectrometry (LC/MS/MS) and to evaluate its clinical usefulness. Sixty-five healthy dogs and 38 dogs with suspected HC were included in the study. Using LC/MS/MS, the levels of 11 steroid hormones in the urine were determined. We established the upper limit of the reference interval for each urinary steroid-to-creatinine ratio and evaluated their diagnostic performances. The levels of the five steroid hormones were significantly higher in the 14 dogs with HC than in the 24 dogs with mimicking HC and 65 healthy dogs. The urinary corticosterone-to-creatinine ratio showed the highest diagnostic accuracy (area under the curve, 0.96). A significant correlation was seen between urinary cortisol concentrations measured by LC/MS/MS and CLEIA (rs = 0.88, P <0.001), although the CLEIA measurements were significantly higher than the LC/MS/MS measurements (P <0.001). LC/MS/MS-based urinary steroid profiles are a promising tool for diagnosing canine HC.

Can neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios be used as markers for hypercortisolism in dogs?

Changes in neutrophil-to-lymphocite ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been identified in dogs with hypercortisolism (HC), but, no studies have investigated the changes in these inflammatory biomarkers as cost-effective and available parameters for the diagnosis and management of HC. This study was performed to evaluate whether NLR and PLR could be used as biomarkers for the diagnosis and treatment response in dogs with HC. This retrospective study included 67 dogs with HC, 58 dogs with non-adrenal illness (NAI), and 39 healthy dogs. NLR and PLR were compared among the three groups. Cut-off values of NLR and PLR for HC screening and percent change in biomarkers for assessing treatment response were evaluated. In addition, the NLR and PLR were compared before and after trilostane treatment. NLR and PLR were significantly higher in the HC group than in the NAI and healthy groups. The NLR cut-off value of 4.227 had a sensitivity of 67.16% and specificity of 65.52%, and the PLR cut-off value of 285.0 had a sensitivity of 56.72% and specificity of 70.69% for differentiating between dogs with HC and those with NAI, respectively. Furthermore, a significant decline in NLR was observed after treatment in the well-controlled HC group. The cutoff value of percent change in NLR to identify well-controlled HC was -7.570%; sensitivity and specificity were 100% and 63.64%, respectively. Therefore, NLR and PLR might be used cautiously as supportive biomarkers for HC diagnosis, and NLR could be a potential monitoring tool in assessing the treatment response of HC in dogs.

Ultrasonographic measurements of the normal adrenal glands in guinea pigs (Cavia Porcellus)

Hyperadrenocorticism is an uncommon but important endocrine disease in guinea pigs, but due to its subtle clinical signs and the limited information in veterinary literature, it can be underdiagnosed or misdiagnosed. Ultrasound of the adrenal glands in patients with suspected hyperadrenocorticism can help in identifying adrenomegaly. The purpose of this prospective study was to identify ultrasonographic adrenal gland dimensions in presumed healthy guinea pigs using the same standardized method described for dogs and cats. A conscious ultrasound scan was conducted on twenty client-owned, presumed healthy guinea pigs, and their adrenal glands were measured. A possible correlation between adrenal dimensions with age, sex, and body weight was investigated. The mean length, cranial and caudal pole thickness for the left and right adrenal glands were, respectively, 12.64 ± 2.11 mm and 11.55 ± 1.52 mm; 4.83 mm ± 1.03 mm and 4.69 ± 1.34 mm; 4.8 ± 1.23 mm and 4.04 ± 0.75 mm. The thickness of the left caudal pole was significantly higher than the right (P = 0.02). A significant positive correlation was found between the length of the left adrenal gland and both age (r = 0.46; P = .03) and weight (r = 0.59; P = .01). Statistical correlation between the thickness of each cranial and caudal pole, with age, sex, or weight, was not found. The dimensions provided could prove a useful tool in the clinical evaluation of guinea pigs with suspected hyperadrenocorticism.

Evaluation of coagulation profile in dogs with ACTH-dependent hyperadrenocorticism compared to healthy dogs by rotational thromboelastometry (ROTEM)

Despite their low morbidity, thromboembolic events in hyperadrenocorticism are associated with high mortality. Identifying the main hemostatic abnormalities will improve the prophylactic approach of these canine patients. The aim of this study was to evaluate hemostatic alterations related with ACTH-dependent HAC and its association with hypercoagulable state. For this purpose, 25 dogs diagnosed with ACTH-dependent HAC were compared with 28 healthy dogs as a control group. The hemostatic variables included platelet count, antithrombin, fibrinogen, D-dimer, PT, aPTT, rotational thromboelastometry (ROTEM) and platelet aggregation. Results showed a hypercoagulable state in 32% (8/25) dogs by ROTEM, which had at least 2 of the next features: decreased coagulation time (CT) or clot formation time (CFT) on INTEM (5/25) or EXTEM (4/25); increased maximum clot firmness (MCF) on INTEM (9/25), EXTEM (6/25) and FIBTEM (9/25). These same variables had a significant difference (P≤ 0.05) compared with the control group, as well as the parameters of α-angle and CT. Median fibrinogen levels (310 vs.178 mg/dL), mean platelet aggregation (11.1 vs. 7.9 Ohms), median platelet count (360 vs. 225 ×103/µL) and mean antithrombin activity (140 vs. 119%) were increased in ACTH-dependent HAC dogs compared to control group. PT (7.1 vs. 8.0 seconds) and aPTT (11.6 vs. 15.2 seconds) were also shortened in ACTH-dependent HAC dogs. Our findings confirm the presence of a hypercoagulable tendency in dogs with HAC. Although multifactorial, fibrinogen concentration and MCF FIBTEM showed the relevance of this protein for hypercoagulability in HAC.

Phosphocalcic metabolism and its potential association with biomarkers of kidney disease in dogs with spontaneous hyperadrenocorticism

The pathogenesis of increased serum phosphate concentration and proteinuria in dogs with spontaneous hyperadrenocorticism (HAC) is unclear. A potential link between proteinuria and calcium/phosphate metabolism has never been studied in dogs with HAC. The aims of the study were: (1) To evaluate calcium/phosphate metabolism in dogs with spontaneous HAC and compare to healthy dogs as well as to dogs with non-HAC illness; (2) to look for associations between markers of calcium/phosphate metabolism and biomarkers of kidney disease in dogs with HAC. Fifty-four dogs were included in the study, classified as HAC (n=27), non-HAC disease (n=17), and healthy (n=10). Serum calcium, phosphate, 25(OH)Vitamin D, 1,25(OH)2Vitamin D, plasma intact parathyroid hormone concentration (iPTH), FGF23, and urinary fractional excretion of calcium and phosphate were evaluated in all dogs at diagnosis and compared between each group. The correlation between these variables and urine protein-to-creatinine ratio (UPC) and urinary N-acetylglucosaminidase-to-creatinine ratio (uNAG/C) was evaluated in the HAC group. Medians [range] of serum phosphate concentration, urinary fractional excretion of calcium (FE(Ca)), and iPTH were significantly higher in dogs with HAC than in dogs with non-HAC illness (P<0.01) and healthy dogs (P<0.01). Increased 1,25(OH)2Vitamin D/25(OH)Vitamin D was also observed (P<0.001). In HAC group, UPC was significantly negatively correlated with 25(OH)Vitamin D (r(s): -0.54; P<0.01). Urinary NAG/C was significantly positively correlated with serum phosphate (r(s): 0.46; P=0.019). Increased serum phosphate, urinary excretion of calcium, and hyperparathyroidism were observed in dogs with HAC. Vitamin D metabolism may be shifted towards increased 1-alpha hydroxylation.

Description of serum symmetric dimethylarginine concentration and of urinary SDS-AGE pattern in dogs with ACTH dependent hyperadrenocorticism

Serum symmetric dimethylarginine (SDMA) and patterns of urinary protein separated by sodium dodecyl sulfate agarose gel electrophoresis (SDS-AGE) have not been investigated as biomarkers in dogs with ACTH-dependent hyperadrenocorticism (ADHAC). This exploratory prospective study aimed to evaluate SDMA, serum creatinine (sCR), and SDS-AGE in dogs with ADHAC with and without proteinuria (ADHAC-P and ADHAC-nP, respectively). Thirty-five pet dogs classified as ADHAC-P (n=16), ADHAC-nP (n=6) and healthy (n=13) were included. Renal biomarkers were evaluated in all dogs at diagnosis. Baseline concentration of SDMA was not significantly different between the three groups (P = 0.15) whereas sCr was significantly lower in dogs in ADHAC dogs compared to healthy dogs (88.0 µmol/L [70.4-132.6; 79.2-114.4]) whether they had proteinuria or not (P = 0.014 and 0.002, respectively). However, baseline concentrations of sCr and SDMA were not significantly different between dogs with ADHAC-P dogs (SDMA, 8 µg/dL [5-12; 7-9]; sCr, 57.2 µmol/L [35.2-212.2; 52.8-92.4]) and ADHAC-nP dogs (SDMA, 8.5 µg/dL [7-13; 8-10]; sCr, 70.4 µmol/L [61.6-79.2; 61.6-70.4]) (P = 0.35 and P = 0.41, respectively). Proteinuria in dogs with ADHAC-P was mainly of glomerular origin (SDS-AGE pattern: glomerular in 10/16 dogs; mixed glomerular/tubular in four dogs). In our study, SDMA was neither significantly different in dogs with ADHAC whether they were proteinuric or not, nor between ADHAC and healthy dogs. Urinary electrophoresis provides additional information to the UPC and further investigations are needed to determine whether it may help identify dogs with ADHAC-P requiring specific antiproteinuric treatment.

Evaluation of muscle mass and intramuscular fatty infiltration in dogs with hypercortisolism and their association with prognosis

BACKGROUND

Muscle atrophy and intramuscular fatty infiltration, as well as their association with prognosis, have not been quantified in dogs with spontaneous hypercortisolism (HC).

OBJECTIVE

To quantitatively evaluate muscle atrophy and IM fatty infiltration in dogs with HC and determine their prognostic impact.

ANIMALS

Fifty-three dogs with HC and 66 control dogs without HC.

METHODS

Retrospective cohort study. Medical records and computed tomography images obtained between 2014 and 2021 were evaluated. Kaplan-Meier curves and log-rank tests were used to analyze the effect of muscle atrophy and IM fatty infiltration on the prognosis of dogs with HC.

RESULTS

Dogs with HC showed lower visually measured cross-sectional area (VCSA) and cross-sectional area based on attenuation (HCSA) than control dogs (median [interquartile range {IQR}]: 50.3 mm2/mm [36.2-67.8] vs 66.7 mm2/mm [48.0-85.9]; P < .001; 30.4 mm2/mm [13.7-57.2] vs 54.8 mm2/mm [39.7-71.5]; P < .001, respectively). Dogs with HC had lower epaxial muscle attenuation (L3HU) than control dogs (median [IQR]: 21.2 Hounsfield [HU] [12.4-28.2] vs 33.2 HU [22.6-43.6]; P < .001). Dogs with HC with lower HCSA or L3HU had shorter survival (median [IQR]: 670 days [222-673] vs 949 days [788-1074], P < .01; 523 days [132-670] vs 949 days [756-1074], P < .01, respectively) but not lower VCSA (median [IQR]: 673 days [132-788] vs 949 days [523 to not applicable]; P = .30).

CONCLUSION AND CLINICAL IMPORTANCE

Hypercortisolism in dogs causes muscle atrophy and IM fatty infiltration and is associated with poor prognosis.

Treatment of Ezetimibe lowers total and low-density lipoprotein cholesterol in hypercholesterolemic dogs with hyperadorenocorticism

Ezetimibe is a cholesterol absorption inhibitor that blocks the intestinal absorption of both biliary and dietary cholesterol, thereby lowering primarily low density lipoprotein-cholesterol (LDL-chol) in human studies. This study aimed to investigate the effects of ezetimibe on dyslipidemia control in nine dogs with hypercholesterolemia. Changes in total cholesterol (T-chol) and each lipoprotein fractions were evaluated at 0, 2, and 4 months following initiation of ezetimibe treatment. A significant decrease in T-chol was observed, and a mean T-chol concentration below 400 mg/dL was achieved at 2 and 4 months. Furthermore, a significant decrease in LDL-chol was observed (-53.3% and -64.3% at 2 and 4 months, respectively). Taken together, treatment of ezetimibe could lower LDL-chol levels in dogs with hypercholesterolemia.

Lipoprotein profiles in Miniature Schnauzer dogs with idiopathic hypertriglyceridemia and hypercortisolism

Miniature Schnauzer dogs (MSs) are predisposed to both idiopathic hypertriglyceridemia (iHTG) and hypercortisolism (HCort). To our knowledge, the lipoprotein profiles of MSs with iHTG have not been compared to those with HCort. We analyzed cholesterol and triglyceride concentrations and lipoprotein fractions in 4 groups of MSs: normotriglyceridemia (NTG) without concurrent disease (Healthy-NTG), HCort and NTG (HCort-NTG), HCort and HTG (HCort-HTG), and iHTG. Lipoprotein fractions were assessed by lipoprotein electrophoresis and compared between groups. Fifty-one plasma samples were analyzed. Twenty-five dogs had NTG (16 Healthy-NTG, 9 HCort-NTG) and 26 dogs had HTG (7 iHTG, 19 HCort-HTG). Dogs with iHTG or HCort-HTG had significantly higher cholesterol concentrations than Healthy-NTG dogs. Dogs with HCort-HTG had higher cholesterol than HCort-NTG dogs. There was a significantly higher low-density lipoprotein (LDL) percentage in iHTG and HCort-HTG dogs than HCort-NTG dogs. HCort-HTG dogs also had lower high-density lipoproteins (HDL) than HCort-NTG dogs. It was not possible to readily distinguish MSs with iHTG from MSs with HCort-HTG or Healthy-NTG using lipoprotein electrophoresis fractions. The diagnosis of iHTG remains a diagnosis by exclusion.

The effects of selected sedatives on basal and stimulated serum cortisol concentrations in healthy dogs

Background

Hormone assessment is typically recommended for awake, unsedated dogs. However, one of the most commonly asked questions from veterinary practitioners to the endocrinology laboratory is how sedation impacts cortisol concentrations and the adrenocorticotropic hormone (ACTH) stimulation test. Butorphanol, dexmedetomidine, and trazodone are common sedatives for dogs, but their impact on the hypothalamic-pituitary-adrenal axis (HPA) is unknown. The objective of this study was to evaluate the effects of butorphanol, dexmedetomidine, and trazodone on serum cortisol concentrations.

Methods

Twelve healthy beagles were included in a prospective, randomized, four-period crossover design study with a 7-day washout. ACTH stimulation test results were determined after saline (0.5 mL IV), butorphanol (0.3 mg/kg IV), dexmedetomidine (4 µg/kg IV), and trazodone (3-5 mg/kg PO) administration.

Results

Compared to saline, butorphanol increased basal (median 11.75 µg/dL (range 2.50-23.00) (324.13 nmol/L; range 68.97-634.48) vs 1.27 µg/dL (0.74-2.10) (35.03 nmol/L; 20.41-57.93); P < 0.0001) and post-ACTH cortisol concentrations (17.05 µg/dL (12.40-26.00) (470.34 nmol/L; 342.07-717.24) vs 13.75 µg/dL (10.00-18.90) (379.31 nmol/L; 275.96-521.38); P ≤ 0.0001). Dexmedetomidine and trazodone did not significantly affect basal (1.55 µg/dL (range 0.75-1.55) (42.76 nmol/L; 20.69-42.76); P = 0.33 and 0.79 µg/dL (range 0.69-1.89) (21.79 nmol/L; 19.03-52.14); P = 0.13, respectively, vs saline 1.27 (0.74-2.10) (35.03 nmol/L; 20.41-57.93)) or post-ACTH cortisol concentrations (14.35 µg/dL (range 10.70-18.00) (395.86 nmol/L; 295.17-496.55); (P = 0.98 and 12.90 µg/dL (range 8.94-17.40) (355.86 nmol/L; 246.62-480); P = 0.65), respectively, vs saline 13.75 µg/dL (10.00-18.60) (379.31 nmol/L; 275.86-513.10).

Conclusion

Butorphanol administration should be avoided prior to ACTH stimulation testing in dogs. Further evaluation of dexmedetomidine and trazodone's effects on adrenocortical hormone testing in dogs suspected of HPA derangements is warranted to confirm they do not impact clinical diagnosis.

Prevalence of Systemic Hypertension and Control of Systolic Blood Pressure in a Cohort of 14 Dogs with Adrenal-Dependent Hypercortisolism during the First Year of Trilostane Treatment or after Adrenalectomy

Hypercortisolism in dogs is frequently associated with systemic hypertension (SH). However, there are no studies evaluating the changes in systolic blood pressure (SBP) in dogs with adrenal-dependent hypercortisolism (ADH) during trilostane treatment or after adrenalectomy and their response to antihypertensive treatments. For this reason, the objectives of this study were to evaluate the changes in SBP in dogs with ADH during the first year of trilostane treatment or after adrenalectomy, the relation with clinical control of hypercortisolism and certain laboratory parameters, and the response to antihypertensive drugs. Fourteen dogs newly diagnosed with ADH were prospectively included and evaluated at diagnosis (T0) and 1, 3, 6, and 12 months after (T1, T3, T6, and T12, respectively). Dogs were classified as hypertensive (HT; SBP ≥ 160 mmHg) and non-hypertensive. In HT dogs, benazepril was considered as the first-line drug, and, if necessary, amlodipine was prescribed. The prevalence of SH at T0 was 79%, and it was reduced to 25% at T12. Blood pressure (BP) was not associated with disease control or selected laboratory parameters at any endpoint. Only 22% of dogs with SH needed more than one drug to normalize their SBP. In all dogs surgically treated that were HT at T0, BP normalized at T3.

The impact of single-dose trazodone administration on plasma endogenous adrenocorticotropic hormone and serum cortisol concentrations in healthy dogs

BACKGROUND

Conditions affecting the hypothalamic-pituitary-adrenal (HPA) axis are common in dogs. Testing the function of the HPA axis includes measurement of endogenous adrenocorticotropic hormone (eACTH) and performance of an adrenocorticotropic hormone (ACTH) stimulation test. Trazodone is commonly administered to dogs to decrease stress. In humans, trazodone significantly decreases plasma cortisol concentration via alpha-1 adrenergic activity.

OBJECTIVES

Determine the influence of trazodone on eACTH and serum cortisol concentrations in healthy dogs.

ANIMALS

Fourteen healthy, adult, companion dogs.

METHODS

Prospective, randomized placebo-controlled study. Trazodone (8-10 mg/kg) or placebo was administered PO 1 hour before eACTH measurement and ACTH stimulation testing. After a ≥7-day wash-out period, dogs received the opposite treatment. Differences in eACTH, pre- and post-ACTH stimulation cortisol concentrations, and delta (difference between pre- and post-ACTH) cortisol concentrations were analyzed using a paired t or signed-rank test with a P < .05 significance level.

RESULTS

The eACTH concentrations were not significantly different (P = .23) between treatments. Similarly, no significant differences were found in the pre-ACTH cortisol concentrations between treatments (P = .40). Post-ACTH cortisol concentrations (P = .05) and delta cortisol concentrations (P = .04) were significantly lower when the dogs were treated with trazodone.

CONCLUSIONS

Preliminary data suggest trazodone administration dampens the adrenocortical response to stimulation in healthy dogs. If similar effects are found in dogs with adrenal disease, the use of trazodone may affect diagnosis and clinical decision making in these populations.

External validation of a United Kingdom primary-care Cushing's prediction tool in a population of referred Dutch dogs

BACKGROUND

A prediction tool was developed and internally validated to aid the diagnosis of Cushing's syndrome in dogs attending UK primary-care practices. External validation is an important part of model validation to assess model performance when used in different populations.

OBJECTIVES

To assess the original prediction model's transportability, applicability, and diagnostic performance in a secondary-care practice in the Netherlands.

ANIMALS

Two hundred thirty client-owned dogs.

METHODS

Retrospective observational study. Medical records of dogs under investigation of Cushing's syndrome between 2011 and 2020 were reviewed. Dogs diagnosed with Cushing's syndrome by the attending internists and fulfilling ALIVE criteria were defined as cases, others as non-cases. All dogs were scored using the aforementioned prediction tool. Dog characteristics and predictor-outcome effects in development and validation data sets were compared to assess model transportability. Calibration and discrimination were examined to assess model performance.

RESULTS

Eighty of 230 dogs were defined as cases. Significant differences in dog characteristics were found between UK primary-care and Dutch secondary-care populations. Not all predictors from the original model were confirmed to be significant predictors in the validation sample. The model systematically overestimated the probability of having Cushing's syndrome (a = -1.10, P < .001). Calibration slope was 1.35 and discrimination proved excellent (area under the receiver operating curve = 0.83).

CONCLUSIONS AND CLINICAL IMPORTANCE

The prediction model had moderate transportability, excellent discriminatory ability, and overall overestimated probability of having Cushing's syndrome. This study confirms its utility, though emphasizes that ongoing validation efforts of disease prediction tools are a worthwhile effort.

Serum Bile Acids Concentrations and Liver Enzyme Activities after Low-Dose Trilostane in Dogs with Hyperadrenocorticism

Hyperadrenocorticism (HAC) often leads to vacuolar hepatopathy. The impact of trilostane treatment on serum total bile acids (SBAs) concentrations in dogs with HAC remains unknown. This study investigated SBAs concentrations in healthy dogs and those with HAC following trilostane therapy. Ten healthy dogs and fifteen dogs with HAC were prospectively enrolled. A biochemistry profile and pre- and post-prandial SBAs concentrations were determined in each dog. Dogs with HAC were reassessed at 1 and 3 months after the initiation of trilostane treatment. Dogs with HAC had significantly higher serum ALT, ALP, and GGT activities, and cholesterol, triglyceride, and pre-prandial SBAs concentrations compared to healthy dogs. After 3 months of trilostane treatment, polyuria/polydipsia and polyphagia were completely resolved in 42.8% and 35.7%, respectively. Significant improvements in serum ALT and ALP activities and cholesterol concentrations were observed within 1-3 months of trilostane treatment. However, pre- and post-prandial SBAs concentrations did not significantly decrease. These findings suggest that treatment with low-dose trilostane for 3 months appears to reduce serum liver enzyme activities, but not SBAs concentrations. Further investigation is warranted to explore the effects of low-dose trilostane treatment on SBAs concentrations for a longer duration or after achieving appropriate post-ACTH cortisol levels.

Diagnostic cut-off values for the urinary corticoid:creatinine ratio for the diagnosis of canine Cushing's syndrome using an automated chemiluminescent assay

BACKGROUND

Cushing's syndrome is one of the most common endocrinopathies in dogs. The preferred screening test for spontaneous Cushing's syndrome is the low-dose dexamethasone suppression test (LDDST). The diagnostic value of urinary cortisol:creatinine ratios (UCCR) is questionable.

OBJECTIVES

The aim of this study was to determine diagnostic cut-off values for UCCR testing in comparison with LDDST as a clinical reference standard and to calculate the sensitivity and specificity.

METHODS

Data from 2018 to 2020 were obtained retrospectively from a commercial laboratory. Both LDDST and UCCR were measured by automated chemiluminescent immunoassay (CLIA). The maximum interval between both tests was 14 days. The optimal cut-off value for UCCR testing was calculated by the Youden index. The sensitivity and specificity of these cut-off values for the UCCR test and LDDST were assessed by Bayesian latent class models (BLCMs).

RESULTS

This study included 324 dogs with both UCCR test and LDDST results. The optimal UCCR cut-off value, calculated by the Youden index, was 47.4 × 10-6 . Any UCCR <40 × 10-6 was interpreted as a negative result, 40-60 × 10-6 as values in a gray zone, and >60 × 10-6 as positive. Using the cut-off of 60 × 10-6 , BLCM showed 91% (LDDST) and 86% (UCCR test) sensitivity and a specificity of 54% (LDDST) and 63% (UCCR test).

CONCLUSIONS

Considering an 86% sensitivity and a 63% specificity, UCCR testing may be considered a first-line investigation to rule out Cushing's syndrome using CLIA analysis. Urine samples can be collected noninvasively at home by the owner, reducing the potential impact of stress.

Laparoscopic vs. open adrenalectomy: perioperative data and survival analysis in 70 dogs with an adrenal tumor

Adrenalectomy is the treatment of choice in case of functional adrenal tumors and malignant adrenal incidentalomas. Laparoscopic adrenalectomy (LA) in dogs has gained popularity in recent years, however, clinical studies on large patient populations are scarce. This retrospective study describes perioperative and recurrence data, survival, and prognostic factors in 70 dogs that underwent LA or open adrenalectomy (OA) in our hospital between 2008 and 2022. Diagnosis was based on history, clinical signs, endocrine function tests and advanced diagnostic imaging. Laparoscopic adrenalectomy was performed in 42 dogs (n = 27 naturally occurring hypercortisolism, n = 4 pheochromocytoma, n = 1 pheochromocytoma with concurrent hypercortisolism, n = 10 incidentaloma) and OA in 28 dogs (n = 22 hypercortisolism, n = 3 pheochromocytoma, n = 3 incidentaloma). Bilateral adrenalectomy was performed in 8/70 dogs. Surgical duration of LA and OA did not differ significantly in unilateral and bilateral procedures (P = 0.108 and P = 0.101, respectively). Systemic hypertension occurred in 7/41 and 1/28 dogs during LA and OA, respectively (P = 0.130). Hypotension occurred in 2/41 and 4/28 dogs during LA and OA, respectively (P = 0.214). A total of 40/42 dogs in the LA group and 27/28 in the OA group survived to discharge (P = 0.810). Mean hospital stay was significantly shorter (P = 0.006) after LA (1.5 days, range 1-3) than after OA (2.2 days, range 1-4). No significant differences were demonstrated between LA and OA groups in recurrence of adrenal-dependent endocrine disease (P = 0.332), disease-free period (P = 0.733) and survival time (P = 0.353). The disease-specific 1-, 2- and 3-year survival rates were 95, 89, and 89% after LA and 92, 88, and 81% after OA. Tumor size was significantly associated with the occurrence of a recurrence. In addition, tumor size had a negative effect on the disease-free period and survival time. This study shows a favorable outcome of both LA and OA in dogs. Based on low perioperative complication rate, short hospitalization time and long-term outcomes comparable to OA in selected cases, the less invasive laparoscopic approach is considered the preferred technique.

Effects of concurrent canine Cushing's syndrome and diabetes Mellitus on insulin requirements, trilostane dose, and survival time

Trilostane and insulin requirements and survival time of dogs with concurrent naturally-occurring Cushing's syndrome (CS) and diabetes mellitus (DM) has not been fully investigated. This retrospective study evaluated trilostane and insulin doses in dogs with concurrent CS and DM compared to dogs with only CS or DM. Additionally, a survival analysis was performed using a Kaplan-Meier survival curve. Survival time was compared through Log-rank test. Cox proportional regression method was used to screen predictor factors of death in dogs with CS, DM or concurrent CS and DM. A total of 95 dogs were included, 47 dogs had CS, 31 dogs had DM and 17 dogs had concurrent CS and DM. After long-term follow-up, dogs with concurrent CS and DM required higher final median doses of insulin than dogs with DM [0.90 (0.73-1.1) vs 0.67 (0.55-0.73) u/kg/12 h; P = 0,002]. Conversely, the median trilostane requirements in dogs with concurrent CS and DM did not differ from the median trilostane requirements of dogs with CS [1.52 (0.76-2.80) vs 1.64 (1.19-4.95) mg/kg/day; P = 0.283]. No statistical difference was found for the median survival time between dogs with CS and dogs with concurrent CS and DM (1245 vs 892 days; p = 0.152). Although, median survival time of dogs with DM was not reached, it was longer than median survival time of dogs with CS and DM (892 days; P = 0.002). In conclusion, diabetic dogs with concurrent CS need higher insulin doses and have a shorter survival time compared to diabetic dogs without CS.

Impact of body weight and sex in selected dog breeds on the canine adrenal gland dimensions measured by computed tomographic imaging

BACKGROUND

The present study aimed to investigate possible influences of body weight and sex on adrenal gland size in endocrinologically healthy dogs. Possible factors influencing the adrenal size are discussed in relation to a universal upper reference value from the literature of 7.4 mm as the thickness in the caudal pole of the adrenal gland. The adrenal size was measured by computed tomography (CT) from 66 normal dogs of six different breeds (Labrador Retriever (n = 16), German Shepherd (n = 10), Boxer (n = 8), Beagle (n = 14), Dachshund (n = 6) and Jack Russell Terrier (n = 12); male n = 38 (thereof neutered n = 23), female n = 28 (thereof neutered n = 17)) based on volume quantification and linear measurements using the data processing software Amira. For interbreed comparability, a ratio consisting of the third root of adrenal volume to aortic diameter (Ratio volume-aorta, RVA) was introduced. Additionally, breed-related attenuation values in contrast-enhanced CT data sets were measured.

RESULTS

The measured volumes ranged from 0.34 to 1.93 cm3 for the right and from 0.39 to 2.23 cm3 for the left adrenal gland. The present study was able to demonstrate a body weight effect on the adrenal volume as well as on length and height. In terms of adrenal size, no significant differences between male and female, nor between intact and neutered dogs were obtained due to the RVA. In addition, for the weight classes, a breed independent threshold for dogs less (left 1.4; right gland 1.5) or more than 20 kg body weight (left 1.1; right gland 1.2) based on RVA was defined. Breed-related significant differences with respect to attenuation were determined only for the left adrenal gland, with lower attenuation values in large dog breeds.

CONCLUSION

The present study points out the importance of weight-related data when assessing CT data of the canine adrenal gland regarding volume, size and attenuation. The use of a universal reference value for the assessment of adrenal size appears unsuitable considering weight-related volume and linear measurements. Sex seems not to affect adrenal gland size.

Cushing Syndrome and Other Causes of Insulin Resistance in Dogs

The most common causes of insulin resistance in diabetic dogs are Cushing syndrome, diestrus, and obesity. Cushing-associated effects include insulin resistance, excessive postprandial hyperglycemia, perceived short duration of insulin action, and/or substantial within-day and/or day-to-day glycemic variability. Successful strategies to manage excessive glycemic variability include basal insulin monotherapy and combined basal-bolus insulin treatment. Ovariohysterectomy and insulin treatment can achieve diabetic remission in about 10% of cases of diestrus diabetes. Different causes of insulin resistance have an additive effect on insulin requirements and the risk of progression to clinical diabetes in dogs.

Clinical features of muscle stiffness in 37 dogs with concurrent naturally occurring hypercortisolism

BACKGROUND

Severe muscle stiffness (SMS) in dogs with hypercortisolism (HC) is uncommon.

OBJECTIVES

To evaluate signalment, presentation, treatments, and long-term outcomes of dogs with concurrent HC and SMS.

ANIMALS

Thirty-seven dogs.

METHODS

Medical records of dogs with HC and concurrent SMS were recruited from 10 institutions. Clinical information, test results, therapeutic responses, and survival times were reviewed.

RESULTS

All 37 dogs with HC and SMS had pituitary-dependent hypercortisolism (PDH); 36/37 weighed <20 kg. Signs and test results were typical of PDH aside from SMS, initially diagnosed in all 4 limbs in 9, pelvic limbs of 22, and thoracic limbs of 6 dogs. Hypercortisolism and SMS were diagnosed together in 3 dogs; HC 1-36 months before SMS in 23; SMS 1-12 months before HC in 11. Mitotane or trilostane, given to control HC in 36/37 dogs, improved or resolved HC signs in 28; SMS did not resolve, remaining static or worsening in 31/36 dogs, mildly improving in 5/19 dogs given additional therapies. Progression of SMS included additional limbs in 10 dogs and the masticatory muscles of 2. The median survival time from diagnosis of SMS was 965 days (range, 8-1188).

CONCLUSIONS AND CLINICAL IMPORTANCE

Concurrent SMS and HC is uncommon, possibly affecting only dogs with PDH. Development of SMS might occur before or after diagnosis of HC. Apart from SMS, the clinical picture and survival time of these dogs seem indistinguishable from those of dogs with HC in general. However, while muscle weakness usually resolves with HC treatment SMS does not.

Reference intervals for plasma, urinary, and salivary concentrations of free metanephrines in dogs: Relevance to the diagnosis of pheochromocytoma

BACKGROUND

Measurement of free metanephrines is recommended for screening of pheochromocytoma (PCC) but requires appropriate reference intervals (RIs).

HYPOTHESIS/OBJECTIVES

To report RIs for plasma, urinary and salivary concentrations of free metanephrines and to determine the diagnostic performance of plasma free normetanephrine (pNMN) and metanephrine (pMN) concentrations in dogs with PCC, hypercortisolism (HC), and nonadrenal illness (NAI).

ANIMALS

Eighty healthy dogs, 11 PCC dogs, 25 HC dogs, 6 NAI dogs.

METHODS

Plasma, urine, and saliva were collected prospectively from healthy dogs, and free metanephrine concentrations were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, medical records of dogs that had plasma free metanephrine concentrations measured by LC-MS/MS between 2018-2021 were studied retrospectively.

RESULTS

The RIs for free metanephrines in plasma, urine and saliva are reported. Dogs with PCC had significantly higher pNMN than dogs with HC (P < .001) and NAI (P = .002). The PCC dogs had significantly higher pMN than HC dogs (P < .001), but not higher than NAI dogs (P = .29). Using the upper reference limit, pNMN (>3.56 nmol/L) showed high sensitivity (100%, 95% confidence interval [CI]: 72-100) and specificity (94%, 95% CI: 79-99) for diagnosis of PCC, whereas pMN (>2.49 nmol/L) showed moderate sensitivity (73%, 95% CI: 39-94) and high specificity (94%, 95% CI: 79-99).

CONCLUSIONS AND CLINICAL IMPORTANCE

With establishment of these RIs, biochemical testing for PCC in dogs can be substantially improved. Measurement of pNMN is superior to pMN in dogs with PCC.

Re-evaluation of the low-dose dexamethasone suppression test in dogs

OBJECTIVES

This study aims to re-evaluate the low-dose dexamethasone suppression test 8-hour cortisol cut-point for the diagnosis of hypercortisolism in dogs using a solid-phase, competitive chemiluminescent enzyme immunoassay.

MATERIALS AND METHODS

Twenty-seven client-owned dogs with naturally occurring hypercortisolism and 30 healthy control dogs were prospectively recruited. Performance of the low-dose dexamethasone suppression test was assessed using sensitivity, specificity and a receiver operating characteristic curve compared to a clinical diagnosis of hypercortisolism including response to treatment.

RESULTS

Twenty-four dogs were diagnosed with pituitary-dependent hypercortisolism and three with adrenal-dependent hypercortisolism. In 30 healthy control dogs, 8-hour post-dexamethasone cortisol concentrations ranged from 5.5 to 39 nmol/L. A receiver operating characteristic curve curve constructed from the 8-hour post-dexamethasone cortisol concentrations of hypercortisolism and control dogs demonstrated that the most discriminatory cut-point was more than 39 nmol/L with sensitivity of 85.2% (95% confidence interval, 67.5% to 94.1%) and specificity of 100% (95% confidence interval, 88.7% to 100.0%) and an area under the curve of 0.963.

CLINICAL SIGNIFICANCE

The optimal cut-point of more than 36 nmol/L proposed by this study is similar to the currently accepted 8-hour cortisol concentration cut-point for diagnosing hypercortisolism when using a solid-phase, competitive chemiluminescent enzyme immunoassay.

Adrenocorticotropic hormone-producing pituitary adenoma with pituitary apoplexy treated by surgical decompression: a case report

Background

Pituitary-dependent hypercortisolism (PDH) is one of the most common endocrine disorders in veterinary medicine. However, there are few reports on pituitary tumor apoplexy (PTA) in dogs and no reports on its surgical intervention in veterinary medicine. Accordingly, the appropriate treatment is unknown. Herein, a case of PDH and PTA in a dog treated surgically is described.

Case presentation

A mongrel female dog (spayed; age, 8 years and 8 months; weight, 6.1 kg) with persistently elevated alkaline phosphatase underwent adrenocorticotropic hormone (ACTH) stimulation testing (post-stimulation cortisol: 20.5 μg/dL), abdominal ultrasonography (adrenal gland thickness: left, 5.7 mm; right, 8.1 mm), and brain magnetic resonance imaging (MRI) (pituitary-to-brain ratio [PBR], 0.61) at the referral hospital, resulting in a diagnosis of PDH (day 0). On day 9, the dog visited XXXX for the preparation of pituitary surgery to treat PDH. However, on days 10–15, the dog developed a loss of energy and appetite, bloody diarrhea, vomiting, and a decreased level of consciousness. However, on day 16, the dog’s condition recovered. A preoperative MRI scan performed on day 52 (the day of surgery) showed apoplexy in the dorsal pituitary region (PBR, 0.68). Based on the PTA findings, the risks of surgery were described to the owner, and approval was obtained. At the time of trans-sphenoidal surgery, a partial pituitary resection was performed with preservation of the PTA area due to adhesions between the PTA area of the right side of the pituitary and surrounding tissues. The resected pituitary tissue was diagnosed as an ACTH-producing adenoma, with necrotic and hemorrhagic findings. As of day 290, endogenous ACTH and cortisol levels did not exceed the reference range.

Conclusions

The acute signs that occurred on days 10–15 were most likely caused by PTA. Therefore, when signs similar to those detected in acute hypoadrenocorticism are observed in dogs with PDH, it is necessary to include PTA as a differential diagnosis. Trans-sphenoidal surgery may be effective in PDH-affected dogs that develop PTA, but careful attention should be paid to tissue adhesions secondary to hemorrhage that may occur after PTA.

Successful use of a benchtop fluorescent enzyme immunoassay analyzer to measure serum cortisol concentration as a screening test for hypoadrenocorticism in dogs

OBJECTIVE

To assess the diagnostic performance of a benchtop fluorescent enzyme immunoassay analyzer (AIA-360; Tosoh Bioscience Inc) for the measurement of serum cortisol concentration as a screening test for hypoadrenocorticism in dogs.

ANIMALS

173 client-owned dogs (20 with hypoadrenocorticism and 153 with nonadrenal illness).

PROCEDURES

Medical records of all dogs that underwent an ACTH stimulation test between June 2015 and October 2019 were reviewed retrospectively. Dogs were excluded if the ACTH stimulation test was performed on the basis of a suspicion of hypercortisolism, serum cortisol concentrations were measured using an analyzer other than the one assessed in the present study, or dogs had received medication known to affect the pituitary-adrenal axis in the 4 weeks1,2 preceding ACTH stimulation testing. The diagnostic performance of the benchtop analyzer was evaluated by calculating sensitivity, specificity, and likelihood ratios at various cutoff points.

RESULTS

Serum resting cortisol cutoff point concentrations of 0.8 μg/dL (22 nmol/L), 1 μg/dL (28 nmol/L), and 2 μg/dL (55 nmol/L) had a sensitivity of 100%. An optimal serum resting cortisol cutoff point of 0.58 μg/dL (16 nmol/L) had a sensitivity, specificity, and positive and negative likelihood ratios of 100%, 97%, and 30.6 and 0.0, respectively.

CLINICAL RELEVANCE

Findings indicated that previously derived cutoff points could be used with excellent sensitivity to exclude hypoadrenocorticism in this population of dogs when serum cortisol concentration was measured with the evaluated benchtop analyzer. An ACTH stimulation test may need to only be performed to diagnose hypoadrenocorticism if resting serum cortisol concentration is ≤ 0.58 μg/dL when measured with the evaluated benchtop analyzer.

Serum steroid profiling of hepatocellular carcinoma associated with hyperadrenocorticism in dogs: A preliminary study

Background

Hepatocellular carcinoma (HCC) is one of the most common primary liver tumors in humans and dogs. Excessive adrenocortical hormone exposure may cause steroid hepatopathy, which may develop into HCC. In our previous study, hyperadrenocorticism (HAC) was a highly concurrent disease in dogs with HCC. Therefore, this study hypothesized that adrenal steroid alterations might be involved in hepatocarcinogenesis and aimed to specify the relationship between HAC and HCC in dogs.

Materials and methods

This study included 46 dogs brought to the Hokkaido University Veterinary Teaching Hospital between March 2019 and December 2020. Owners gave their signed consent for blood collection on their first visit. A total of 19 steroids (14 steroids and 5 metabolites) in the baseline serum of 15 dogs with HCC, 15 dogs with HAC, and 10 dogs with both diseases were quantitatively measured using the developed liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) method.

Results

In each group, 11 steroids were detected higher than 50%. The detection rate of steroid hormones did not significantly differ between the groups (p > 0.05). Principle component analysis (PCA) showed that the steroid profiles of the three groups were comparable. Median steroid hormone concentrations were not significantly different between the study diseases (p > 0.05).

Conclusion

The developed LC/MS/MS was useful for measuring steroid hormones. Although it was clear that HAC was concurrent in dogs with HCC, none of the serum steroids was suggested to be involved in HCC.

Evaluation of the ACTH stimulation test using a low dose of a depot formulation in healthy dogs and in dogs with untreated Cushing's syndrome

The sensitivity of the adrenocorticotropic hormone (ACTH) stimulation test to detect Cushing's Syndrome (CS) using a depot formulation needs to be evaluated. The aims of this study were to propose a reference interval (RI) for cortisol values 1-hour after administration of a low-dose of depot ACTH in healthy dogs, and to evaluate the sensitivity of this test to detect CS, differentiating among types of CS based on ultrasound findings. Forty-one healthy dogs (20 males, 21 females) were prospectively included. Additionally, 90 dogs with CS (31 males, 59 females) were retrospectively included. Dogs with CS were ultrasonographically classified as follows: 44 dogs with symmetrical adrenomegaly consistent with pituitary-dependent hypercortisolism (PDH), 8 dogs with unilateral adrenomegaly and atrophy of the contralateral adrenal gland or unilateral or bilateral adrenomegaly with malignancy features consistent with adrenal-dependent hypercortisolism (ADH), 34 dogs with equivocal adrenal asymmetry (EAA) and 4 dogs with normal adrenal thickness. In healthy dogs, lower and upper limit of the 95% RI for 1-hour post-ACTH cortisol concentration and their 90% confidence intervals, were 4.4 (2.7-5.8) μg/dl and 18.4 (16.5-20.0) μg/dl, respectively. Post-ACTH cortisol concentration was above the RI in 90.0% (ci95%, 76.1-100) of dogs with CS. An elevated post-ACTH cortisol concentration was detected in 95.5% (ci95%, 76.1-100) of dogs with PDH, 62.5% (ci95%, 46.1-78.9) of dogs with ADH and 88.2% (ci95%, 69.1-100) of dogs with EAA. The sensitivity of the ACTH stimulation test using a low-dose of depot ACTH in high in dogs with CS.

Inverse relationship between eosinophil profiles and serum glucose concentration in dogs with naturally occurring hypercortisolism

Hyperglycemia and eosinopenia are well-known characteristics of hypercortisolism (HC) in humans, however, their association in dogs with HC has rarely been reported. This study aimed to evaluate the association between eosinophils and serum fasting glucose concentration in dogs with HC. Forty-seven dogs with HC and 43 dogs with non-adrenal illness were included. In this retrospective cohort study, the complete blood count, blood chemistry profile, and pre- and post-adrenocorticotropic hormone (ACTH) cortisol concentrations were analyzed. Significant differences were found in neutrophil, monocyte, eosinophil, and platelet counts; eosinophil percentage; neutrophil-to-lymphocyte ratio; aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase activities (P < 0.05) between the groups. In dogs with HC, the eosinophil percentage was inversely correlated with fasting blood glucose (r = -0.3515, P = 0.0154) and post-ACTH cortisol concentrations (r = -0.6509, P < 0.0001). The neutrophil-to-lymphocyte ratio was inversely correlated with the eosinophil percentage (r = -0.4573, P = 0.0012) and count (r = -0.3688, P = 0.0108), but positively correlated with the fasting blood glucose level (r = 0.3888, P = 0.0069). Such correlations were not identified in dogs with non-adrenal illness. A multivariate analysis showed that only eosinophil percentage was associated with the presence of hyperglycemia in dogs with HC (odds ratio = 2.100, 95% confidence interval = 1.051-4.199, P = 0.0360). Therefore, eosinopenia induced by excess cortisol might be associated with altered glucose metabolism in dogs with HC. A better understanding of this correlation could be valuable to predict and prevent the complications of HC.

Canine urinary lactate and cortisol metabolites in hypercortisolism, nonadrenal disease, congestive heart failure, and health

Spontaneous hypercortisolism (HC) is a common endocrine disease of senior dogs, often overlapping in selected clinical signs and hematologic and blood biochemical abnormalities with nonadrenal diseases (NADs). HC and NAD could differentially affect cortisol metabolism, which is a complex 10-enzymatic pathway process. HC might also affect blood and urine lactate levels through its effects on mitochondrial function. We aimed to differentiate between HC and NAD via a urinary cortisol metabolites and lactate panel. We prospectively recruited 7 healthy dogs and 18 dogs with HC, 15 with congestive heart failure (CHF), and 9 with NAD. We analyzed urine by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. We normalized urinary lactate and cortisol metabolites to urine creatinine concentration, and then compared groups using a linear-mixed model and principal component (PC) analysis. A machine-learning classification algorithm generated a decision tree (DT) model for predicting HC. The least-squares means of normalized urinary 6β-hydroxycortisol and PC1 of the HC and CHF groups were higher than those of the healthy and NAD groups (p = 0.05). Creatinine-normalized urinary 6β-hydroxycortisol had better sensitivity (Se, 0.78; 95% CI: 0.55-0.91), specificity (Sp, 0.89; 95% CI: 0.57-0.99), and a likelihood ratio (LR; 7), than the Se (0.72; 95% CI: 0.49-0.88), Sp (0.89; 95% CI: 0.57-0.99), and LR (6.5) of PC1 for distinguishing HC from NAD. Lactate and dihydrocortisone had the highest decreasing node-weighted impurity value and were considered the most important features in the DT model; dihydrocortisol had no role in determining whether a dog had HC.

Effects of ACTH-Induced Long-Term Hypercortisolism on the Transcriptome of Canine Visceral Adipose Tissue

Cushing’s syndrome, or hypercortisolism (HC), a common endocrinopathy in adult dogs, is caused by chronic hypercortisolemia. Among different metabolic disorders, this syndrome is associated with enhanced subcutaneous lipolysis and visceral adiposity. However, effects of HC in adipose tissue, especially regarding visceral adipose tissue (VAT), are still poorly understood. Herein, the transcriptomic effects of chronic HC on VAT of dogs were evaluated. For this, subcutaneously implanted ACTH-releasing pumps were used, followed by deep RNA sequencing of the canine VAT. Prolonged HC seems to affect a plethora of regulatory mechanisms in VAT of treated dogs, with 1190 differentially expressed genes (DEGs, p and FDR < 0.01) being found. The 691 downregulated DEGs were mostly associated with functional terms like cell adhesion and migration, intracellular signaling, immune response, extracellular matrix and angiogenesis. Treatment also appeared to modulate local glucocorticoid and insulin signaling and hormonal sensitivity, and several factors, e.g., TIMP4, FGF1, CCR2, CXCR4 and HSD11B1/2, were identified as possible important players in the glucocorticoid-related expansion of VAT. Modulation of their function during chronic HC might present interesting targets for further clinical studies. Similarities in the effects of chronic HC on VAT of dogs and humans are highlighted.

Survival of dogs with pituitary-dependent hyperadrenocorticism treated twice daily with low doses of trilostane

BACKGROUND

Twice daily low trilostane doses have proven to be effective to manage canine Cushing's syndrome. However, survival and prognostic factors in dogs treated with this protocol have not been evaluated. The aim of the study was to evaluate survival and prognostic factors, including systolic blood pressure (SBP) at diagnosis, in dogs with pituitary-dependent hypercortisolism (PDH) treated with low trilostane doses.

METHODS

Medical records of 91 dogs newly diagnosed with PDH initially treated with 0.2-1.1 mg/kg of trilostane twice daily were retrospectively included. Survival times were calculated using the Kaplan-Meier estimator. Univariable and multivariable analysis were performed using the Cox proportional hazard regression analysis.

RESULTS

Overall, median survival was 998 days (range 26-1832 days, 95% confidence interval = 755-1241 days). In the multivariable analysis, age (hazard ratio [HR] = 1.337, p < 0.001), presence of calcinosis cutis (HR = 5.271, p < 0.001), body condition score (BCS) ≤3/9 (HR = 8.100, p < 0.001) and higher platelet count (HR = 1.002, p = 0.022) were negatively correlated with survival. SBP was not associated with survival.

CONCLUSIONS

Low-dose trilostane treatment twice daily provides slightly longer survival than previously reported for dogs with PDH treated once or twice daily at higher doses. Older age, presence of calcinosis cutis, low BCS and higher platelet count, but not systemic hypertension, are predictive of poorer prognosis in dogs with PDH.

Serum Lipidome Signatures of Dogs with Different Endocrinopathies Associated with Hyperlipidemia

Hyperlipidemia (hypertriglyceridemia, hypercholesterolemia) is a common finding in human and veterinary patients with endocrinopathies (e.g., hypothyroidism and hypercortisolism (Cushing's syndrome; CS)). Despite emerging use of lipidomics technology in medicine, the lipid profiles of these endocrinopathies have not been evaluated and characterized in dogs. The aim of this study was to compare the serum lipidomes of dogs with naturally occurring CS or hypothyroidism with those of healthy dogs. Serum samples from 39 dogs with CS, 45 dogs with hypothyroidism, and 10 healthy beagle dogs were analyzed using a targeted lipidomics approach with liquid chromatography-mass spectrometry. There were significant differences between the lipidomes of dogs with CS, hypothyroidism, and the healthy dogs. The most significant changes were found in the lysophosphatidylcholines, lysophosphatidylethanolamines, lysophosphatidylinositols, phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols, ceramides, and sphingosine 1-phosphates. Lipid alterations were especially pronounced in dogs with hypothyroidism. Several changes suggested a more atherogenic lipid profile in dogs with HT than in dogs with CS. In this study, we found so far unknown effects of naturally occurring hypothyroidism and CS on lipid metabolism in dogs. Our findings provide starting points to further examine differences in occurrence of atherosclerotic lesion formation between the two diseases.

Total observed error, total allowable error, and QC rules for canine serum and urine cortisol achievable with the Immulite 2000 Xpi cortisol immunoassay

Determining a simple quality control (QC) rule for daily performance monitoring depends on the desired total allowable error (TEa) for the measurand. When no consensus TEa exists, the classical approach of QC rule validation cannot be used. Using the results of previous canine serum and urine cortisol validation studies on the Immulite 2000 Xpi, we applied a reverse engineering approach to QC rule determination, arbitrarily imposing sigma = 5, and determining the resulting TEa for the QC material (QCM; TEa_QCM) and the resulting probability of error detection (P_ed) for each QC rule. For the simple QC rule 1_2.5S with P_ed = 0.96 and probability of false rejection (P_fr) = 0.03, the associated TEa_QCM were 20% and 35% for serum and 28% and 24% for urine QCM1 and QCM2. If these levels of TEa_QCM are acceptable for interpretation of patient sample results, then users can internally validate the 1_2.5S QC rule, provided that their QCM CVs and biases are similar to ours. Otherwise, more stringent QC rules can be validated by using a lower sigma to lower the TEa_QCM. With spiked samples (relevant cortisol concentrations in the veterinary patient matrix) at 38.6 and 552 nmol/L of cortisol, TEa_QCM at sigma = 5 were much higher (54% and 40% for serum; 90.3% and 42.8% for urine). Spiked samples generate TEa that is probably too high to be suitable for daily QC monitoring; however, it is crucial to verify spiked sample observed total error (TEo; 26% and 18% for serum, 60% and 30% for urine) < TEa_QCM, and to use spiked sample TEo for patient result interpretation. In the absence of consensus TEa for cortisol in dogs, we suggest the use of a 1_2.5S rule, provided that users accept the associated level of TEa_QCM also as clinical TEa for results interpretation.

Urinary cortisol-creatinine ratio in dogs with hypoadrenocorticism

Background

Basal serum cortisol (BSC) ≥2 μg/dL (>55 nmol/L) has high sensitivity but low specificity for hypoadrenocorticism (HA).

Objective

To determine whether the urinary corticoid:creatinine ratio (UCCR) can be used to differentiate dogs with HA from healthy dogs and those with diseases mimicking HA (DMHA).

Animals

Nineteen healthy dogs, 18 dogs with DMHA, and 10 dogs with HA.

Methods

Retrospective study. The UCCR was determined on urine samples from healthy dogs, dogs with DMHA, and dogs with HA. The diagnostic performance of the UCCR was assessed based on receiver operating characteristics (ROC) curves, calculating the area under the ROC curve.

Results

The UCCR was significantly lower in dogs with HA (0.65 × 10⁻⁶; range, 0.33‐1.22 × 10⁻⁶) as compared to healthy dogs (3.38 × 10⁻⁶; range, 1.11‐17.32 × 10⁻⁶) and those with DMHA (10.28 × 10⁻⁶; range, 2.46‐78.65 × 10⁻⁶) (P < .0001). There was no overlap between dogs with HA and dogs with DMHA. In contrast, 1 healthy dog had a UCCR value in the range of dogs with HA. The area under the ROC curve was 0.99. A UCCR cut‐off value of <1.4 yielded 100% sensitivity and 97.3% specificity in diagnosing HA.

Conclusions and Clinical Importance

The UCCR seems to be a valuable and reliable screening test for HA in dogs. The greatest advantage of this test is the need for only a single urine sample.

Plasma sodium and potassium concentrations after hypophysectomy in dogs with corticotroph adenomas

Background

Electrolyte abnormalities, especially hypernatremia, are frequent complications after transsphenoidal hypophysectomy in dogs with pituitary‐dependent hypercortisolism.

Objectives

To describe electrolyte abnormalities after transsphenoidal hypophysectomy and to investigate possible associations between postoperative hypernatremia and clinical and surgical variables as well as with postoperative outcome.

Animals

One hundred and twenty‐seven client‐owned dogs.

Methods

Dogs with pituitary corticotroph adenomas that underwent transsphenoidal hypophysectomy were retrospectively included. Plasma sodium and potassium concentrations were measured −2, +2, +8, +24, and +48 hours from hypophysectomy. Clinical (breed, age, body weight, skull type, urinary cortisol/creatinine ratio, percentage of suppression to dexamethasone) and surgical variables (duration of anesthesia and surgery, pituitary dimensions) were compared to the development of hypernatremia.

Results

Postoperative hypernatremia developed in 46.5% (57/127) of dogs and hyponatremia in 6.3% (8/127). Plasma sodium concentration increased after surgery and peaked at 8 hours after surgery, normalizing after 24 to 48 hours. Plasma potassium concentration increased without exceeding the reference limit.

No significant associations were found between clinical and surgical variables and hypernatremia, or between hypernatremia and postoperative death, long‐term survival or recurrence.

Surgery time was significantly longer in dogs that developed persistent diabetes insipidus (P = .02) and persistent diabetes insipidus occurred more frequently in dogs with enlarged pituitary glands (P = .01).

Conclusion and Clinical Importance

Hypernatremia remains a frequent postoperative complication after transsphenoidal hypophysectomy but did not appear to have an impact on postoperative outcome. No predisposing factor to postoperative hypernatremia was identified. Variations in plasma potassium concentrations do not seem to influence postoperative outcome.

Frequency and risk factors for naturally occurring Cushing's syndrome in dogs attending UK primary-care practices

Objectives

To estimate the frequency and risk factors for Cushing's syndrome in dogs under UK primary veterinary care.

Materials and Methods

Dogs with Cushing's syndrome were identified by searching electronic patient records of primary‐care veterinary practices. Pre‐existing and incident cases of Cushing's syndrome during 2016 were included to estimate the 1‐year period prevalence. Incident cases were used to estimate the annual incidence and to identify demographic risk factors for the diagnosis of Cushing's syndrome in dogs, through multivariable logistic regression.

Results

Analysis included 970 pre‐existing and 557 incident cases of Cushing's syndrome from a population of 905,544 dogs. The estimated 1‐year period prevalence for Cushing's syndrome in dogs under veterinary care was 0.17% (95% confidence interval 0.16 to 0.18) and incidence was 0.06% (95% confidence interval 0.05 to 0.07). In multivariable logistic regression modelling, the Bichon frise (odds ratio=6.17, 95% confidence interval 4.22 to 9.00), Border terrier (5.40, 95% confidence interval 3.66 to 7.97) and Miniature schnauzer (3.05, 95% confidence interval 1.67 to 5.57) had the highest odds of Cushing's syndrome. The Golden retriever (0.24, 95% confidence interval 0.06 to 0.98) and Labrador retriever (0.30, 95% confidence interval 0.17 to 0.54) were the most protected breeds. Increasing age, bodyweight greater than the breed‐sex mean and being insured also showed increased odds of Cushing's syndrome.

Clinical Significance

As Cushing's syndrome is predominately diagnosed and managed in primary‐care practice, this study provides valuable new information of its epidemiology in this setting. Demographics reported are supportive of previous work and additional novel associations identified, such as the Border terrier, could enhance the index of suspicion for veterinarians.

Cushing's syndrome caused by intra-adrenocortical adrenocorticotropic hormone in a dog

A 13‐year‐old Labrador retriever was diagnosed with Cushing's syndrome (CS) caused by primary bilateral nodular adrenocortical hyperplasia with adrenocorticotropic hormone (ACTH) expression. The pituitary origin of CS was ruled out by suppression of plasma ACTH concentration and absence of a proliferative lesion on histological evaluation of the pituitary gland using periodic acid‐Schiff (PAS) staining, reticulin staining, and immunostaining for ACTH. A pheochromocytoma also was found at necropsy examination. On histological evaluation of both adrenal glands, at the junction of the fascicular and glomerular zones, multiple cell clusters distributed in both hyperplastic adrenal cortices expressed ACTH, whereas the pheochromocytoma cells did not. These results indicate that a disease similar to primary bilateral macronodular adrenocortical hyperplasia in humans also occurs in dogs, with intra‐adrenocortical expression of ACTH, glucocorticoids excess, and clinical signs of CS. Therefore, the term ACTH‐independent could be inappropriate in some cases of bilateral adrenocortical hyperplasia and suppressed plasma ACTH concentration in dogs.