Clinical characteristics, treatment, and outcomes of hypoadrenocorticism in dogs

OBJECTIVES

To determine the long-term survival of dogs with hypoadrenocorticism during the period that desoxycorticosterone pivalate has become widely used. Secondary goals were to compare age at diagnosis, median survival times, and age at death for dogs with hyponatraemic and/or hyperkalaemic hypoadrenocorticism and eunatraemic eukalaemic hypoadrenocorticism, and to determine the frequency of glucocorticoid-related side effects in these dogs.

MATERIALS AND METHODS

Retrospective cohort study with data collected from medical records and from a questionnaire sent to owners of affected dogs.

RESULTS

141 cases were identified; 125 had spontaneous hypoadrenocorticism and 16 had iatrogenic hypoadrenocorticism secondary to treatment of hyperadrenocorticism. Dogs with spontaneous hyponatraemic and/or hyperkalaemic hypoadrenocorticism were significantly younger at the time of diagnosis (median age: 5.1, range: 0.8 to 14.1 years, n = 97) compared to dogs with spontaneous eunatraemic eukalaemic hypoadrenocorticism (median age: 8.3, range: 3.0 to 12.7 years, n = 26). Sixty-six dogs were included in the survival analysis. For dogs with spontaneous hyponatraemic and/or hyperkalaemic hypoadrenocorticism, all of which were managed with desoxycorticosterone pivalate, median survival time was 5.7 years (95% CI: 4.0 to 7.2 years; n = 47) and median age at death was 11.0 years (range: 4.0 to 17.0 years; n = 30). For dogs with spontaneous eunatraemic eukalaemic hypoadrenocorticism, median survival time was 5.6 years (95% CI: 4.1-N/A years; n = 9) and median age at death was 11.8 years (range: 11.0 to 13.0 years; n = 4). The majority of owners that completed the questionnaire reported side effects commonly associated with glucocorticoid therapy.

CLINICAL SIGNIFICANCE

Hypoadrenocorticism carries an excellent prognosis. Desoxycorticosterone pivalate was the most frequently used mineralocorticoid therapy in this group of dogs.

Genetic models of Cushing's disease : From cells, in vivo transgenic models to human pituitary organoids

Cushing's disease (CD) is caused by pituitary tumors that overproduce adrenocorticotropic hormone (ACTH); however, effective medical treatments remain limited, significantly impairing patients' quality of life and prognosis. Despite extensive molecular analyses, the pathogenesis of CD remains unclear. Although previous molecular studies have relied heavily on rodent-derived cells and rodent transgenic models, significant species differences exist in the tumorigenesis of CD between humans and rodents. To date, an established human CD cell model is lacking, as human CD cells are limited in availability and sustainability over time. Additionally, the gene modifications used in transgenic models do not necessarily reflect the causative genes in CD. CD tumors exhibit wide phenotypic heterogeneity, which further complicates the development of an ideal genetic model. In this review, we provide an analysis of 11 genetic models used to study CD, outlining their historical development, strengths, and limitations. Additionally, we discuss the ongoing development of human induced pluripotent stem cell (iPSC)-derived pituitary organoids and further describe various models of pituitary organoids as an emerging novel approach to studying CD. By comparing all these models, we highlight the necessity of advancing genetic models to improve our understanding and treatment of CD.

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.

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.

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%.

(Un)Tying the Knot: Oxidative Stress, Inflammatory Markers, and Lipid Status in Dogs with Hypercortisolism

The aim of this study was to revisit the complex relationship between inflammation, oxidative stress and lipid metabolism in dogs with hypercortisolism (HC). Fourteen dogs newly diagnosed with HC and an equal number of healthy counterparts of similar age and markers of oxidative stress (AOPP, TBARS, TAC, GSH, PON-1, and UA) and inflammation (NLR, PLR, SII, HPT, CHE, CP, and Hcy) were included in the study. To determine the lipid profiles, cholesterol, and triglyceride levels were measured, and the electrophoretic separation of lipoproteins was performed. The results revealed that dogs with HC had higher levels of AOPP and TBARS, but only greater levels of GSH among antioxidants. Uric acid levels were higher in HC dogs, suggesting a pro-oxidative role. Elevated NLR, PLR, SII, and HPT levels were detected, but they did not seem to be associated with inflammation. Notable changes were detected in the HDL fraction, alongside hypercholesterolaemia and hypertriglyceridaemia. Correlation analysis revealed links between lipid markers and both oxidative stress and inflammatory indices. In conclusion, the data acquired may prove useful in further understanding of the intricate pathophysiology of Cushing's syndrome.

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.

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.

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.

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.

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.

Transcriptome sequencing reveals two subtypes of cortisol-secreting adrenocortical tumours in dogs and identifies CYP26B1 as a potential new therapeutic target

Cushing's syndrome (CS) is a serious endocrine disorder that is relatively common in dogs, but rare in humans. In ~15%-20% of cases, CS is caused by a cortisol-secreting adrenocortical tumour (csACT). To identify differentially expressed genes that can improve prognostic predictions after surgery and represent novel treatment targets, we performed RNA sequencing on csACTs (n = 48) and normal adrenal cortices (NACs; n = 10) of dogs. A gene was declared differentially expressed when the adjusted p-value was <.05 and the log₂ fold change was >2 or < -2. Between NACs and csACTs, 98 genes were differentially expressed. Based on the principal component analysis (PCA) the csACTs were separated in two groups, of which Group 1 had significantly better survival after adrenalectomy (p = .002) than Group 2. Between csACT Group G1 and Group 2, 77 genes were differentially expressed. One of these, cytochrome P450 26B1 (CYP26B1), was significantly associated with survival in both our canine csACTs and in a publicly available data set of 33 human cortisol-secreting adrenocortical carcinomas. In the validation cohort, CYP26B1 was also expressed significantly higher (p = .012) in canine csACTs compared with NACs. In future studies it would be interesting to determine whether CYP26B1 inhibitors could inhibit csACT growth in both dogs and humans.

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.

QT interval instability and variability in dogs with naturally-occurring hypercortisolism

Hypercortisolism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with naturally-occurring hypercortisolism (NOHC), indices of variability and instability of the QT interval were retrospectively studied in 38 dogs with NOHC and prospectively studied in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the NOHC group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. The NOHC group was subdivided according to cortisol suppression pattern in the low-dose dexamethasone suppression test. All electrocardiographic indices of partial and absent suppression patterns were numerically higher than healthy dogs. QTv and TI were lower in the control group than in both NOHC subgroups. LTI and STI were lower in the CG than in the group with the partial suppression pattern. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result might indicate that the etiology of NOHC, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term and the long-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.

Ironing out the wrinkles and folds in the epidemiology of skin fold dermatitis in dog breeds in the UK

Skin fold dermatitis (intertrigo) is an inflammatory process of closely apposing skin surfaces. Extreme conformations towards folded skin in many dog breeds are linked with higher risk. Using anonymised primary-care veterinary data from the VetCompass Programme, this study aimed to report the frequency, demographic risk factors and clinical management for skin fold dermatitis in the UK. Risk factor analysis used random effects multivariable logistic regression modelling. From a study population of 905,553 dogs, the one-year period prevalence in dogs overall was 0.37% (95% CI 0.35–0.39). Diagnosis was supported by laboratory testing in 4.21% cases. Systemic antibiosis was used in 42.30% cases. Compared with crossbreed dogs, the most highly predisposed breeds were English Bulldog (odds ratio [OR] 49.07, 95% CI 37.79–63.70), French Bulldog (OR 25.92, 95% CI 19.62–34.26,) and Pug (OR 16.27, 95% CI 12.20–21.69). The most protected breeds were Yorkshire Terrier (OR 0.14, 95% CI 0.03–0.56), Border Collie (OR 0.31, 95% CI 0.11–0.84), Jack Russell Terrier (OR 0.53, 95% CI 0.30–0.92) and Labrador Retriever (OR 0.57, 95% CI 0.35–0.93). This study adds further evidence to the welfare concerns around high popularity of dog breeds with extreme conformations. The three breeds with by far the highest odds of skin fold dermatitis represent an extreme brachycephalic conformation.

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.

Evaluation of the accuracy of three-dimensionally printed patient-specific guides for transsphenoidal hypophysectomy in small-breed dogs

OBJECTIVE

To assess the accuracy of transsphenoidal hypophysectomy using 3-D printed patient-specific guides (3D-PSGs) in small-breed dogs.

ANIMALS

Heads obtained from the cadavers of 19 small-breed dogs (ex vivo portion of study) and 3 healthy adult (3 to 4 years) purpose-bred Beagles with a median body weight of 9.2 kg.

PROCEDURES

In the ex vivo study, CT images of the cadavers were collected. The position, width, and length of the pituitary fossa and the pilot hole (insertion angle and place) were measured. Using PSGs, 19 pilot holes were made for the pituitary gland fossa, and CT was performed to assess the position accuracy. In the in vivo study, 3 surgical windows from the pilot holes were made using PSGs. Repeated CT and MRI were performed to evaluate the safeness and effectiveness of PSGs, followed by necropsy.

RESULTS

In the ex vivo study, the median (interquartile range) difference between the pre- and postoperative insertion angles was 2° (0° to 3.5°) and the median deviation of the pilot hole was 0.46 mm (0 to 1.58 mm). In the in vivo study, the surrounding structures were not damaged, and favorable outcomes were evident in terms of the shape, size, and position of the surgical window.

CLINICAL RELEVANCE

3D-PSGs provided a safe and effective surgical window for transsphenoidal hypophysectomy. Our findings emphasized the applicability of PSGs in brain surgery, in terms of accuracy and effectiveness.

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.

Thiobarbituric acid reactive substances in dogs with spontaneous hypercortisolism

Thiobarbituric acid reactive substances (TBARS) are laboratory markers of oxidative stress, which can be used to evaluate the lipid peroxidation that characterizes cell membrane damage caused by excess free radicals. This prospective study aimed to assess TBARS as a parameter of lipid peroxidation in dogs with spontaneous hypercortisolism (HC) at the time of diagnosis, and after trilostane treatment. Furthermore, it aimed to investigate the correlations between TBARS levels, and laboratory and cardiovascular parameters. Sixteen dogs with HC were evaluated at 3 different time points: At diagnosis (T0), 6 mo after treatment (T1), and 12 mo after trilostane treatment (T2). A control group (n = 20) of dogs with a demographic profile similar to the HC group, but considered healthy was selected and evaluated. There was a significant difference (P < 0.001) in TBARS levels between the HC group at diagnosis (4.38 ± 1.16 nmoles MDA/mg protein) and the control group (2.15 ± 0.45 nmoles MDA/mg protein). Dogs in the HC group exhibited a significant reduction (P < 0.001) in TBARS levels after treatment. There was no significant difference in TBARS levels between the control group and the HC group at T1 and T2 evaluation. TBARS positively correlated with left atrial dimensions and hematocrit. The study demonstrates that lipid peroxidation is increased in canine HC and suggests that control of the disease is beneficial to normalize the state of oxidative stress.

Adrenal cortex stimulation with hCG in spayed female dogs with Cushing's syndrome: Is the LH-dependent variant possible?

Background:

The expression and overexpression of luteinizing hormone (LH) receptors in the canine adrenal gland cortex have been reported. Therefore, it was hypothesized that a LH-dependent form of Cushing’s syndrome (CS) could exist in dogs.

Aim:

To assess whether the adrenal gland post-ovariectomy (OVx) exhibits a greater response to adrenocorticotrophin (ACTH) stimulation; to evaluate whether the adrenal gland responds to human chorionic gonadotropin (hCG) stimulation by increasing the release of cortisol; and to consider whether hCG stimulus testing would be useful as a diagnosis for possible cases of LH-dependent CS.

Methods:

Cortisol concentrations were measured from healthy female dogs (n=16) at baseline and following ACTH stimulation before and 2 months after gonadectomy (OVx). Cortisol concentrations were also measured for female dogs with CS (n = 14) following administration of hCG (5000 IU). A post-hCG cortisol concentration greater than 140 nmol/l was used to define dogs with LH-dependent Cushing’s syndrome.

Results:

In normal female dogs, both pre- and post-stimulation cortisol concentrations increased following OVx (p = 0.002 and p = 0.0003, respectively). In female dogs with CS, cortisol concentrations increased following stimulation with hCG in 57% (8/14; p = 0.002). Age at the time of OVx was associated (p = 0.015) with the cortisol response to hCG [8 (5–9) years vs. 3.5 (2–6) years, p = 0.0013).

Conclusion:

Based on these results, an LH-dependent form of CS occurs in spayed female dogs, and that it is more likely to occur when female dogs are spayed later in life.

Histopathological frequency of canine hepatobiliary disease in the United Kingdom

OBJECTIVES

Canine hepatobiliary disease is common; however, data determining disease frequency and breed predispositions are lacking. The primary objective was to identify the frequency of different hepatobiliary disease in a United Kingdom population of dogs and consequently determine breeds at both an increased and decreased risk of hepatobiliary disease.

MATERIALS AND METHODS

Anonymised histopathology reports from a commercial veterinary diagnostic laboratory, which were submitted between August 2013 and February 2018, were analysed. Data were retrospectively categorised into hepatobiliary diseases according to World Small Animal Veterinary Association Standards and the breed, age and genders recorded. Cases with incomplete data or no definitive diagnosis were excluded. Breed predisposition was calculated using odds ratios and 95% confidence intervals against a United Kingdom-based control population of micro-chipped dogs.

RESULTS

Histopathology results from 4584 cases met inclusion criteria. The most frequent histological diagnoses were reactive hepatitis (n=770); chronic hepatitis (n=735) and reversible hepatocellular injury (n=589). A number of breeds were shown to be at an increased or decreased risk of individual liver diseases.

CLINICAL SIGNIFICANCE

This is the first study to document the histopathological frequency of hepatobiliary diseases in a large cohort of dogs in the United Kingdom, as well as novel possible breed and age predispositions. Despite multivariable analysis not being performed to account for confounding factors, this information hopes to inform and support future investigations for hepatic disease in particular breeds and potential predispositions.

Metabolic profiling of serum from dogs with pituitary-dependent hyperadrenocorticism

Hyperadrenocorticism (HAC) is one of the most common endocrine diseases in dogs characterized by excessive cortisol production caused by an adrenocorticotropic hormone (ACTH)-secreting tumor, namely pituitary-dependent HAC (PDH) or cortisol-secreting adrenal tumor. Metabolomics presents the ability to identify small molecule metabolites. Thus, the use of metabolomics techniques in canine PDH can provide information about the pathophysiology and metabolic changes in this disease. This study aimed to identify and compare differences in serum metabolites between dogs with PDH and healthy dogs. The metabolomic profile of 20 dogs diagnosed with PDH was compared with 20 healthy dogs using liquid chromatography/mass spectrometry (LC/MS), and metabolite discrimination was performed using partial least squares-discriminant analysis (PLS-DA), the variable important in projection (VIP) and fold changes (FC) group-wise comparisons. The hypergeometric test identified the significantly altered pathways. A total of 21 metabolites were found to be significantly different between the two groups. The major alterations were found in arachidonic and decanoic acid, and phospholipids related to phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI). These metabolites are related to insulin resistance and other complications (i.e. hypertension). Our results indicate that PDH produces changes in serum metabolites of dogs, and the knowledge of these changes can aid to better understanding of pathophysiological processes involved and contribute to potentially detect new biomarkers for this disease.

Machine-learning based prediction of Cushing's syndrome in dogs attending UK primary-care veterinary practice

Cushing’s syndrome is an endocrine disease in dogs that negatively impacts upon the quality-of-life of affected animals. Cushing’s syndrome can be a challenging diagnosis to confirm, therefore new methods to aid diagnosis are warranted. Four machine-learning algorithms were applied to predict a future diagnosis of Cushing's syndrome, using structured clinical data from the VetCompass programme in the UK. Dogs suspected of having Cushing's syndrome were included in the analysis and classified based on their final reported diagnosis within their clinical records. Demographic and clinical features available at the point of first suspicion by the attending veterinarian were included within the models. The machine-learning methods were able to classify the recorded Cushing’s syndrome diagnoses, with good predictive performance. The LASSO penalised regression model indicated the best overall performance when applied to the test set with an AUROC = 0.85 (95% CI 0.80–0.89), sensitivity = 0.71, specificity = 0.82, PPV = 0.75 and NPV = 0.78. The findings of our study indicate that machine-learning methods could predict the future diagnosis of a practicing veterinarian. New approaches using these methods could support clinical decision-making and contribute to improved diagnosis of Cushing’s syndrome in dogs.

Non-neoplastic anal sac disorders in UK dogs: Epidemiology and management aspects of a research-neglected syndrome

BACKGROUND

Non-neoplastic anal sac disorders (ASD) are frequent presentations for dogs in primary-care practice but evidence-based information on disease occurrence and risk is sparse. This study estimates prevalence, breed associations and other risk factors as well as reporting on clinical management.

METHODS

A cohort study of dogs attending VetCompass practices between 1 January 2013 and 31 December 2013. Risk factor analysis used multivariable logistic regression methods.

RESULTS

Of 104,212 dogs attending 110 UK practices, the 1-year period prevalence of ASD was 4.40% (95% CI: 4.22-4.57). Compared to crossbreds, six breeds showed increased odds of ASD (Cavalier King Charles spaniel, King Charles spaniel, Cockapoo, Shih-tzu, Bichon Frise and Cocker spaniel), and six breeds showed reduced odds (Labrador Retriever, Border collie, Staffordshire Bull Terrier, Lurcher, German Shepherd Dog and Boxer). Brachycephalic types had 2.6 times the odds for ASD compared to dolichocephalic types. Medication prescribed for ASD included antimicrobials (n = 480, 20.24%) and analgesics (n = 284, 11.97%). Anal sacculectomy was performed in under 1% of cases.

CONCLUSIONS

High prevalence, strong breed predispositions and evidence of severity suggested from the antimicrobial and analgesic therapies combined with current substantial knowledge gaps identify ASD as a key research-neglected syndrome in dogs.

Somatostatin Receptor as a Molecular Imaging Target in Human and Canine Cushing Disease

OBJECTIVES

Fluorescence-guided surgery may improve completeness of resection in transsphenoidal surgery for Cushing disease (CD) by enabling visualization of residual tumor tissue at the margins. In this review we discuss somatostatin receptors (SSTRs) as targets for fluorescence-guided surgery and overview existing SSTR-specific imaging agents. We also compare SSTR expression in normal pituitary and corticotrophinoma tissues from human and canine CD patients to assess canines as a translational model for CD.

METHODS

A PubMed literature search was conducted for publications containing the terms canine, somatostatin receptor, Cushing's disease, and corticotroph adenoma. SSTR expression data from each study was documented as the presence or absence of expression or, when possible, the number of tumors expressing a given SSTR subtype within a group of tumors being studied. Studies that used reverse transcription polymerase chain reaction to quantify SSTR expression were selected for additional comparative analysis.

RESULTS

SSTR5 is strongly expressed in human corticotroph adenomas and weakly expressed in surrounding pituitary parenchyma, a pattern not conclusively observed in canine patients. SSTR2 mRNA expression is similar in human normal pituitary and corticotrophinoma cells but may be significantly higher in canine normal pituitary tissue than in corticotroph tumoral tissue. Limited data were available on SSTR subtypes 1, 3, and 4.

CONCLUSIONS

Further studies must fill the knowledge gaps related to species-specific SSTR expression, so using canine CD as a translational model may be premature. We do conclude that the expression profile of SSTR5 (i.e., high local expression in pituitary adenomas relative to normal surrounding tissues) makes SSTR5 a promising molecular target for FGS.

Hypoadrenocorticism in dogs under UK primary veterinary care: frequency, clinical approaches and risk factors

Objectives

To estimate the frequency, clinical approaches and risk factors of hypoadrenocorticism in dogs under UK primary veterinary care.

Materials and Methods

Dogs diagnosed with hypoadrenocorticism were identified from the UK VetCompass™ programme by searching anonymised electronic patient records. Pre‐existing and newly diagnosed cases of disease during 2016 were included. Cases were further sub‐categorised as having a laboratory‐confirmed or presumed diagnosis of hypoadrenocorticism based on the information recorded in the electronic patient records. Descriptive data were manually extracted. Multivariable logistic regression methods were used to identify demographic risk factors.

Results

There were 177 hypoadrenocorticism cases identified from 905,543 dogs in 2016; 72 laboratory‐confirmed and 105 presumed. The 1‐year period prevalence for hypoadrenocorticism in all dogs was 0.06% (95% confidence interval: 0.05‐0.07%). The most common presenting clinical signs in laboratory‐confirmed dogs were lethargy (51/66, 77.3%), anorexia (48/66, 66.7%) and vomiting (48/66, 66.7%). Hyperkalaemia was reported in 47 of 53 (88.7%), hyponatraemia in 46 of 53 (86.8%). Median sodium: potassium ratio was 19.00 (interquartile range: 16.20‐20.60). Breed, age, neuter status and insurance status were associated with a laboratory‐confirmed diagnosis of hypoadrenocorticism. No sex association with hypoadrenocorticism was observed in the multivariable model. The standard poodle had 51.38 times the odds (95% CI: 14.49‐182.18) of hypoadrenocorticism compared with crossbreeds. The labradoodle and West Highland white terrier also had increased odds.

Clinical Significance

This is the first epidemiological study to report on hypoadrenocorticism in dogs within the UK primary‐care population. These results provide benchmark data of current veterinary activity relating to hypoadrenocorticism in primary‐care practices.

Pituitary tumour types in dogs and cats

Pituitary tumours are common in dogs and are being increasingly recognized in cats. Pituitary tumours are usually classified as adenomas and should only be classified as carcinomas when there is evidence of metastatic spread of the tumour, which is rare. Despite the benign nature of most pituitary tumours, they can still compress or invade neighbouring tissues. Pituitary tumours can be functional (hormonally active) or non-functional (hormonally silent). The aim of this review was to provide an overview of the different pituitary tumour types in dogs and cats that have been reported in the literature. In dogs, the most common pituitary tumour type is the corticotroph adenoma, which can cause pituitary-dependent hypercortisolism. In cats, the most common pituitary tumour is the somatotroph adenoma, which can cause hypersomatotropism, and the second-most common is the corticotroph adenoma. A lactotroph adenoma has been described in one dog, while gonadotroph, thyrotroph and null cell adenomas have not been described in dogs or cats. Hormonally silent adenomas are likely underdiagnosed because they do not result in an endocrine syndrome. Tools used to classify pituitary tumours in humans, particularly immunohistochemistry for lineage-specific transcription factors, are likely to be useful to classify canine and feline pituitary tumours of unknown origin. Future studies are required to better understand the full range of pituitary adenoma pathology in dogs and cats and to determine whether certain adenoma subtypes behave more aggressively than others. Currently, the mechanisms that underlie pituitary tumorigenesis in dogs and cats are still largely unknown. A better understanding of the molecular background of these tumours could help to identify improved pituitary-targeted therapeutics.

'Generation Pup' - protocol for a longitudinal study of dog behaviour and health

BACKGROUND

Despite extensive research, many questions remain unanswered about common problems that impact dog welfare, particularly where there are multiple contributing factors that can occur months or years before the problem becomes apparent. The Generation Pup study is the first longitudinal study of dogs that recruits pure- and mixed-breed puppies, aiming to investigate the relative influence of environmental and genetic factors on a range of health and behaviour outcomes, (including separation related behaviour, aggression to familiar/unfamiliar people or dogs and obesity). This paper describes the study protocol in detail.

METHODS

Prior to commencing recruitment of puppies, the study infrastructure was developed, and subject specialists were consulted to inform data collection methodology. Questionnaire content and timepoint(s) for data collection for outcomes and potential predictors were chosen with the aim of providing the best opportunity of achieving the aims of the study, subject to time and funding constraints. Recruitment of puppies (< 16 weeks, or < 21 weeks of age if entering the United Kingdom or Republic of Ireland through quarantine) is underway. By 23 January 2020, 3726 puppies had been registered, with registration continuing until 10,000 puppies are recruited. Data collection encompasses owner-completed questionnaires issued at set timepoints throughout the dog's life, covering aspects such as training, diet, exercise, canine behaviour, preventative health care, clinical signs and veterinary intervention. Owners can elect to submit additional data (health cards completed by veterinary professionals, canine biological samples) and/or provide consent for access to veterinary clinical notes. Incidence and breed associations will be calculated for conditions for which there is currently limited information (e.g. separation related behaviour). Multivariable statistical analysis will be conducted on a range of outcomes that occur throughout different life stages, with the aim of identifying modifiable risk factors that can be used to improve canine health and welfare.

DISCUSSION

The Generation Pup project is designed to identify associations between early-life environment, genotypic make-up and outcomes at different life stages. Modifiable risk factors can be used to improve canine health and welfare. Research collaboration with subject specialists is welcomed and already underway within the fields of orthopaedic research, epilepsy, epigenetics and canine impulsivity.

Changes in systolic blood pressure in dogs with pituitary dependent hyperadrenocorticism during the first year of trilostane treatment

Background

Systemic hypertension (SH) is common in dogs and humans with hypercortisolism and can persist after treatment.

Objectives

To evaluate changes in prevalence of SH and systolic blood pressure (SBP) in dogs with pituitary‐dependent hyperadrenocorticism (PDH) during the first year of trilostane treatment, its relationship with disease control and selected laboratory variables, and their response to antihypertensive treatment.

Animals

Fifty‐one dogs with PDH treated with trilostane Q12h.

Methods

Prospective case series study. Dogs were evaluated at diagnosis (T0) and 1, 3, 6, and 12 months (T12). Dogs were classified as nonhypertensive (SBP < 160 mm Hg) or hypertensive (SBP≥160 mm Hg) and subclassified according to target organ damage (TOD) risk. Hypertensive dogs were treated with benazepril and, if control of SH was not achieved, amlodipine was added.

Results

Prevalence of SH decreased from T0 (36/51) to T12 (17/37; P = .01). Changes in SBP during the study were influenced by the risk of TOD at T0. In severely hypertensive (SBP ≥ 180 mm Hg) dogs, the decrease in SBP was more pronounced whereas in normotensive (SBP < 140 mm Hg) dogs SBP increased slightly (P = .00). Blood pressure was not associated with disease control. Antihypertensive treatment was needed in 31/51 dogs, and in 13/31 dogs additional SH control with amlodipine was required. One third of nonhypertensive dogs at T0 required treatment with benazepril because SH developed during follow‐up.

Conclusions and Clinical Importance

In dogs with PDH, SBP should be measured at every visit, regardless of disease control or SBP at diagnosis. More than 1 drug may be necessary to manage SH in affected dogs.

Unravelling the health status of brachycephalic dogs in the UK using multivariable analysis

Brachycephalic dog breeds are regularly asserted as being less healthy than non-brachycephalic breeds. Using primary-care veterinary clinical data, this study aimed to identify predispositions and protections in brachycephalic dogs and explore differing inferences between univariable and multivariable results. All disorders during 2016 were extracted from a random sample of 22,333 dogs within the VetCompass Programme from a sampling frame of 955,554 dogs under UK veterinary care in 2016. Univariable and multivariable binary logistic regression modelling explored brachycephaly as a risk factor for each of a series of common disorders. Brachycephalic dogs were younger, lighter and less likely to be neutered than mesocephalic, dolichocephalic and crossbred dogs. Brachycephalic differed to non-brachycephalic types in their odds for 10/30 (33.33%) common disorders. Of these, brachycephalic types were predisposed for eight disorders and were protected for two disorders. Univariable and multivariable analyses generated differing inference for 11/30 (30.67%) disorders. This study provides strong evidence that brachycephalic breeds are generally less healthy than their non-brachycephalic counterparts. Results from studies that report only univariable methods should be treated with extreme caution due to potential confounding effects that have not been accounted for during univariable study design or analysis.

Epidemiology of recurrent seizure disorders and epilepsy in cats under primary veterinary care in the United Kingdom

Background

Little epidemiological evaluation of recurrent seizure disorders in cats currently exists in veterinary literature.

Objectives

To report the prevalence and risk factors for recurrent seizure disorders (RSD) and epilepsy in cats presented to primary care veterinary practices in the United Kingdom (UK).

Animals

A total of 285 547 cats under veterinary care during 2013 presenting to 282 primary care clinics in the UK.

Methods

Cohort study using multivariable logistic regression modeling for risk factor analysis.

Results

There were 458 confirmed RSD cases, giving a 1‐year period prevalence of 0.16% (95% confidence interval [CI], 0.15‐0.18). A subset of 114 (24.89%) cases was recorded as having epilepsy, giving a 1‐year period prevalence of 0.04% (95% CI, 0.03‐0.5). Increasing age was significantly associated with increasing odds of RSD. Breed, sex, neuter status, and body weight were not associated with RSD. Epilepsy was most frequently diagnosed in adult to middle‐aged cats. Cats aged 3.0 to <6.0 years had 3.32 times higher odds of epilepsy diagnosis compared to cats <3.0 years of age. Insured cats were more likely to be diagnosed with epilepsy compared to noninsured cats.

Conclusions and Clinical Importance

Although less common than in dogs, RSD and epilepsy still comprise an important disorder group in the UK cat population. Aging is a significant risk factor for these disorders in cats.

Development and internal validation of a prediction tool to aid the diagnosis of Cushing's syndrome in dogs attending primary-care practice

BACKGROUND

Novel methods to aid identification of dogs with spontaneous Cushing's syndrome are warranted to optimize case selection for diagnostics, avoid unnecessary testing, and ultimately aid decision-making for veterinarians.

HYPOTHESIS/OBJECTIVES

To develop and internally validate a prediction tool for dogs receiving a diagnosis of Cushing's syndrome using primary-care electronic health records.

ANIMALS

Three hundred and ninety-eight dogs diagnosed with Cushing's syndrome and 541 noncase dogs, tested for but not diagnosed with Cushing's syndrome, from a cohort of 905 544 dogs attending VetCompass participating practices.

METHODS

A cross-sectional study design was performed. A prediction model was developed using multivariable binary logistic regression taking the demography, presenting clinical signs and some routine laboratory results into consideration. Predictive performance of each model was assessed and internally validated through bootstrap resampling. A novel clinical prediction tool was developed from the final model.

RESULTS

The final model included predictor variables sex, age, breed, polydipsia, vomiting, potbelly/hepatomegaly, alopecia, pruritus, alkaline phosphatase, and urine specific gravity. The model demonstrated good discrimination (area under the receiver operating curve [AUROC] = 0.78 [95% CI = 0.75-0.81]; optimism-adjusted AUROC = 0.76) and calibration (C-slope = 0.86). A tool was developed from the model which calculates the predicted likelihood of a dog having Cushing's syndrome from 0% (score = -13) to 96% (score = 10).

CONCLUSIONS AND CLINICAL IMPORTANCE

A tool to predict a diagnosis of Cushing's syndrome at the point of first suspicion in dogs was developed, with good predictive performance. This tool can be used in practice to support decision-making and increase confidence in diagnosis.

Vestibular disease in dogs under UK primary veterinary care: Epidemiology and clinical management

BACKGROUND

Vestibular disease (VD), central or peripheral, can be a dramatic primary-care presentation. Current literature describes mostly dogs examined in referral centers.

HYPOTHESIS/OBJECTIVES

Describe the prevalence, presentation, clinical management, and outcomes of VD in dogs under primary veterinary care at UK practices participating in VetCompass.

ANIMALS

Seven hundred and fifty-nine vestibular cases identified out of 905 544 study dogs.

METHODS

Retrospective cohort study. Potential VD cases clinically examined during 2016 were verified by reviewing clinical records for signalment, presenting clinical signs, treatments, and outcomes. Multivariable logistic regression was used to evaluate factors associated with VD.

RESULTS

The overall prevalence of VD was 8 per 10 000 dogs (95% CI = 7-9). Median age at first diagnosis was 12.68 years (interquartile range [IQR], 11.28-14.64). Compared with crossbreeds, breeds with the highest odds of VD diagnosis included French Bulldogs (odds ratio [OR] = 9.25, 95% CI = 4.81-17.76, P < .001), Bulldogs (OR = 6.53, 95% CI = 2.66-16.15, P < .001), King Charles Spaniels (OR = 4.96, 95% CI = 2.52-9.78, P < .001), Cavalier King Charles Spaniels (OR = 3.56, 95% CI = 2.50-5.06, P < .001), and Springer Spaniels (OR = 3.37, 95% CI = 2.52-4.52, P < .001). The most common presenting signs were head tilt (69.8%), nystagmus (68.1%), and ataxia (64.5%). The most frequently used treatments were antiemetics (43.2%), systemic glucocorticoids (33.1%), antimicrobials (25%), and propentofylline (23.25%). There were 3.6% of cases referred. Improvement was recorded in 41.8% cases after a median of 4 days (IQR, 2-10.25).

CONCLUSIONS

Our study identifies strong breed predispositions for VD. The low referral rates suggest that primary-care data sources offer more generalizable information for benchmarking to help clinicians review their own clinical activities.

Side Effects to Systemic Glucocorticoid Therapy in Dogs Under Primary Veterinary Care in the UK

Objectives: Systemic glucocorticoids are widely used in companion animals. This study aimed to estimate the frequency, describe the characteristics and to evaluate risk factors for common side effects to systemic glucocorticoid therapy in dogs under primary veterinary care in the UK.

Methods: A cohort study using VetCompass™ data from 455,557 dogs under primary veterinary care during 2013 estimated the frequency of side effects to systemic glucocorticoid therapy occurring within 31 days of therapy. Risk factors for the most common side effects, polyuria and polydipsia (PUPD), were evaluated using multivariable logistic regression modeling (P < 0.05).

Results: During 2013, 28,472 study dogs received systemic glucocorticoids (6.2%, 95% CI 6.2–6.3). Review of the records of 3,000 randomly selected treated dogs identified 148 (4.9%, 95% CI 4.2–5.7%) dogs with at least one side effect recorded within 31 days of therapy. The most frequent side effects were polydipsia (39.2% of total presenting signs), polyuria (28.4%), vomiting (16.2%) and diarrhea (14.9%), dogs receiving only oral systemic glucocorticoids (odds ratio, OR: 3.72) and dogs receiving both oral and injectable systemic glucocorticoid (OR: 10.71) had increased odds of PUPD compared with dogs receiving only injectable systemic glucocorticoid. Focusing on the active substance used, treatment with prednisolone tablets only (OR: 3.53) and treatment with both prednisolone tablets and injectable dexamethasone sodium phosphate (OR: 7.62) showed increased odds of PUPD compared to treatment with injectable dexamethasone sodium phosphate only.

Brief: These results can assist veterinarians to optimize therapeutic selection for reduced side effect, to inform owners on common side effects, and help protect the welfare of pets and their owners.

Prevalence and risk factors associated with systemic hypertension in dogs with spontaneous hyperadrenocorticism

Background

Systemic hypertension (SH) is common in dogs with hyperadrenocorticism (HAC) however there are not many studies assessing its prevalence and risk factors.

Objectives

To determine the prevalence and severity of SH in dogs with HAC and its association with clinical and laboratory findings to identify potential risk factors.

Animals

Sixty‐six client owned dogs with spontaneous HAC.

Methods

Retrospective cross‐sectional study. Medical records of dogs with HAC were reviewed. Systolic blood pressure (SBP) was measured using Doppler ultrasonography. Clinical signs, physical examination findings and clinicopathologic data (CBC, serum biochemistry and electrolytes, urinalysis and urinary culture, and adrenal function tests) were reviewed for analysis.

Results

Prevalence of SH (≥150 mm Hg) was 82% (54/66) and prevalence of severe SH (≥180 mm Hg) was 46% (30/66). All dogs with thrombocytosis had SH (P = .002), and a platelet count ≥438 × 10³/μL was 100% specific and 61.1% sensitive to predict SH (AUC = .802, P = .001). Median potassium levels were lower in hypertensive dogs (4.1 mEq/L, range 3.1‐5.4 mEq/L) than in normotensive ones (4.5 mEq/L, range 4.0‐5.0 mEq/L) (P = .007). Dogs with UPC ≥ 0.5 had higher median SBP than those without proteinuria (P = .03). Dogs with concurrent diabetes mellitus seemed to have a reduced risk of SH (OR = .118, 95%CI = .022‐.626, P = .02).

Conclusions and Clinical Importance

Systemic hypertension is common in dogs with HAC and is frequently severe. Blood pressure should be routinely assessed in these dogs, especially if thrombocytosis, proteinuria or low potassium concentrations are present.

Epidemiology and clinical management of elbow joint disease in dogs under primary veterinary care in the UK

Background

Conditions affecting the elbow joint are a common cause of lameness in dogs. Primary-care veterinary clinical data are now recognised as a valuable research resource. Using data from the VetCompass Programme, this study aimed to report the frequency and risk factors for elbow joint disease in dogs under primary veterinary care in the UK and describe clinical management.

Results

From 455,069 dogs under veterinary care, the one-year period prevalence for elbow joint disease diagnosis was 0.56% (95% CI: 0.53-0.60). Of 616 incident cases, the most common specific variants of elbow joint disease were osteoarthritis (n = 468, 75.97%), elbow dysplasia (190, 30.84%) and traumatic (41, 6.66%). The most common signs described by the owners were lameness (n = 466, 75.65%), difficulty exercising (123, 19.97%) and pain (86, 13.96%). The most common findings recorded on veterinary examination were pain (n = 283, 45.94%), lameness (278, 45.13%) and reduced range of movement (243, 39.45%). Common medications used included non-steroidal anti-inflammatory drugs (n = 544, 88.31%), tramadol (121, 19.64%) and disease modifying agents (118, 19.16%). Of 109 deaths involving euthanasia with information available from the 616 incident cases, elbow joint disease contributed to the decision to euthanase in 45 (41.28%) dogs.Five breeds showed increased odds of elbow joint disease compared with crossbred dogs: Rottweiler (OR: 6.16, 95% CI 3.89-9.75), Labrador Retriever (OR: 5.94, 95% CI 4.65-7.60), German Shepherd Dog (OR: 4.13, 95% CI 2.88-5.93), Golden Retriever (OR: 3.11, 95% CI 1.93-5.00) and English Springer Spaniel (OR: 2.00, 95% CI 1.26-3.18). Additional risk factors included having an adult bodyweight that was equal or higher than their breed/sex mean, advancing age, being male, being neutered, being insured and larger bodyweight.

Conclusions

Elbow joint disease is a relatively common diagnosis in dogs and has a high welfare impact as evidenced by the high proportion of cases recorded with pain, lameness and analgesic therapy. There are strong breed predispositions, in particular for large breed dogs. These findings present a clear case for improved breeding programmes to reduce the burden of elbow joint disease.

Development and evaluation of a health-related quality-of-life tool for dogs with Cushing's syndrome

Background

Clinical signs and consequences of Cushing's syndrome are likely to impact upon a dog's life. Quantification of this impact on a dog's health‐related quality‐of‐life (HRQoL) could contribute to optimized disease management.

Hypothesis/objectives

To develop a novel HRQoL tool to aid assessment of dogs with Cushing's syndrome and to evaluate factors that impact upon dogs living with this disease.

Animals

Two hundred and ten dogs with Cushing's syndrome and 617 dogs without Cushing's syndrome.

Methods

Cross‐sectional study design. Dog owners answered questions relating to the HRQoL of their dogs which were refined to develop the final tool. The tool was analyzed for reliability, validity, and interpretability, including Cronbach's alpha and principal components analysis. Factors impacting upon the HRQoL of dogs with Cushing's syndrome were assessed using appropriate nonparametric tests.

Results

The tool was refined from 32 questions to 19 and showed good internal consistency (α = .83). Owners rated questions related to “owner impact” as more important and those related to demeanor as less important. There was a positive correlation between the tool score of dogs with Cushing's syndrome and owner's assessment of their dog's quality‐of‐life (r = .41, P < .001). Dogs currently on treatment with trilostane had a statistically better HRQoL (.33, interquartile range [IQR] .23–.44) than those not receiving trilostane (.36, IQR .33–.54, P = .04).

Conclusions and Clinical Importance

The developed tool quantifies the HRQoL of dogs with Cushing's syndrome and could assist clinicians in the clinical assessment of dogs with Cushing's syndrome.

Survival analysis of 219 dogs with hyperadrenocorticism attending primary care practice in England

BACKGROUND

Hyperadrenocorticism is an endocrine disease routinely encountered within primary care practice; however, few studies evaluating survival beyond diagnosis have studied this population.

METHODS

This retrospective cohort study analysed the electronic patient records of 219 cases of hyperadrenocorticism from a sample of dogs attending primary care practices in England. Kaplan-Meier plots examined the cumulative survival and Cox proportional hazard regression modelling identified factors associated with the hazard of all-cause mortality.

RESULTS

In the analysis, 179/219 (81.7 per cent) hyperadrenocorticism cases died during the study period with a median survival time from first diagnosis of 510 days (95% CI 412 to 618 days). Trilostane was used in 94.1 per cent of cases and differentiation between pituitary-dependent and adrenal-dependent disease was made in 20.1 per cent of cases. In the multivariable analysis, dogs weighing greater than or equal to 15 kg (HR 1.51, 95% CI 1.06 to 2.15, P=0.023) and those diagnosed greater than or equal to 13 years of age (HR 3.74, 95% CI 2.29 to 6.09, P<0.001) had increased hazards of all-cause mortality. Dogs that had their initial trilostane dose increased had a favourable prognosis (HR 0.49, 95% CI 0.32 to 0.76, P=0.015).

CONCLUSION

This study shows that survival from diagnosis of hyperadrenocorticism appears fair for many dogs and provides primary care practitioners with relatable benchmark prognostic figures.

Molecular markers of prognosis in canine cortisol-secreting adrenocortical tumours

Hypercortisolism is caused by a cortisol‐secreting adrenocortical tumour (ACT) in approximately 15%‐20% of cases in dogs. Little is known about which molecular markers are associated with malignant behaviour of canine ACTs. The objective of this study was to identify molecular markers of prognosis, which could be useful to refine prognostic prediction and to identify potential treatment targets. Cortisol‐secreting ACTs were included from 40 dogs, of which follow‐up information was available. The ACTs were classified as low risk of recurrence tumours (LRT; n = 14) or moderate‐high risk of recurrence tumours (MHRT; n = 26), based on the novel histopathological Utrecht score. Normal adrenals (NAs) were included from 11 healthy dogs as reference material. The mRNA expression of 14 candidate genes was analysed in the 40 ACTs and in 11 NAs with quantitative RT‐PCR. The genes' expression levels were statistically compared between NAs, LRTs and MHRTs. Univariate and multivariate analyses were performed to determine the association of the genes' expression levels with survival. Seven genes were differentially expressed between NAs and ACTs, of which pituitary tumour‐transforming gene‐1 (PTTG1) and topoisomerase II alpha (TOP2A) were also differentially expressed between LRTs and MHRTs. In survival analyses, high expression levels of Steroidogenic factor‐1 (SF‐1), PTTG1 and TOP2A were significantly associated with poor survival. In conclusion, we have identified several genes that are part of the molecular signature of malignancy in canine ACTs. These findings can be used to refine prognostic prediction, but also offer insights for future studies on druggable targets.

Diagnosis of spontaneous hyperadrenocorticism in dogs. Part 1: Pathophysiology, aetiology, clinical and clinicopathological features

Hyperadrenocorticism is a relatively common endocrine disorder in dogs. It occurs as a result of a functional pituitary or adrenal tumour, although other causes have been rarely reported. Canine hyperadrenocorticism has been extensively described but diagnosing this disease remains challenging. Few studies have investigated the clinical and clinicopathological features helpful in differentiating dogs with hyperadrenocorticism from dogs in which the disease is suspected but eventually excluded. Ultimately the diagnosis is based on a combination of multiple pieces of information emanating from the signalment, history, clinical findings, and a variety of diagnostic tests. The first part of this review aims to critically appraise the available data on epidemiology, clinical and laboratory features of naturally occurring canine hyperadrenocorticism.

Health-related welfare prioritisation of canine disorders using electronic health records in primary care practice in the UK

Background

Evidence-based comparison of the disorder-specific welfare burdens of major canine conditions could better inform targeting of stakeholder resources, to maximise improvement of health-related welfare in UK dogs. Population-level disease related welfare impact offers a quantitative, welfare-centred framework for objective disorder prioritisation, but practical applications have been limited to date due to sparse reliable evidence on disorder-specific prevalence, severity and duration across the canine disease spectrum. The VetCompass™ Programme collects de-identified electronic health record data from dogs attending primary-care clinics UK-wide, and is well placed to fill these information gaps.

Results

The eight common, breed-related conditions assessed were anal sac disorder, conjunctivitis, dental disease, dermatitis, overweight/obese, lipoma, osteoarthritis and otitis externa. Annual period prevalence estimates (based on confirming 250 cases from total potential cases identified from denominator population of 455, 557 dogs) were highest for dental disorder (9.6%), overweight/obese (5.7%) and anal sac disorder (4.5%). Dental disorder (76% of study year), osteoarthritis (82%), and overweight/obese (70%) had highest annual duration scores. Osteoarthritis (scoring 13/21), otitis externa (11/21) and dermatitis demonstrated (10/21) highest overall severity scores. Dental disorder (2.47/3.00 summative score), osteoarthritis (2.24/3.00) and overweight/obese (1.67/3.00) had highest VetCompass Welfare Impact scores overall.

Discussion

Of the eight common, breed-related disorders assessed, dental disorder, osteoarthritis and overweight/obese demonstrated particular welfare impact, based on combinations of high prevalence, duration and severity. Future work could extend this methodology to cover a wider range of disorders.

Conclusions

Dental disorders, osteoarthritis and overweight/obese have emerged as priority areas for health-related welfare improvement in the UK dog population. This study demonstrated applicability of a standardised methodology to assess the relative health-related welfare impact across a range of canine disorders using VetCompass clinical data.

Clinical and Clinicopathological Features in Dogs with Uncomplicated Spontaneous Hyperadrenocorticism Diagnosed in Primary Care Practice (2013-2014)

The objective of this study was to report clinical and clinicopathological abnormalities in canine spontaneous hyperadrenocorticism (HAC) and assess the relationship between patient size and those findings. A questionnaire was made available to primary care veterinarians to gather information on cases diagnosed with canine spontaneous HAC. Inclusion criteria were an adrenocorticotropic stimulation test and/or low-dose dexamethasone suppression test consistent with HAC. Exclusion criteria included concurrent systemic diseases, any clinical sign (CS) not typically associated with HAC, a urinary corticoid:creatinine ratio within reference interval, administration of steroids during the 3 mo before diagnosis, treatment with any drug causing CSs of HAC, and ongoing treatment for canine spontaneous HAC. Sixty-two cases were identified. The prevalences of various CSs were similar to those historically reported. No association between the patient weight and CSs was identified. The platelet count was negatively correlated to the weight (P = .005, r² = 0.3). Alanine aminotransferase (P = .016, r² = 0.17) and alkaline phosphatase (P = .05, r² = 0.0014) activities were positively correlated to the CS ratio. In this group of dogs, CSs were not significantly different between dogs ≤20 kg and dogs >20 kg. The prevalences of various clinical findings appeared to be similar to those historically reported. Dogs with more CSs tended to have higher alanine aminotransferase and alkaline phosphatase activities.

Detecting false-positive disease references in veterinary clinical notes without manual annotations

Clinicians often include references to diseases in clinical notes, which have not been diagnosed in their patients. For some diseases terms, the majority of disease references written in the patient notes may not refer to true disease diagnosis. These references occur because clinicians often use their clinical notes to speculate about disease existence (differential diagnosis) or to state that the disease has been ruled out. To train classifiers for disambiguating disease references, previous researchers built training sets by manually annotating sentences. We show how to create very large training sets without the need for manual annotation. We obtain state-of- the-art classification performance with a bidirectional long short-term memory model trained to distinguish disease references between patients with or without the disease diagnosis in veterinary clinical notes.

Cushing's syndrome-an epidemiological study based on a canine population of 21,281 dogs

The epidemiological characteristics of spontaneous hypercortisolism (HC) were derived from 21,281 client-owned dogs selected from four private veterinary clinics and one university reference center for endocrinology. The odds ratio (OR) method was employed to investigate the risk of developing HC related to breed, gender, and sexual status. The estimated prevalence of HC in the four private clinics was 0.20% [95% confidence interval (CI), 0.13–0.27] and was significantly different compared to the university reference center (1.46%; 95% CI, 1.12–1.80). Sex, breed, and age resulted in risk factors for HC. Mean (± SD) age for dogs with HC was 9.8 (± 2.5) yr. Females had higher risk for HC compared to males (OR 1.85; 95% CI, 1.24–2.75); all neutered dogs (both males and females) had higher risk than intact dogs (OR 2.54; 95% CI, 1.72–3.73); and neutered females had higher risk compared to intact females (OR 2.61; 95% CI, 1.54–4.42). Using the mixed breed dogs as a control population (OR = 1), the risk of developing HC was significantly higher in the Standard Schnauzer (OR 58.1; p < 0.0001) and Fox Terrier (OR 20.33; p < 0.0001).

With regard to HC, this study identified an overall prevalence of 0.20%. The data support the existence of sex predisposition, with the highest risk for neutered females.

Melanocortin 2 receptor antagonists in canine pituitary-dependent hypercortisolism: in vitro studies

Canine hypercortisolism is most often caused by an ACTH-secreting pituitary adenoma (pituitary-dependent hypercortisolism; PDH). An interesting target for a selective medical treatment of PDH would be the receptor for ACTH: the melanocortin 2 receptor (MC2R). In this study we investigated whether two peptide compounds, BIM-22776 (#776) and BIM-22A299 (#299), are effective MC2R antagonists in vitro. Their effects on cortisol production and mRNA expression of steroidogenic enzymes, MC2R and melanocortin 2 receptor accessory protein (MRAP) were evaluated in primary adrenocortical cell cultures (n = 8) of normal canine adrenal glands. Cortisol production stimulated by 50 nM ACTH was dose-dependently inhibited by #299 (inhibition 90.7 ± 2.3% at 5 μM) and by #776 (inhibition 38.0 ± 5.2% at 5 μM). The ACTH-stimulated mRNA expression of steroidogenic enzymes, MC2R and MRAP was significantly inhibited by both compounds, but most potently by #299. These results indicate that canine primary cell culture is a valuable in vitro system to test MC2R antagonists, and that these compounds, but especially #299, are effective MC2R antagonists in vitro. To determine its efficacy in vivo, further studies are warranted. Antagonism of the MC2R is a promising potential treatment approach in canine PDH.

Canine hyperadrenocorticism associations with signalment, selected comorbidities and mortality within North American veterinary teaching hospitals

OBJECTIVE

To describe a large population of dogs with a diagnosis of hyperadrenocorticism at the time of death in North American veterinary teaching hospitals, and to identify comorbid conditions associated with hyperadrenocorticism.

MATERIALS AND METHODS

Retrospective cohort study of 1519 dogs with hyperadrenocorticism from a population of 70,574 dogs reported to the Veterinary Medical Database. Signalment, presence or absence of hyperadrenocorticism, aetiology of hyperadrenocorticism (if described), frequency of select comorbidities and causes of death were evaluated in dogs with and without hyperadrenocorticism.

RESULTS

Hyperadrenocorticism was more frequent in females. Neutering was associated with a minor, but significant, increase in the odds of hyperadrenocorticism. Hyperadrenocorticism was the presumed cause of death of 393 (25∙9%) of affected dogs. When aetiology was specified (527 dogs, corresponding to 34∙7% of the cases), pituitary-dependent hyperadrenocorticism [387 (73∙4%) out of 527 dogs] was more common than functional adrenocortical tumour [136 (25∙8%) out of 527 dogs). Hyperadrenocorticism was over-represented in certain expected (miniature poodle, dachshund) and unexpected (Irish setter, bassett hound) breeds compared with the population at large. Of the select comorbidities investigated, dogs with hyperadrenocorticism were at increased risk for concurrent diabetes mellitus, urinary tract infection, urolithiasis, hypertension, gall bladder mucocoele and thromboembolic disease compared with dogs without hyperadrenocorticism.

CLINICAL SIGNIFICANCE

Hyperadrenocorticism is significantly associated with certain comorbid conditions but is not a major cause of mortality in affected dogs. Documented patterns now provide targets for prospective clinical research.

Urinary incontinence in male dogs under primary veterinary care in England: prevalence and risk factors

OBJECTIVE

To estimate prevalence and identify demographic risk factors for urinary incontinence in male dogs.

METHODS AND METHODS

The study population included all dogs within the VetCompass database from September 1, 2009 to July 7, 2013. Electronic patient records were searched for urinary incontinence cases; demographic and clinical information were extracted and analysed.

RESULTS

Of 109,428 male dogs attending 119 clinics in England, there were an estimated 1027 dogs diagnosed with urinary incontinence, giving a prevalence of 0.94% (95% confidence interval: 0.88 to 1.00). Breeds with highest odds of incontinence in male dogs (compared with mixed breed dogs) included the bull mastiff (odds ratio: 17.21, 95% confidence interval: 6.65 to 44.56, case=5, non-case=314, P<0.001), Irish red setter (odds ratio: 12.79, 95% confidence interval: 4.83 to 33.84, case=5, non-case=142, P<0.001), fox terrier (odds ratio: 9.60, 95% confidence interval: 3.68 to 25.05, case=5, non-case=176, P < 0.001), bulldog (odds ratio: 5.72, 95% confidence interval: 2.24 to 14.59, case=5, non-case=929, P<0.001) and boxer (odds ratio: 3.65, 95% confidence interval: 1.84 to 7.25, case=10, non-case=1470, P<0.001). Increased odds of urinary incontinence were associated with greater age (age 9 to 12 years, odds ratio: 10.46, 95% confidence interval: 6.59 to 16.62, n=12,348, P<0.001) and being insured (odds ratio: 1.96, 95% confidence interval: 1.53 to 2.51, n=26,202, P<0.001). There was no association with castration or bodyweight using multi-variable analysis.

CLINICAL SIGNIFICANCE

The overall prevalence of urinary incontinence in male dogs is approximately 1%, which may be higher than expected given the sparsity of reports describing this problem. In contrast to bitches, neutering and bodyweight were not associated with greater odds of urinary incontinence, which is important when giving neutering advice.

Abiraterone Acetate for Cushing Syndrome: Study in a Canine Primary Adrenocortical Cell Culture Model

Abiraterone acetate (AA) is a potent inhibitor of steroidogenic enzyme 17α-hydroxylase/17,20-lyase (CYP17A1). AA is approved for the treatment of prostate cancer but could also be used to treat patients with Cushing syndrome (CS). Similar to humans, canine glucocorticoid synthesis requires CYP17A1, providing a useful animal model. The objective of this study was to preclinically investigate the effect of AA on adrenocortical hormone production, cell viability, and mRNA expression of steroidogenic enzymes in canine primary adrenocortical cell cultures (n = 9) from the adrenal glands of nine healthy dogs. The cells were incubated with AA (0.125 nM to 10 μM) for 72 hours under basal conditions and with 100 nM ACTH(1-24). Adrenocortical hormone concentrations were measured in culture medium using liquid chromatography-mass spectrometry, RNA was isolated from cells for subsequent real-time quantitative PCR analysis, and cell viability was assessed with an alamarBlue™ assay. AA reduced cortisol (IC50, 21.4 ± 4.6 nM) without affecting aldosterone under basal and ACTH-stimulated conditions. AA increased progesterone under basal and ACTH-stimulated conditions but reduced corticosterone under basal conditions, suggesting concurrent inhibition of 21-hydroxylation. AA did not affect the mRNA expression of steroidogenic enzymes and did not inhibit cell viability. In summary, primary canine adrenocortical cell culture is a useful model system for drug testing. For the treatment of CS, AA may to be superior to other steroidogenesis inhibitors due to its low toxicity. For future in vivo studies, dogs with endogenous CS may provide a useful animal model.