Canine Hyperadrenocorticism Due to Adrenocortical Neoplasia: Pretreatment Evaluation of 41 Dogs

This retrospective study identifies parameters that might separate dogs with hyperadrenocorticism caused by adrenocortical tumors from dogs with pituitary-dependent hyperadrenocorticism. Further, an attempt was made to identify factors that could separate dogs with adrenocortical adenomas from dogs with carcinomas. The records of 41 dogs with hyperadrenocorticism caused by adrenocortical neoplasia were reviewed. The history, physical examination, urinalysis, hemogram (CBC), chemistry profile adrenocorticotrophic hormone (ACTH) stimulation and low dose dexamethasone test results were typical of the nonspecific diagnosis of hyperadrenocorticism. The preceding information on the 41 dogs with adrenocortical tumors was compared with that from 44 previously diagnosed pituitary-dependent hyperadrenocorticoid dogs. There was no parameter which aided in separating these two groups of dogs. Thirty dogs with adrenocortical tumors were tested with a high-dose dexamethasone test and none had suppressed plasma cortisol concentrations 8 hours after IV administration of 0.1 mg/kg of dexamethasone. In 29 of the 41 adrenal tumor dogs, plasma endogenous ACTH was not detectable on at least one measurement (less than 20 pg/ml). The remaining 12 dogs from this group had nondiagnostic concentrations (20-45 pg/ml). Thirteen of 22 dogs (59%) with adrenocortical carcinomas had adrenal masses identified on abdominal radiographs and seven of 13 dogs (54%) with adrenocortical adenomas had radiographically visible adrenal masses. Thirteen of 17 adrenocortical carcinomas (76%) and five of eight adenomas (62%) were identified with ultrasonography. Radiographs of the thorax and ultrasonography of the abdomen identified most of the dogs (8 of 11) with metastatic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ki-67 and minichromosome maintenance-7 (MCM7) expression in canine pituitary corticotroph adenomas

Pituitary-dependent hyperadrenocorticism (PDH) caused by pituitary corticotroph adenoma is a common endocrine disorder in dogs. The ratio between pituitary height and the area of the brain (P/B) has been used to evaluate the pituitary size. A P/B ratio > 0.31 indicates an enlarged pituitary, whereas a P/B ratio ≤ 0.31 indicates a nonenlarged pituitary. The aim of this study was to investigate the expression of proliferation markers Ki-67 and minichromosome maintenance-7 (MCM7) in canine corticotroph adenomas in enlarged and in nonenlarged pituitaries and to evaluate their relation with the size of canine pituitary corticotroph adenomas. Ki-67 and MCM7 expression in ACTH-positive tumor cells was determined by dual-labeling immunohistochemistry in resected corticotroph adenomas from 15 dogs with PDH. The mean ± SD Ki-67 labeling index (LI) was 0.55% ± 0.59% in corticotroph adenomas with nonenlarged pituitaries and 1.6% ± 0.6% in adenomas with enlarged pituitaries. The MCM7 LI in corticotroph adenomas with nonenlarged pituitaries and in adenomas with enlarged pituitaries was 2.9% ± 2.2% and 10.9% ± 3.7%, respectively. The Ki-67 LI and MCM7 LI were significantly greater in the adenomas with enlarged pituitaries than in the adenomas with nonenlarged pituitaries (P < 0.01 and P < 0.01, respectively). The MCM7 LI was significantly greater than the Ki-67 LI in adenomas (P < 0.01). The Ki-67 LI was positively correlated with the MCM7 LI (r = 0.820, P < 0.01), and the P/B ratio was positively correlated with the Ki-67 LI (r = 0.560, P = 0.03) and the MCM7 LI (r = 0.854, P < 0.01). In conclusion, canine corticotroph adenomas in enlarged pituitaries show greater proliferation potential than do adenomas in nonenlarged pituitaries. MCM7 expression was significantly greater than Ki-67 expression in canine pituitary corticotroph adenomas. Thus, MCM7 may be superior to Ki-67 as a proliferation marker in pituitary tumors.     

Expression of the ACTH receptor, steroidogenic acute regulatory protein, and steroidogenic enzymes in canine cortisol-secreting adrenocortical tumors

Studies of human adrenocortical tumors (ATs) causing Cushing's syndrome suggest that hypersecretion of cortisol is caused by altered expression of steroidogenic enzymes and that steroidogenesis can only be maintained when there is expression of the ACTH receptor (ACTH-R). Here we report the screening for the mRNA expression of the ACTH-R, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase, 21-hydroxylase (all in 38 cortisol-secreting ATs), 17α-hydroxylase, and 11β-hydroxylase (both in 28 cortisol-secreting ATs). Real-time PCR (RT-PCR) was applied in all samples and was compared with that in normal canine adrenal glands. Messenger-RNA encoding StAR, steroidogenic enzymes, and ACTH-R were present in both normal adrenal glands and cortisol-secreting ATs. The amounts of mRNA encoding StAR and enzymes of the steroidogenic cluster needed for cortisol production did not differ significantly between either adenomas or carcinomas and normal adrenal glands. The amount of mRNA encoding ACTH-R was significantly lower in carcinomas than in normal adrenal glands (P = 0.008). In conclusion, RT-PCR analysis revealed no overexpression of StAR and steroidogenic enzymes in canine cortisol-secreting ATs. Significant downregulation of ACTH-R in carcinomas might be associated with the malignant character of the AT.     

Relationship between cell proliferation and tenascin-C expression in canine gastrointestinal tumours and normal mucosa

Tenascin-C is an extracellular matrix glycoprotein that has been implicated in cell proliferation and adhesion by in vitro experiments. Its expression is known to be increased in canine and human gastrointestinal tumours. The aim of this study was to investigate the possible relationship between cell proliferation and tenascin expression in these tumours. In tissue sections of normal stomach, small intestine and colon, and gastrointestinal epithelial tumours, the monoclonal antibody Ki-67, which is directed against a proliferation-associated nuclear antigen, was used to identify proliferating cells. Serial sections were also stained for tenascin. Serial sections stained for tenascin and Ki-67 were compared to determine whether there is a correlation between tenascin expression and tumour cell proliferation. In the normal gastric mucosa, Ki-67 positive cells were confined to the neck region and in the normal small intestinal mucosa positive cells were confined to the lower parts of the crypts. In adenomas and carcinomas, the frequency of positive cells was increased at the edges of adenomas and invasive tumour margins of carcinomas and there was inter- and intra-tumoural heterogeneity. Carcinomas with lymphatic invasion showed a high Ki-67-index. There was no relation between cell proliferation and tenascin expression in both normal tissues and tumours studied. The absence of a correlation between tenascin and Ki-67 expression suggests that the main function of tenascin in both normal tissues and tumours of the canine gastrointestinal tract is antiadhesion rather than proliferation.     

Expression of Ki-67, PCNA,and p27kip1 in canine pituitary corticotroph adenomas

Pituitary-dependent hypercortisolism (PDH), which is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, is a common endocrinopathy in dogs. Dogs with non-enlarged pituitaries harboring a microadenoma have a better prognosis than those with enlarged pituitaries. The aim of this study was to investigate the expression of the proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) and the cell-cycle inhibitor p27kip1 in corticotroph adenomas in enlarged and non-enlarged pituitaries. The expression of Ki-67, PCNA, and p27kip1 was analyzed by immunohistochemical staining of 17 pituitary adenoma samples harvested during pituitary surgery in dogs with PDH. The labeling index was calculated by counting the number of immunopositive cells per 1,000 cells. The mean (± standard deviation) labeling index for Ki-67 was 8.4% ± 14.2% for the group with enlarged pituitaries, and 8.8% ± 5.5% for the group with non-enlarged pituitaries; that for PCNA was 35.5% ± 12.2% and 37.0% ± 15.5%; and that for p27kip1 was 29.3% ± 22.6% and 42.5% ± 27.9%, respectively. No significant differences in Ki-67, PCNA, and p27kip1 labeling indices were found between enlarged and non-enlarged pituitaries. However, a trend toward significance was observed when comparing the expression of p27kip1 in enlarged pituitaries versus normal pituitary tissue. It is concluded that Ki-67 and PCNA are not useful as proliferative markers for studying the pathobiology of pituitary corticotroph adenomas in dogs.     

Comparison of mitotane treatment for adrenal tumor versus pituitary-dependent hyperadrenocorticism in dogs.

The purpose of this study was to determine the sensitivity of dogs with hyperadrenocorticism to treatment with the adrenocorticolytic agent mitotane. Specifically, we looked for differences in response to treatment using this drug in dogs with adrenocortical tumors (adrenal tumor hyperadrenocorticism, ATH) vs those with pituitary-dependent hyperadrenocorticism (PDH). For inclusion in this study, each dog must have had clinical signs, data base laboratory abnormalities, and endocrine screening test results consistent with the diagnosis of hyperadrenocorticism. Further, each dog had to have been treated for at least 6 months with mitotane and have histologic evidence for adrenocortical or pituitary neoplasia (all dogs were necropsied). Thirteen dogs with ATH (8 carcinomas, 5 adenomas) were identified. The ages and body weights of these 13 dogs were computer-matched to 13 dogs with PDH. All dogs were initially treated with approximately 50 mg of mitotane/kg/d of body weight. Reexaminations were performed after 7, 30, 90, and 180 days of treatment. Individual dosages varied widely after the initial 5 to 12 days of treatment. The mean (+/- SD) dose of mitotane (mg/kg/d) for the first 7 days of treatment was 47.5 +/- 9.4 for dogs with ATH vs 45.7 +/- 11.9 for dogs with PDH. The mean plasma cortisol concentrations 1 hour after ACTH administration at the 7-day recheck were significantly higher in dogs with ATH (502 +/- 386 nmol/L) than in dogs with PDH (88 +/- 94 nmol/L).(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of surgical treatment for hyperadrenocorticism caused by adrenocortical neoplasia in the dog: 25 cases (1980-1984)

Results of surgical treatment for neoplasia of the adrenal cortex that caused hyperadrenocorticism were evaluated in 25 dogs. Surgical examination of the adrenal glands was performed by use of a ventral midline approach in 24 dogs and a retroperitoneal approach in 1 dog. All 25 dogs had a unilateral, adrenocortical tumor. Histologic examination identified 14 adrenocortical carcinomas and 11 adenomas. Seven dogs with carcinoma had visible metastasis to the liver, 3 had local invasion into the caudal vena cava, and 1 had extension into the adjacent renal vein. Seven of the 9 dogs with metastasis were euthanatized at time of surgery. Of the remaining 18 dogs that survived surgery, 9 (4 with carcinoma and 5 with adenoma) developed serious postoperative complications including acute renal failure, pneumonia, and pulmonary artery thromboembolism; 8 of these dogs died or were euthanatized. Of the remaining 10 dogs, clinical signs associated with hyperadrenocorticism resolved in the 7 dogs that had adrenocortical adenoma and in 1 of the 3 dogs that had carcinoma. The remaining 2 dogs with carcinoma had persistent hyperadrenocorticism and were treated with high doses of mitotane. Although no response was observed in 1 dog with visible hepatic metastasis, a decrease in serum cortisol concentrations and resolution of clinical signs were detected in the other dog during prolonged daily administration of mitotane.     

Ultrasonographic characteristics of both adrenal glands in 15 dogs with functional adrenocortical tumors.

Ultrasonographic examination of both adrenal glands was performed in 15 dogs with functional adrenocortical tumors (FAT). Bilateral adrenal tumors were diagnosed in three of 15 dogs, and unilateral tumors were diagnosed in 12 of 15 dogs. Adrenal tumors were characterized by adrenal gland enlargement with loss of the normal shape and parenchymal structure. The contralateral adrenal gland could be imaged in all dogs with unilateral tumors. Based on size, shape, and parenchymal structure, the contralateral adrenal gland was similar to adrenal glands of normal dogs. The results of this study show that: 1) both adrenal glands should be imaged routinely in dogs with hyperadrenocorticism; 2) bilateral adrenocortical tumors seem to be more frequent than previously assumed; 3) one normal adrenal gland does not exclude the existence of a contralateral FAT; and 4) the functional atrophy of the contralateral adrenal gland in dogs with FAT may not be apparent ultrasonographically.     

Trabecular bone morphometry in beagles with hyperadrenocorticism and adrenal adenomas

Trabecular bone morphometry was done on rib samples of beagles with hyperadrenocorticism and adrenal adenomas to evaluate bone loss and the remodeling changes responsible. Beagles diagnosed as having clinical hyperadrenocorticism and those with milder or subclinical hyperadrenocorticism diagnosed on the basis of adrenal and pituitary lesions at necropsy had increased adrenal and pituitary gland weights. In a group of dogs with adrenal cortical adenomas there was atrophy of remaining cortex, and the combined weight of adrenal glands or pituitary weights were not increased. In dogs with clinical hyperadrenocorticism, mean trabecular bone volume was 25% less than controls (P = 0.10). In both clinical and subclinical hyperadrenocorticism groups, the extent of trabecular surface with unmineralized osteoid matrix and osteoblasts was significantly reduced. There were no changes in resorption surfaces or number of osteoclasts present. No bone changes were seen in dogs with adrenal adenomas. In dogs with hyperadrenocorticism it appeared that decreased bone formation was primarily responsible for the relative osteopenia that developed. Although parathyroid glands were moderately enlarged in those dogs for which weights were available, the bone changes were not those of increased remodeling expected in hyperparathyroidism.     

Cytochrome b5 expression in gonadectomy-induced adrenocortical neoplasms of the domestic ferret (Mustela putorius furo)

Whereas the adrenal glands of healthy ferrets produce only limited amounts of androgenic steroids, adrenocortical neoplasms that arise in neutered ferrets typically secrete androgens or their derivative, estrogen. The 17,20-lyase activity of cytochrome P450 17alpha-hydroxylase/17,20-lyase (P450c17) must increase to permit androgen biosynthesis in neoplastic adrenal tissue. We screened ferret adrenocortical tumor specimens for expression of cytochrome b(5) (cyt b(5)), an allosteric regulator that selectively enhances the 17,20-lyase activity of P450c17. Cyt b(5) immunoreactivity was evident in 24 of 25 (96%) adrenocortical adenomas/carcinomas from ferrets with signs of ectopic sex steroid production. Normal adrenocortical cells lacked cyt b(5), which may account for the low production of adrenal androgens in healthy ferrets. Other markers characteristic of gonadal somatic cells, such as luteinizing hormone receptor, aromatase, and GATA4, were coexpressed with cyt b(5) in some of the tumors. We concluded that cyt b(5) is upregulated during gonadectomy-induced adrenocortical neoplasia and is a marker of androgen synthetic potential in these tumors.     

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.     

Ki-67 and Vascular Endothelial Growth Factor Expression in Intracranial Meningiomas in Dogs

Background: Tumor proliferation in human intracranial meningiomas can be defined by the reactivity of the monoclonal antibody MIB-1 to the Ki-67 antigen. Vascular endothelial growth factor (VEGF), a pro-angiogenic factor, is a predictive marker for survival of dogs with intracranial meningiomas.
Hypothesis: Ki-67 is expressed in canine intracranial meningiomas and is associated with VEGF expression. Ki-67 expression is a prognostic marker for patient outcome.
Animals: Seventy client-owned dogs with WHO grade I intracranial meningiomas.
Methods: Retrospective study assessing the degree of immunostaining for Ki-67 by MIB-1 and VEGF expression in intracranial meningioma tissue from dogs. MIB-1 Labeling Index (LI) was calculated with Image J NIH-software. Extent, intensity, and distribution of VEGF-expression was assessed semiquantitatively. Cross tabulations with Fisher's exact tests and nonparametric Spearman's rank correlations were performed to identify associations between VEGF expression and MIB-1 LI. Fifteen dogs underwent postsurgical radiotherapy and were included in survival analysis. The effect of MIB-1 LI on survival was examined by Kaplan-Meier and Cox proportional hazards regression procedures.
Results: Ki-67 staining was positive in 91% (64/70) and VEGF expression was detected in 96% (67/70). There was no significant association between VEGF expression and MIB-1 LI. MIB-1 LI was not associated with survival.
Conclusions and Clinical Importance: MIB-1 antibody can be used to document cell proliferation in intracranial meningiomas in dogs, but does not predict outcome. No association between VEGF as a marker of angiogenesis and tumor proliferation was found. Angiogenesis might be a more important predictor of meningioma activity in dogs than is Ki-67.     

The Utrecht Score: A novel histopathological scoring system to assess the prognosis of dogs with cortisol‐secreting adrenocortical tumours

A cortisol‐secreting adrenocortical tumour (ACT) is the cause of naturally occurring canine hypercortisolism in approximately 15% to 20% of cases. The differentiation between an adrenocortical adenoma and carcinoma is usually based on histopathology. However, histopathological parameters have never been linked to the dogs' survival. Moreover, in human medicine the inter‐observer variability of some histopathological parameters that are used for ACTs is high. The objective of this study was to establish a reliable and easy‐to‐use histopathological scoring system for cortisol‐secreting ACTs that can assess the prognosis of dogs after adrenalectomy. Cortisol‐secreting ACTs of 50 dogs, collected between 2002 and 2015, were included in this study. Twenty histopathological features were assessed by one veterinary pathologist and one resident in veterinary pathology. In addition, the Ki67 proliferation index was assessed by two observers. Only parameters with intra‐ and inter‐observer agreement scores (intra‐class correlation or Cohen's kappa coefficient) of ≥0.40 were included in survival analyses. Use of multivariate forward stepwise regression analysis with associated hazard ratios led us to a scoring system which we call the Utrecht score: the Ki67 proliferation index, +4 if more than 33% of the tumour cells have clear/vacuolated cytoplasm and + 3 if necrosis is present. Using cut‐off values of 6 and 11, we could distinguish three groups that had significantly shorter survival times with increasing Utrecht scores. We conclude that the Utrecht score can be used to assess the prognosis of dogs with cortisol‐secreting ACTs after adrenalectomy, which can help to select high‐risk dogs that might benefit from adjuvant treatment or additional monitoring.     

Argyrophilic nucleolar organizing regions and Ki67 equally reflect proliferation in fine needle aspirates of normal, hyperplastic, inflamed, and neoplastic canine lymph nodes (n = 101)

BACKGROUND: The count of argyrophilic nucleolar organizing regions (AgNOR) has been considered a useful variable that reflects cellular proliferation in canine lymph nodes, but it has not been compared with other markers of proliferation. Hypothesis: Ki67 and AgNORs are equally useful as markers of tissue proliferation in fine needle aspirates of canine lymph nodes. ANIMALS: A total of 101 dogs. MATERIAL AND METHODS: Prospective, observational study of a convenience sample of dogs. Two smears were prepared for a May-Gruenwald-Giemsa stain and a Ki67/AgNOR double stain. In addition, CD3/CD79a immunostaining was performed when cytologic examination revealed a lymphoma. The dogs were grouped as normal (n = 26), reactive hyperplasia (n = 25), lymphadenitis (n = 31), and lymphoma (n = 19), based on the physical examination and the cytologic findings. The AgNOR count/cell, AgNOR area/cell and the percentage of cells staining positive for Ki67 were evaluated in 100-167 cells (median, 113 cells) by using automatic image analysis. RESULTS: Mean (SD) AgNOR counts/cell were 1.36 +/- 0.19 in normal dogs, 1.55 +/- 0.26 in lymphadenitis, 1.65 +/- 0.32 in reactive hyperplasia, and 3.67 +/- 1.08 in lymphoma. The percentage of Ki67 positive cells was 2.67 +/- 0.99% in normal lymph nodes, 5.04 +/- 3.34% in lymphadenitis, 5.36 +/- 2.14% in reactive hyperplasia, and 30.2 +/- 10.8% in lymphoma. All variables were significantly higher in dogs with lymphoma compared with the other groups (P < .0001). The sensitivity and the specificity of the AgNOR count for diagnosing lymphoma were 95 and 96% at a cutoff value of >2.04 AgNORs/cell. The cutoff value for the Ki67 positive cells was >10.40% (sensitivity, 95%; specificity, 98%). CONCLUSION AND CLINICAL IMPORTANCE: The results indicated that both AgNOR and Ki67 counts were good diagnostic tools for assessment of proliferation in aspirates of canine lymph nodes.     

Cell proliferation of epidermis, hair follicles, and sebaceous glands of beagles and cocker spaniels with healthy skin

Cell proliferation kinetic values were established for the epidermis, hair follicle epithelium, and sebaceous glands of 10 Beagles and 4 Cocker Spaniels with healthy skin and coats. Values were established by intradermal pulse-labeling injections of [3H]thymidine, examination of cutaneous biopsied tissues, and autoradiography. The epidermal basal cell-labeling index was 1.41 +/- 0.46% for Beagles and 1.71 +/- 0.56% for Cocker Spaniels. The hair follicle basal cell-labeling index was 1.46 +/- 0.78 and 1.07 +/- 0.42%, respectively. Calculated epidermal cell-renewal time for viable layers of the epidermis was 23.38 +/- 5.93 days for Beagles and 20.97 +/- 4.92 days for Cocker Spaniels. Differences between cell kinetic data for the 2 breeds were not significant (P greater than 0.05). The basal cell-labeling index for the sebaceous gland was significantly (P = 0.009) lower for Cocker Spaniels (0.40 +/- 0.18%) than for Beagles (1.81 +/- 1.08%). Seemingly, epidermal and follicular cell proliferation kinetics in healthy dogs was similar between the 2 breeds, whereas sebaceous gland basal cells were less proliferative in healthy Cocker Spaniels than in healthy Beagles.     

Ultrasonographic Characteristics of the Adrenal Glands in Dogs With Pituitary-Dependent Hyperadrenocorticism: Comparison With Normal Dogs

Ultrasonographic evaluation of the adrenal glands was performed in 10 dogs with pituitary-dependent hyperadrenocorticism (PDH) and in 10 age- and weight-matched healthy control dogs. Thickness, shape, and echogenicity were determined for each adrenal gland. Adrenal thickness in dogs with PDH (median, 10 mm-left; 8.5 mm-right) was significantly greater than thickness in control dogs (median, 6 mm-left; 6 mm-right). Other ultrasonographic characteristics associated with PDH included bilaterally symmetrical adrenomegaly and maintenance of normal adrenal shape. Adrenal echogenicity was homogeneous and less than that of the adjacent renal cortex in 8 of 10 dogs with PDH and in 10 of 10 control dogs. Heterogenous echogenicity was present in 2 of 10 dogs with PDH, and was associated with nodular cortical hyperplasia in one of those dogs. Results of this study confirm the difference in sonographic appearance between PDH-induced bilateral cortical hyperplasia and functional adrenocortical neoplasia, and show a difference in so-nographically determined adrenal size between healthy dogs and dogs with PDH. J Vet Intern Med 1996; 10:110–115. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Detection of the Ki-67 Proliferation Associated Nuclear Epitope in Normal Canine Tissues Using the Monoclonal Antibody MIB-1

This report describes the immunohistochemical detection of the Ki-67 proliferation associated nuclear epitope by means of the MIB-1 monoclonal antibody (mAb) in paraffin tissue sections from nine samples of 16 tissues obtained from nine dogs. Three parameters were considered: the localization of the cells expressing the Ki-67 epitope, the cytological characteristics of the Ki-67 expression, and the proliferative activity of some of the tissues measured by means of the proliferative index (percentage of Ki-67 positive cells measured on 500 and 1000 cells). The MIB-1 mAb reacts with the nuclei of proliferating cells, as in humans. The proliferative index was far from representative, but we were able to give a range of values concerning the proliferative activity of normal tissues. This study serves as a basis for the expression of the Ki-67 antigen by normal canine tissues in order to visualize the proliferative compartments and, thus, allows its application as a proliferative marker in routine veterinarian histopathology.     

Surgical treatment of adrenocortical tumors: 21 cases (1990-1996)

Twenty-four adrenocortical tumors were surgically removed from 21 dogs. Histopathological examination confirmed 18 carcinomas and six adenomas. Four dogs died in the perioperative period. Fifteen of the 17 dogs that survived the perioperative period had long-term resolution of their clinical signs. Two dogs with incompletely resected tumors were treated with mitotane to control their clinical signs. Overall median Kaplan-Meier life-table survival for dogs with carcinomas was 778 days (range, one to 1,593 days). Median survival for dogs with adenomas was not reached (range, 11 to 730 days). Histopathological diagnosis, histopathological cellular features, age of the dog, and tumor size were not prognostic of outcome.     

Apoptotic and proliferation indexes in canine lymphoma.

Proliferative and apoptotic fractions of tumors were evaluated in 41 dogs with lymphoma for prediction of response to chemotherapy. All dogs had advanced clinical stage tumors, were untreated prior to study, and received identical induction-remission chemotherapy. Tumor cell proliferation was determined in all pretreatment biopsy specimens and in 18 specimens collected at the time of clinical relapse from remission. Quantitative measures included mitotic index and immunoreactivities for proliferating cell nuclear antigen (PCNA) and Ki-67. Apoptotic index was evaluated from 40 dogs pretreatment and from 16 dogs at the time of first relapse. Pretreatment tumor values for Ki-67, PCNA, and apoptosis were compared with posttreatment values. The median first relapse-free interval (RFI) and overall survival (OS) time were 174 days and 445 days, respectively. Of the proliferation markers, only the results of the Ki-67 analysis were predictive for duration of the first RFI but not OS. Pretreatment apoptotic index was also predictive of the duration of first RFI but not OS. No significant predictive value for comparison of the pretreatment and postrelapse values was demonstrated. Ki-67 labeling index and apoptotic indexes were combined to form both a proliferation/apoptotic ratio (PAR) and a sum, or turnover index. Only the PAR was predictive for duration of first RFI on multivariate analysis. Other variables that were evaluated for their influence on treatment outcome included patient age, weight, gender, clinical stage, clinical substage, and tumor immunophenotype. Of these variables, only immunophenotype was found to be of value for predicting duration of first RFI and OS.     

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.