Comparison of methods to monitor dogs with hypercortisolism treated with trilostane

Trilostane: Beyond Cushing's Syndrome

Trilostane is a drug able to block the synthesis of progesterone from pregnenolone, dependent on the enzyme 3β-hydroxysteroid dehydrogenase/Δ5-4 isomerase. As a consequence of this effect, it is used to treat endocrinological diseases such as Cushing's syndrome, especially in dogs. Because of the modulatory effects of trilostane on the hypothalamic-pituitary-adrenal axis, trilostane administration causes an increase in brain levels of neurosteroids with anticonvulsant properties, as in the case of allopregnanolone. Allopregnanolone is also of interest in curing depression, suggesting that trilostane might represent a tool to address neurological and psychiatric disorders. In this review, we investigated the historical development of this drug and its current use, mechanisms, and possible developments. By searching the literature from 1978 to 2025, we identified 101 papers describing studies with trilostane. Precisely, 55 were about dogs and trilostane, 3 were on cats, and 23 were with other animals. Some studies (15) were also designed with human patients. The main disease treatment with trilostane was hyperadrenocorticism. However, we also found two preclinical papers on trilostane's potential use in psychiatric diseases and three on trilostane's potential use in neurological disorders. Moreover, few clinical and preclinical studies suggested the involvement of neurosteroids modulated by trilostane in different neurological disorders, thus opening a possible new perspective for the use of this drug.

Transsphenoidal Surgery for Pituitary Tumors

Transsphenoidal surgery for the treatment of pituitary masses in cats and dogs has become a more established treatment over the last 2 decades. Although expert centers and surgeons that provide this service remain limited, the patient population presented for pituitary surgery increases with wider availability of advanced imaging, together with more challenging cases. In this review, the current state of hypophysectomy is described with future challenges and opportunities.

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.

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.

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.

Increases in serum carbonylated protein levels of dogs with hypercortisolism

Protein carbonylation is an irreversible and degenerative modification that can be used to evaluate oxidative stress caused by glucocorticoids. In this study, we focused on protein carbonylation in dogs with hypercortisolism (HC). Sera samples were collected from 14 dogs diagnosed with HC and treated with trilostane, 12 dogs with inflammatory diseases (disease control group), and eight clinically healthy dogs. When the carbonylated protein levels were detected by the immunoblot analysis, one band of approximately 40 kDa was predominantly increased in the dogs with HC. The band was identified as haptoglobin using the liquid chromatography tandem mass spectrometry method. Furthermore, haptoglobin immune reactivity was higher in the dogs with HC. Although the average protein carbonylation level of the HC group was not significantly different from that of the other groups, the carbonylation level was significantly higher for the poorly controlled HC cases than for the well-controlled HC group. Additionally, the primary culture of canine hepatocytes was used to clarify the direct effect of glucocorticoids on protein carbonylation in dog livers. Both the carbonylated protein and haptoglobin clearly increased after 72 h. These findings suggest that haptoglobin and its carbonylated form are increased with canine HC, and that the protein carbonylation ratio and/or haptoglobin level could be related to disease management. These factors could be useful as biomarkers for an oxidative stress reaction, at least in the liver, and for treatment monitoring of HC.

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.

Investigation of the urine cortisol to creatinine ratio for the diagnosis of hypoadrenocorticism in dogs

OBJECTIVE

To evaluate the urine cortisol-to-creatinine ratio (UCCR) for the diagnosis of hypoadrenocorticism (HA) in dogs and to determine whether the method of urine cortisol measurement affects results.

ANIMALS

41 dogs with naturally occurring HA and 107 dogs with nonadrenal illness.

PROCEDURES

Urine samples were prospectively collected from dogs undergoing testing for HA. Urine cortisol concentrations were measured at a veterinary diagnostic laboratory using either a radioimmunoassay (RIA) or a chemiluminescent immunoassay (CLIA). Receiver operating characteristic (ROC) curves were constructed to assess UCCR performance by both methods for HA diagnosis. Sensitivities, specificities, accuracies, and predictive values were calculated for various cutpoints.

RESULTS

The areas under the ROC curves for UCCR diagnosis of HA were 0.99 (95% CI, 0.98 to 1.00) and 1.00 (95% CI, 1.00 to 1.00) when urine cortisol was determined by RIA and CLIA, respectively. An RIA UCCR of ≤ 2 was 97.2% sensitive, 93.6% specific, and 94.7% accurate for HA diagnosis, whereas a CLIA UCCR of ≤ 10 was 100% sensitive, specific, and accurate. An RIA UCCR > 4 and a CLIA UCCR of > 10 had negative predictive values of 100%.

CLINICAL RELEVANCE

The UCCR was an accurate diagnostic test for HA in this study population, although equivocal results are possible. Case characteristics, method of cortisol measurement, and laboratory-specific cutpoints must be considered when interpreting results.

Metabolomic Abnormalities in Serum from Untreated and Treated Dogs with Hyper- and Hypoadrenocorticism

The adrenal glands play a major role in metabolic processes, and both excess and insufficient serum cortisol concentrations can lead to serious metabolic consequences. Hyper- and hypoadrenocorticism represent a diagnostic and therapeutic challenge. Serum samples from dogs with untreated hyperadrenocorticism (n = 27), hyperadrenocorticism undergoing treatment (n = 28), as well as with untreated (n = 35) and treated hypoadrenocorticism (n = 23) were analyzed and compared to apparently healthy dogs (n = 40). A validated targeted proton nuclear magnetic resonance (¹H NMR) platform was used to quantify 123 parameters. Principal component analysis separated the untreated endocrinopathies. The serum samples of dogs with untreated endocrinopathies showed various metabolic abnormalities with often contrasting results particularly in serum concentrations of fatty acids, and high- and low-density lipoproteins and their constituents, which were predominantly increased in hyperadrenocorticism and decreased in hypoadrenocorticism, while amino acid concentrations changed in various directions. Many observed serum metabolic abnormalities tended to normalize with medical treatment, but normalization was incomplete when compared to levels in apparently healthy dogs. Application of machine learning models based on the metabolomics data showed good classification, with misclassifications primarily observed in treated groups. Characterization of metabolic changes enhances our understanding of these endocrinopathies. Further assessment of the recognized incomplete reversal of metabolic alterations during medical treatment may improve disease management.

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.