Causes of anaemia other than acute blood loss and their clinical significance in dogs.

OBJECTIVES: To identify the causes of anaemia, other than acute blood loss, in dogs and to determine whether severity of anaemia provides clues to the diagnosis. METHODS: The veterinary medical database of the Veterinary Campus Hospital, Lyon was searched. Dogs with anaemia (packed cell volume <37%) were included and assigned to different disease groups. Dogs with acute blood loss were excluded. The case records were examined for weakness at presentation, the severity and regeneration of anaemia and the final diagnosis including tumour type if applicable. RESULTS: The case records of 456 dogs with low packed cell volume were included. Cancer-related anaemia and anaemia of inflammatory disease accounted for 33·1 and 28·5% of cases, respectively. Most dogs with cancer-related anaemia had solid tumours (73%). The prevalence of immune-mediated anaemia increased with severity of anaemia (5·3, 15·5, 41·2 and 56·2% for mild, moderate, severe and very severe anaemia, respectively), whereas the prevalence of anaemia of inflammatory disease decreased (36·7, 22·5, 2·9 and 0% for mild, moderate, severe and very severe anaemia, respectively). CLINICAL SIGNIFICANCE: Anaemia of inflammatory disease and cancer-related anaemia were the most frequently identified causes of anaemia in dogs. The percentage of dogs with immune-mediated anaemia increased with anaemia severity, whereas the percentage of dogs with anaemia of inflammatory disease decreased with anaemia severity. Thus, severity of anaemia may provide clues to the diagnosis.

Use of computed tomography adrenal gland measurement for differentiating ACTH dependence from ACTH independence in 64 dogs with hyperadenocorticism.

BACKGROUND: The measurement of adrenal gland size on computed tomography (CT) scan has been proposed for the etiological diagnosis of hyperadrenocorticism (HAC) in dogs. Symmetric adrenal glands are considered to provide evidence for ACTH-dependent hyperadrenocorticism (ADHAC), whereas asymmetry suggests ACTH-independent hyperadrenocorticism (AIHAC). However, there are currently no validated criteria for such differentiation. OBJECTIVE: The aim of this retrospective study was to compare various adrenal CT scan measurements and the derived ratios in ADHAC and AIHAC cases, and to validate criteria for distinguishing between these conditions in a large cohort of dogs. ANIMALS: Sixty-four dogs with HAC (46 ADHAC, 18 AIHAC). METHODS: Dogs with confirmed HAC and unequivocal characterization of its origin were included. Linear measurements of adrenal glands were made on both cross-sectional and reformatted images. RESULTS: An overlap was systematically observed between the AIHAC and ADHAC groups for all measurements tested. Overlaps also were observed for ratios tested. For the maximum adrenal diameter ratio derived from reformatted images (rADR), only 1/18 AIHAC dogs had a rADR within the range for ADHAC. For a threshold of 2.08, the 95% confidence intervals for estimated sensitivity and specificity extended from 0.815 to 1.000 and from 0.885 to 0.999, respectively, for AIHAC diagnosis. CONCLUSION AND CLINICAL IMPORTANCE: Measurements from cross-sectional or reformatted CT scans are of little use for determining the origin of HAC. However, rADR appears to distinguish accurately between ADHAC and AIHAC, with a rADR > 2.08 highly suggestive of AIHAC.

Ultrasonography criteria for differentiating ACTH dependency from ACTH independency in 47 dogs with hyperadrenocorticism and equivocal adrenal asymmetry.

BACKGROUND: Adrenal ultrasonography (US) in dogs with hyperadrenocorticism (HAC) is commonly used to distinguish adrenocorticotropic hormone (ACTH)-independent (AIHAC) and ACTH-dependent hyperadrenocorticism (ADHAC). To date, no cut-off values for defining adrenal atrophy in cases of adrenal asymmetry have been determined. Given that asymmetrical hyperplasia is sometimes observed in ADHAC, adrenal asymmetry without ultrasonographic proof of adrenocortical tumor such as vascular invasion or metastasis can be equivocal. OBJECTIVE: The purpose of this study was to compare adrenal US findings between cases of ADHAC and AIHAC in dogs with equivocal adrenal asymmetry (EAA), and to identify useful criteria for their distinction. ANIMALS: Forty dogs with EAA were included. METHODS: Ultrasound reports of HAC dogs with adrenal asymmetry without obvious vascular invasion or metastases were reviewed. Dogs were classified as cases of ADHAC (n = 28) or AIHAC (n = 19), determined by plasma ACTH concentration. The thickness, shape, and echogenicity of both adrenal glands and presence of adjacent vascular compression were compared between AIHAC and ADHAC groups. RESULTS: The maximal dorsoventral thickness of the smaller gland (SDV) ranged from 2.0 to 5.0 mm in AIHAC and from 5.0 to 15.0 mm in ADHAC. The 95% confidence intervals for estimated sensitivity and specificity of a SDV cut-off set at 5.0 mm in the diagnosis of AIHAC were 82-100 and 82-99%, respectively. Other tested US criteria were found to overlap extensively between the 2 groups, precluding their usefulness for distinction. CONCLUSION AND CLINICAL IMPORTANCE: In EAA cases, an SDV ≤5.0 mm is an appropriate cut-off for AIHAC ultrasonographic diagnosis.

Accuracy of an adrenocorticotropic hormone (ACTH) immunoluminometric assay for differentiating ACTH-dependent from ACTH-independent hyperadrenocorticism in dogs.

BACKGROUND: Adrenocorticotropic hormone (ACTH) determination has been used for 30 years to distinguish ACTH-dependent hyperadrenocorticism (ADHAC) from ACTH-independent hyperadrenocorticism (AIHAC) in dogs. However, the few studies that have evaluated its diagnostic accuracy, based in the majority of cases on older assays, have been associated with systematic, but highly variable proportions of misclassified or unclassified cases. OBJECTIVE: The purpose of the present study is to evaluate the accuracy of a validated ACTH immunoluminometric assay (ILMA) for differentiating between ADHAC and AIHAC. ANIMALS: One hundred and nine dogs with hyperadrenocorticism were included: 91 with ADHAC and 18 with AIHAC. METHODS: Retrospective study. Dogs displaying feedback inhibition after the dexamethasone suppression test, adrenal symmetry, or both were considered to have ADHAC. AIHAC was demonstrated by adrenal tumor histology. For each group, ACTH determination by ILMA was reviewed. RESULTS: In the ADHAC group, plasma ACTH measurements ranged between 6 and 1250 pg/mL (median, 30 pg/mL). In the AIHAC group, all ACTH concentrations were below the lower quantification limit of the assay (<5 pg/mL). The 95% confidence interval was 85-100% for sensitivity and 97-100% for specificity in AIHAC diagnosis. CONCLUSION AND CLINICAL IMPORTANCE: No overlap in ACTH concentrations was observed between dogs with ADHAC and dogs with AIHAC. The use of a new technique with high analytical sensitivity made it possible to use a low threshold (5 pg/mL), avoiding the misclassification of some ADHAC cases with low, but quantifiable concentrations of ACTH. The assessment of ACTH concentrations by ILMA is an accurate tool for differentiating between ADHAC and AIHAC.