Urinary corticoids in the diagnosis of canine hyperadrenocorticism

In 20 healthy experimental dogs the 24 hour urinary corticoid excretion as measured by cortisol radioimmunoassay on two consecutive days varied from 0.5 to 3.3 nmol/kg/24 hours and from 0.3 to 3.6 nmol/kg/24 hours. In 20 dogs with otherwise proven spontaneous hyperadrenocorticism these values varied from 4.4 to 35.7 nmol/kg/24 hours and from 3.6 to 26.8 nmol/kg/24 hours respectively. Corticoid/creatinine ratios in morning urine samples of 28 healthy pet dogs were 1.2 to 6.9 X 10(-6). In 27 dogs with spontaneous hyperadrenocorticism all ratios exceeded the range observed in the healthy pet dogs.     

Evaluation of canine hyperadrenocorticism, using computed tomography

Abdominal computed tomography was performed in 9 dogs with hyperadrenocorticism and in 2 healthy dogs. Both adrenal glands were identified in all dogs. Computed tomography allowed accurate identification of the sites of adrenal gland dysfunction, when interpreted in combination with a biochemical diagnosis of canine hyperadrenocorticism. This accuracy permitted the retroperitoneal approach to be used for all adrenalectomies. Use of contrast medium (although not essential) was helpful in the computed tomographic identification of blood vessels, kidneys, and other abdominal organs.     

Computed tomographic adrenal gland quantification in canine adrenocorticotroph hormone-dependent hyperadrenocorticism

We conducted a retrospective study to determine whether multidetector computed tomography (CT) could be of value for adrenal gland assessment in dogs with pituitary-dependent hyperadrenocorticism. Adrenal gland attenuation and volume values of 49 dogs with hyperadrenocorticism were recorded and age, body weight, and gender were examined to determine if a relationship existed between these variables and adrenal gland morphology. There was not a statistically significant difference in mean X-ray attenuation of the left vs. right adrenal gland in normal dogs (35.3 +/- 6.1 HU), or in dogs with hyperadrenocorticism. The mean adrenal X-ray attenuation (+/- standard deviation [SD]) in dogs with microadenoma was 33.1 +/- 6.8 vs. 31.8 +/- 12.7 HU for dogs with macroadenoma, and these values were not statistically different. The mean volume of the left adrenal gland in normal dogs (0.59 +/- 0.17 cm3) was greater than that of the right adrenal gland (0.54 +/- 0.19 cm3) (P < 0.05). The mean CT volume (+/- SD) of the adrenal glands in dogs with microadenoma vs. macroadenoma were 1.60 +/- 1.25 vs. 2.88 +/- 1.60 cm3, respectively. There was no effect of age or gender on adrenal gland morphology or X-ray attenuation. The weight effect was the most important source of variation for the volume measurement in dogs with hyperadrenocorticism.     

Assessment of two tests for the diagnosis of canine hyperadrenocorticism

The low-dose dexamethasone suppression test and the urinary corticoid/creatinine ratio were assessed in 166 and 150 dogs, respectively, for their value in the diagnosis of hyperadrenocorticism. The diagnostic accuracy of the low-dose dexamethasone suppression test was 0.83, with a 95 per cent confidence interval from 0.76 to 0.88. The urinary corticoid/creatinine ratio had a diagnostic accuracy of 0.91 with a 95 per cent confidence interval from 0.85 to 0.95. The high predictive value of a negative corticoid/creatinine ratio (0.98; confidence interval 0.80 to 1.00) and the low cost of this test makes it preferable for screening purposes to the low-dose dexamethasone suppression test for which the predictive value of a negative test was calculated as 0.5g (confidence interval 0.43 to 0.73).     

The use of 17-hydroxyprogesterone in the diagnosis of canine hyperadrenocorticism

A number of dogs are seen with clinical signs consistent with hyperadrenocorticism (HAC), supporting CBC and biochemical findings, but the disease cannot be confirmed with either the ACTH stimulation test or the low-dose dexamethasone suppression test (LDDST). Therefore, another screening test is required to aid diagnosis in these atypical cases of HAC. The aim of this study was to investigate whether measuring 17-hydroxyprogesterone (OHP) concentrations could be used in this role. Plasma cortisol and OHP concentrations were measured in dogs with clinical signs suggestive of HAC before and after administration of exogenous ACTH. In dogs with HAC, plasma OHP showed an exaggerated response to ACTH stimulation. This was seen in both typical cases of HAC with a positive cortisol response to ACTH administration and in atypical cases with negative screening test results. The test can be performed on plasma already taken for a conventional ACTH stimulation test. Post-ACTH OHP concentrations decreased after treatment with mitotane or adrenalectomy. These results suggest that OHP measurements can be used as an aid to diagnose and manage canine HAC.     

Computed tomography study of implantation corridors in canine vertebrae

OBJECTIVES: To define the characteristics of optimum implantation corridors in vertebral bodies C2 to C7 and T10 to S1, using computed tomography examination. METHODS: Measurements were taken from 207 vertebrae from 35 different adult dogs. RESULTS: Implantation corridors of the cervical vertebrae are narrow. The width preserving the transverse hole is less than 2.5 mm in 68.6 per cent of the 86 vertebrae C2 to C6. Dorsal implantation corridors of the last four thoracic vertebrae are narrow, and major anatomical structures are very close to their emergence point. In 63 per cent of the 40 thoracic vertebrae, the right azygos vein is at a distance less than or equal to 1 mm from the vertebral body. The first six lumbar vertebrae have broader corridors. Furthermore, vascular structures are far from the emergence point. The last lumbar vertebra and the sacrum have a broad pedicle, which provides an alternative site for implant placement. CLINICAL SIGNIFICANCE: For the vertebrae L1 to S1, the dorsal implantation can be performed. For the cervical vertebrae, the risk of laceration of the vertebral artery is high. For the last four thoracic vertebrae, the dorsal implantation should not be used.     

Diagnosis of canine hyperadrenocorticism.

Canine hyperadrenocorticism is one of the most common endocrinopathies in dogs. Diagnosis remains difficult in some cases due to factors such as the presence of non-adrenal illness and limitations in the tests. Differentiation between the pituitary and adrenal forms is important for providing accurate prognostic information and delineating treatment options and protocols. This article reviews the tests available for diagnosis (screening) and differentiation and evaluates their advantages and disadvantages. Recommendations for testing are made.     

Familial canine pituitary-dependent hyperadrenocorticism in wirehaired Dachshunds

Canine pituitary hyperadrenocorticism (Cushing's disease) caused by neoplasia of the corticotrope cells is one of the most common endocrine diseases especially in smaller dog breeds. Cushing's disease was diagnosed in eleven wire-haired Dachshunds and for further six wire-haired Dachshunds Cushing's disease was suspected on the basis of clinical signs. A joined pedigree could be ascertained for all these 17 dogs. Eleven of these dogs were so closely related to each other, that they were summarized in four nucleus families. Two fullsiblings were examined by means of clinical, laboratory diagnostic and morphological methods. The main lesions consisted of atrophic dermatosis with alopecia, increase of activity of liver enzymes in plasma and bilateral adrenocortical hyperplasia and therefore corresponded to the typical signs of a secondary hyperadrenocorticism. A rather unusual finding was the pituitary carcinoma in one of these dogs. Similarly to human patients affected by hyperadrenocorticism, real-time PCR analysis showed a 2.9-fold increase of expression of the canine MDR1 gene in the liver of one affected wirehaired Dachshund. This study documents the first familial occurrence of pituitary-dependent hyperadrenocorticism in wirehaired Dachshunds, the overexpression of the MDR1 gene in the dog and the third case of familial hyperadrenocorticism in dogs ever described.     

Diagnostic efficacy of plasma ACTH-measurement by a chemiluminometric assay in canine hyperadrenocorticism

This retrospective study was performed to investigate the diagnostic efficacy of the chemiluminometric ACTH-measurement to differentiate between pituitary and adrenal dependent hyperadrenocorticism (HAC) in dogs. 49 dogs with pituitary HAC, 10 dogs with adrenal HAC and 1 dog with a combination of both pathologies were included. Dogs with HAC like symptoms, where HAC had been ruled out, served as controls (n = 18). All dogs with adrenal HAC, as well as 9 dogs with pituitary HAC had an ACTH concentration below the detection limit of 2.2 pmol/l (10 pg/dl) plasma. Using 2.2 pmol/l as a cut-off the sensitivity and specificity to diagnose pituitary HAC was 0.82 (95 % CI 0.686 - 0.914) and 1 (95 % CI 0.692 - 1), respectively. With the help of the chemiluminometric assay, a correct classification was possible in 85 % of patients with HAC. As an ACTH-concentration below the detection limit was found in dogs with adrenal as well as pituitary HAC, additional discriminatory tests are necessary in these cases.     

Osteopenia and other radiographic signs in canine hyperadrenocorticism

The specificity of conventional radiography in assessing canine hyperadrenocorticism was evaluated by comparing the Incidence of related radiographic findings in 24 hyperadrenocorticoid, 15 diabetic and 20 hypothyroid dogs. Hyperadrenocorticoid dogs showed significantly more perihilar bronchial mineralisation than other groups. There was no significant variation between the disease groups with respect to obesity, hepatomegaly, contour of the caudoventral hepatic margin, peripheral bronchial mineralisation or osteopenia. Adrenal mineralisation and calcinosis cutis were rare findings observed only in hyperadrenocorticoid dogs. The effect of obesity on the radiographic appearance of bone was studied using a dissected lumbar spine from a canine cadaver. An osteopenic effect could be demonstrated by superimposition of a 10 cm-thick fat block. The low specificity of almost all common signs in canine hyperadrenocorticism and the low incidence of characteristic findings demonstrate the limited potential of radiography in assessing this condition. Radiographic assessment of bone density is unreliable because of artefactual osteopenic effects of high kVp settings necessary in obese dogs.     

Computed tomography versus arthroscopy for detection of canine elbow dysplasia lesions

Objective— To describe associations between computed tomography (CT) and arthroscopy in dogs with elbow dysplasia lesions.
Study Design— Retrospective clinical study.
Sample Population— Canine elbows (n=101) investigated by CT and arthroscopy.
Methods— CT scans were reviewed for 10 predetermined CT signs and graded for osteophyte size. Surgical reports were reviewed for specific disease features and cartilage erosion grades. Associations between variables were investigated with multivariate logistic regression and correlation between osteophyte size and cartilage erosion with Spearman's rank order correlation.
Results— Medial coronoid process (MCP) fragment on CT was significantly associated with the arthroscopic identification of a displaced MCP fragment, cartilage erosion affecting the MCP, and cartilage erosion affecting the humeral condyle. Irregular radial incisure of the ulna on CT was significantly associated with the arthroscopic identification of cartilage erosion affecting the MCP. Osteophytes on CT were significantly associated with an abnormal arthroscopic examination. There was a moderately significant correlation between CT osteophyte grade and cartilage erosion grades for areas of the medial joint compartment (r_s=0.44–0.48).
Conclusion— Some CT signs are significantly associated with arthroscopic features of elbow dysplasia lesions in dogs; however, other CT signs were not associated with arthroscopic findings, and CT and arthroscopy can provide contradictory information. Osteophyte size is moderately correlated with cartilage erosion of the medial joint compartment.
Clinical Relevance— CT can provide valuable information for the investigation of dogs with elbow dysplasia, but the absence of CT signs (or the absence of arthroscopic abnormalities) does not rule out elbow lesions.     

Computed tomography in the diagnosis of malignant sinonasal tumours in three horses

Malignant tumours are uncommon in horses, but when they do occur, they are most frequently found in the head. Clinical findings, such as facial swelling and nasal discharge, are frequently encountered but are nonspecific. To highlight the usefulness of a computed tomography (CT) examination in malignancy in the equine head, this Case Report describes the CT features of a leiomyosarcoma, an osteosarcoma and a sarcoma in 3 horses. CT of the equine head was able to provide more information about the extent and severity of lesions than conventional radiography in these cases.     

Inefficacy of selegiline in treatment of canine pituitary-dependent hyperadrenocorticism

OBJECTIVE: To evaluate selegiline, a monoamine oxidase-B inhibitor, for treating dogs with pituitary-dependent hyperadrenocorticism. DESIGN: Prospective clinical trial using client-owned dogs with pituitary-dependent hyperadrenocorticism treated at The University Veterinary Centre, Sydney, from September 1999 to July 2001. PROCEDURE: Eleven dogs with pituitary-dependent hyperadrenocorticism treated with selegiline were monitored at days 10, 30 and 90 by clinical examination, tetracosactrin stimulation testing, urinary corticoid:creatinine ratio measurement and client questionnaire. Endogenous adrenocorticotropic hormone measurements were also performed on most dogs on days 0 and 90. No dog treated with selegiline had satisfactory control of disease. CONCLUSION: Selegiline administration was safe and free of side-effects at the doses used, but did not satisfactorily control disease in pituitary-dependent hyperadrenocorticism affected dogs.     

Computed tomography diagnosis of eight dogs with brain infarction

Objective Medical records of eight dogs presenting with acute onset of neurological signs and a diagnosis of brain infarction as determined by computed tomography (CT) imaging were reviewed. Design Retrospective single-centre case review Results Ischaemic infarction in the territory of the rostral cerebellar artery was identified in three spaniel-breed dogs. All cerebellar infarcts were non-haemorrhagic. Telencephalic infarcts were identified in five dogs, in the territories of the middle cerebral artery (2/5) and rostral cerebral artery (3/5). One of these dogs had an ischaemic infarction, but all other infarctions appeared haemorrhagic. All dogs were geriatric (≥8 years old), with concurrent medical conditions identified in six dogs. One dog was euthanased after diagnosis because of the severity of its neurological signs and one dog was euthanased as a result of associated renal disease 2 months after diagnosis. Six dogs were alive at least 1 year after diagnosis. Conclusions CT is useful in the diagnosis of cerebrovascular accident in dogs, which can present as a spectrum of images with early changes in attenuation and subtle mass effects detected after infarction. CT is particularly sensitive for detecting haemorrhagic infarction, but under-represent ischaemic and lacunar infarctions when compared with MRI.     

Computed tomography for the diagnosis of a lumbosacral nerve sheath tumour and management by hemipelvectomy

Computed tomography was used to define the gross extent of a lumbosacral plexus nerve sheath tumour in a 10-year-old crossbred dog. The tumour was also visualised ultrasonographically, which enabled a percutaneous biopsy to be taken. Hemipelvectomy was performed to achieve a clean margin of surgical excision.