Estrogen Receptor and Signal Transducer and Activator of Transcription 3 Expression in Equine Mammary Tumors.

Equine mammary tumors are uncommon, and relatively sparse histopathologic and molecular data exist. The present study describes the histopathologic features of 7 such tumors, which exhibited infiltrative growth, intermediate to high mitotic rates, and focally extensive necrosis. The tumors exhibited variably strong staining for vimentin and cytokeratin 14, as well as frequently weak cytoplasmic staining for pan-cytokeratin. E-cadherin expression was strong. Interestingly, a subgroup of the tumors exhibited strong nuclear staining for estrogen receptor α. Three of 7 tumors exhibited nuclear expression of the transcription factor STAT3, suggesting that STAT3 was transcriptionally active. Rare to absent nuclear STAT3 expression was observed in carcinomas exhibiting moderate to intense staining for cytokeratin 14. This investigation confirms previous investigators' assertions that equine mammary tumors have a malignant phenotype. A subset of the equine mammary tumors exhibited estrogen receptor α expression, suggesting that these tumors may potentially have similar molecular characteristics to their feline and canine counterparts.

Proposal of a 2-tier histologic grading system for canine cutaneous mast cell tumors to more accurately predict biological behavior.

Currently, prognostic and therapeutic determinations for canine cutaneous mast cell tumors (MCTs) are primarily based on histologic grade. However, the use of different grading systems by veterinary pathologists and institutional modifications make the prognostic value of histologic grading highly questionable. To evaluate the consistency of microscopic grading among veterinary pathologists and the prognostic significance of the Patnaik grading system, 95 cutaneous MCTs from 95 dogs were graded in a blinded study by 28 veterinary pathologists from 16 institutions. Concordance among veterinary pathologists was 75% for the diagnosis of grade 3 MCTs and less than 64% for the diagnosis of grade 1 and 2 MCTs. To improve concordance among pathologists and to provide better prognostic significance, a 2-tier histologic grading system was devised. The diagnosis of high-grade MCTs is based on the presence of any one of the following criteria: at least 7 mitotic figures in 10 high-power fields (hpf); at least 3 multinucleated (3 or more nuclei) cells in 10 hpf; at least 3 bizarre nuclei in 10 hpf; karyomegaly (ie, nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold). Fields with the highest mitotic activity or with the highest degree of anisokaryosis were selected to assess the different parameters. According to the novel grading system, high-grade MCTs were significantly associated with shorter time to metastasis or new tumor development, and with shorter survival time. The median survival time was less than 4 months for high-grade MCTs but more than 2 years for low-grade MCTs.

Recommended guidelines for submission, trimming, margin evaluation, and reporting of tumor biopsy specimens in veterinary surgical pathology.

Neoplastic diseases are typically diagnosed by biopsy and histopathological evaluation. The pathology report is key in determining prognosis, therapeutic decisions, and overall case management and therefore requires diagnostic accuracy, completeness, and clarity. Successful management relies on collaboration between clinical veterinarians, oncologists, and pathologists. To date there has been no standardized approach or guideline for the submission, trimming, margin evaluation, or reporting of neoplastic biopsy specimens in veterinary medicine. To address this issue, a committee consisting of veterinary pathologists and oncologists was established under the auspices of the American College of Veterinary Pathologists Oncology Committee. These consensus guidelines were subsequently reviewed and endorsed by a large international group of veterinary pathologists. These recommended guidelines are not mandated but rather exist to help clinicians and veterinary pathologists optimally handle neoplastic biopsy samples. Many of these guidelines represent the collective experience of the committee members and consensus group when assessing neoplastic lesions from veterinary patients but have not met the rigors of definitive scientific study and investigation. These questions of technique, analysis, and evaluation should be put through formal scrutiny in rigorous clinical studies in the near future so that more definitive guidelines can be derived.

Salmonella enterica serovar typhimurium trxA mutants are protective against virulent challenge and induce less inflammation than the live-attenuated vaccine strain SL3261.

In Salmonella enterica serovar Typhimurium, trxA encodes thioredoxin 1, a small, soluble protein with disulfide reductase activity, which catalyzes thiol disulfide redox reactions in a variety of substrate proteins. Thioredoxins are involved as antioxidants in defense against oxidative stresses, such as exposure to hydrogen peroxide and hydroxyl radicals. We have made a defined, complete deletion of trxA in the mouse-virulent S. Typhimurium strain SL1344 (SL1344 trxA), replacing the gene with a kanamycin resistance gene cassette. SL1344 trxA was attenuated for virulence in BALB/c mice by the oral and intravenous routes and when used in immunization experiments provided protection against challenge with the virulent parent strain. SL1344 trxA induced less inflammation in murine spleens and livers than SL3261, the aroA mutant, live attenuated vaccine strain. The reduced splenomegaly observed following infection with SL1344 trxA was partially attributed to a reduction in the number of both CD4(+) and CD8(+) T cells and B lymphocytes in the spleen and reduced infiltration by CD11b(+) cells into the spleen compared with spleens from mice infected with SL3261. This less severe pathological response indicates that a trxA mutation might be used to reduce reactogenicity of live attenuated vaccine strains. We tested this by deleting trxA in SL3261. SL3261 trxA was also less inflammatory than SL3261 but was slightly less effective as a vaccine strain than either the SL3261 parent strain or SL1344 trxA.

Ascites is a negative prognostic indicator in chronic hepatitis in dogs.

BACKGROUND: Chronic hepatitis (CH) in dogs is common but little is known about factors associated with survival. Ascites is a well-recognized negative prognostic indicator in humans. HYPOTHESIS: Ascites is a negative prognostic indicator in CH in dogs. ANIMALS: Thirty-four dogs with histologically confirmed CH presented to 1 institution between 1996 and 2005. METHODS: Retrospective observational study. CH was diagnosed by histopathology of liver tissue according to the WSAVA criteria. Ascites was diagnosed by abdominal ultrasound. The association of ascites with survival from diagnosis or onset of owner-reported clinical signs until death from any cause or from liver disease was analyzed. Ascitic and nonascitic groups were further analyzed for differences in treatment and sex. RESULTS: Fourteen of 34 dogs had ascites. Survival from diagnosis to death from liver disease was 0.4 months (95% confidence interval [CI], 0.2-0.6) for ascitic dogs and 24.3 months (CI 11.4-37.1) for nonascitic dogs (P < .001), and from onset of signs to death from liver disease was 2.0 months (CI 0.0-5.6) for ascitic dogs and 33.0 months (CI 8.6-57.4) for nonascitic dogs (P= .0020). Diet and spironolactone use differed between groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Ascites is a significant negative prognostic indicator in dogs with CH. Veterinarians and owners can use this information to aid clinical decision making in affected dogs.

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.

Leiomyosarcoma of the pericardium, with epicardial metastases and peripheral eosinophilia in a dog.

A dog with a history of dyspnoea, anorexia and ascites showed on examination signs of right-sided heart failure, pleural effusion and peripheral eosinophilia. Diagnostic imaging suggested the presence of a mediastinal mass, and histopathological and immunohistochemical examination of a biopsy sample led to a diagnosis of leiomyosarcoma. On post-mortem examination, an extensive mass was found, which encircled the heart and obliterated the pericardial sac, with probable metastatic spread to the epicardium. Eosinophilic infiltration of the neoplastic mass, lamina propria of the stomach and duodenum, interstitium of the kidney, and submucosa of the bladder was consistent with a possible paraneoplastic eosinophilia.

Congenital hyposomatotropism in a domestic shorthair cat presenting with congenital corneal oedema.

A six-month-old, female, domestic shorthair cat was presented with a history of failure to grow and bilateral corneal opacity caused by corneal oedema. Congenital hyposomatotropism and possible secondary hypothyroidism were diagnosed on the basis of fasting serum levels of insulin-like growth factor-1 and thyroxine levels, respectively. These endocrinopathies are rare in the cat and have not been reported to cause ocular signs. The cat died during investigation of these diseases, and histopathological examination of the eyes showed significantly reduced corneal endothelial cell density and number of corneal epithelial cell layers when compared with age-matched healthy control corneas. These changes were implicated in the development of the corneal oedema.

Advances in the diagnosis and management of cutaneous mast cell tumours in dogs.

Mast cell tumours are one of the most common tumours of the canine skin and have a reputation for being difficult to manage because of their variable clinical presentation, behaviour and response to treatment. This review of recent literature on canine mast cell tumours suggests that the majority of such tumours may not be as bad as their reputation suggests. Most grade I and grade II tumours can be managed successfully by good surgery. Recent literature also calls into question the utility of clinical staging systems and the value of assessing surgical margins for prognosis and highlights the paucity of well-conducted, case-controlled clinical trials in assessing the efficacy of medical management of high-risk tumours. In terms of more basic research, recent studies have implicated the stem cell factor receptor KIT as having a role in the aetiology of canine mast cell tumours and there appears to be an association between c-kit mutation and higher grade of tumour. This may offer a possible target for new therapeutic approaches.

Survival of 54 cats with oral squamous cell carcinoma in United Kingdom general practice.

OBJECTIVES: To determine the survival of 54 cats with histologically confirmed feline oral squamous cell carcinoma (FOSCC) treated in UK general practice and to determine factors predictive for survival. METHODS: Cases were identified from consecutive samples submitted for histological diagnosis. Observational and survival data were collated retrospectively from submitting practices. Immunohistochemical analysis of cyclooxygenase (COX) expression variables was available using previously published data. Kaplan-Meier product limit estimation for overall survival and Cox proportional hazards regression for potential explanatory variables were performed. RESULTS: The overall median survival time was 44 days [95 per cent confidence interval (CI): 31-79] and 1 year survival was 9.5 per cent. Variables associated with survival were whether the cat was pedigree [hazard ratio (HR)=8.17, 95 per cent CI: 1.96-34.12], whether the cat received non-steroidal anti-inflammatory drug (NSAID) therapy after diagnosis (HR=0.46, 95 per cent CI: 0.21-0.98) and whether the COX-1 staining distribution was patchy rather than diffuse (HR=0.25, 95 per cent CI: 0.08-0.014). CLINICAL SIGNIFICANCE: This study suggests that although the prognosis for inoperable FOSCC remains poor, palliative treatments may offer a survival advantage that compares favourably with more aggressive treatment methods. Further work is needed to evaluate NSAID therapy in this disease, in particular to determine whether the potential survival advantage is because of an analgesic or anticancer effect or both. COX-1 distribution patterns may have a role as a prognostic indicator in this disease.

Viability of Sarcocystis neurona sporocysts and dose titration in gamma-interferon knockout mice.

Gamma-interferon knockout mice have become the model animal used for studies on Sarcocystis neurona. In order to determine the viability of S. neurona sporocysts and to evaluate the course of the disease in these mice, sporocysts were collected from opossums (Didelphis virginiana), processed, and stored for varying periods of time. Gamma-interferon knockout mice were then inoculated orally with different isolates at different doses. These animals were observed daily for clinical signs until they died or it appeared necessary to humanely euthanize them. 15 of 17 (88%) mice died or showed clinical signs consistent with neurologic disease. The clinical neurologic symptoms observed in these mice appeared to be similar to those observed in horses. 15 of 17 (88%) mice were euthanized or dead by day 35 and organisms were observed in the brains of 13 of 17 (77%) mice. Dose appeared not to effect clinical signs, but did effect the amount of time in which the course of disease was completed with some isolates. The minimum effective dose in this study was 500 orally inoculated sporocysts. Efforts to titrate to smaller doses were not attempted. Direct correlation can be made between molecularly characterized S. neurona sporocysts and their ability to cause neurologic disease in gamma-interferon knockout mice.

Colonic vascular ectasia (angiodysplasia) in a juvenile dog.

An eight-month-old female English springer spaniel was presented with weight loss and severe haematochezia. Upper and lower endoscopy identified small intestinal inflammatory bowel disease and a vascular malformation within the descending colon. The colonic lesion was excised at coeliotomy and identified histopathologically as a colonic vascular ectasia. All clinical signs resolved following surgery and continued dietary management. To the authors' knowledge this is only the second published report of CVE in a juvenile dog and the first to survive to long term follow up.

Vascular endothelial growth factor (VEGF) and VEGF receptor expression in biopsy samples of liver from dogs with congenital portosystemic shunts.

Surgical attenuation of a congenital portosystemic shunt (CPSS) results in increased liver mass, development of intrahepatic portal vasculature and improved liver function. Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. The aim of this study was to investigate the role of VEGF and its receptor in the hepatic response to CPSS surgery. The study included 99 dogs with CPSS treated with either partial or complete suture attenuation. Forty-four dogs with partial attenuation underwent a second surgery for complete attenuation. The expression of VEGF and VEGF receptor 2 (VEGFR2) in biopsy samples of liver was assessed by immunohistochemistry with rabbit anti-human VEGF polyclonal antibody and mouse anti-human VEGFR2 monoclonal antibody. Expression of these molecules was graded. The proportion of samples expressing VEGF was significantly greater in samples from dogs with CPSS compared with control samples (P=0.04) and the proportion of samples expressing VEGFR2 was significantly greater in control samples compared with samples from dogs with CPSS (P=0.04). VEGF labelling grade decreased significantly (P=0.038) and VEGFR2 increased significantly (P=0.046) between first and second surgery. The decrease in VEGF may reflect transient expression, preferential expression of other factors, reperfusion of existing vessels and/or increased angiogenesis before surgery in the form of arterialization and subsequent reduction due to improved portal blood flow. Partial suture attenuation was associated with a degree of 'normalization' of VEGF and VEGFR2 expression when compared with the control samples. Further investigation is needed to provide more information on the hepatic response to CPSS surgery.

Multiple small intestinal pseudodiverticula associated with lymphoma in three horses.

Three mature horses presented with progressive weight loss, inappetence, ventral abdominal oedema and lethargy. Two of the animals had intermittent signs of low grade abdominal pain. At presentation, all 3 had hypoalbuminaemia; 2 had hyperfibrinogenaemia and the other had neutrophilia. An oral glucose tolerance test was performed in 2 cases, both of which demonstrated impaired glucose absorption. One pony treated with corticosteroids failed to improve and developed peritonitis and was subjected to euthanasia after 2 weeks. One pony had small intestinal biopsies obtained via a standing flank laparotomy, which revealed a mainly mononuclear cell infiltrate of the mucosa. It failed to respond to treatment with antibiotics and corticosteroids and, after 2 months, developed sternal oedema in addition to the ventral abdominal oedema and peritonitis and was subjected to euthanasia. The remaining pony deteriorated despite symptomatic therapy and was subjected to euthanasia after one week. At post mortem examination, all 3 animals had multifocal lesions of small intestinal wall thickening, mucosal ulceration, pseudodiverticula and enlarged mesenteric lymph nodes. One pony also had a multinodular mass at the root of the mesentery, a mediastinal mass and a lung mass. Histological examination confirmed the presence of lymphoma of the intestinal wall at post mortem examination in each case and immunohistochemistry (including retrospective evaluation of the intestinal biopsies obtained from the pony that underwent a flank laparotomy) indicated that the lymphomas were of T cell origin.

Chronic hepatitis in the English springer spaniel: clinical presentation, histological description and outcome.

Medical records and liver histology of 68 English springer spaniels (ESS) with a histological diagnosis of CH were reviewed retrospectively. PCR was performed on liver tissue for canine adenovirus-1 (CAV-1), canine parvovirus, canine herpesvirus and pathogenic Leptospira species. Follow-up information was obtained to calculate survival times. Median age at presentation was three years seven months (range, seven months to eight years five months) and there were 48 female and 20 male dogs. Clinical signs were non-specific and five dogs were asymptomatic. All dogs had an increase in serum activity of one or more hepatobiliary enzymes. Histopathology demonstrated hepatocyte necrosis and apoptosis with varying amounts of fibrosis. A predominantly lymphoplasmacytic infiltrate throughout the hepatic parenchyma was found in all 68 dogs, but 45 of these dogs also had a neutrophilic component to the inflammatory infiltrate. There was no significant copper accumulation and no aetiological agent was identified by PCR. The median survival time was 189 days (range, 1 to 1211 days), 38 dogs died within three months and 12 dogs survived more than a year following diagnosis.

Observational study of 14 cases of chronic pancreatitis in dogs.

This study reports the clinical, clinicopathological and ultrasonographic findings from dogs with chronic pancreatitis (CP). Fourteen dogs with clinical signs consistent with CP and histological confirmation of the disease were evaluated. Abdominal ultrasound and clinical pathology results were recorded. Sensitivities of pancreatic enzymes for diagnosis of CP were calculated with two different cut-off values. The mean age of affected dogs was 9.1 years. Spaniels were the most common breed with CP, representing seven of the 14 dogs in this study. CP was histologically severe in nine cases. Most dogs showed chronic low-grade gastrointestinal signs and abdominal pain. Five dogs had exocrine pancreatic insufficiency and five dogs had diabetes mellitus. The sensitivity of elevated trypsin-like immunoreactivity for CP was 17 per cent. The sensitivities of canine pancreatic lipase immunoreactivity, lipase and amylase for CP were 44 to 67 per cent or 14 to 28 per cent depending on the cut-off value used. Cholesterol was elevated in 58 per cent of samples. Liver enzymes were often elevated. The pancreas appeared abnormal on 56 per cent of ultrasound examinations. Ten dogs had died by the end of the study period; only one case was due to CP.

Prevalence of hepatic lesions at post-mortem examination in dogs and association with pancreatitis.

OBJECTIVES: To assess the prevalence of canine chronic hepatitis (CH) and other liver diseases in first opinion practice and identify associations with concurrent chronic pancreatitis (CP). METHODS: One large section of left lateral lobe of liver was taken from 200 unselected canine post-mortem examinations from first opinion practices. Histological changes were categorised based on WSAVA criteria. Prevalence of CH and other liver diseases were calculated. Relative risks (RR) for liver histopathology in association with CP and for CH in different breeds were also calculated. RESULTS: The prevalence of CH was 12%. Some breeds had an increased RR of CH, although sample sizes were small. Dogs with CP had an increased RR of reactive hepatitis but no significant association with the other liver diseases. CLINICAL SIGNIFICANCE: CH is common in the first opinion dog population but less common than CP. CP was significantly associated with reactive hepatitis but not CH. Possible breed associations mirrored another recent UK study. Some dogs with CP may be erroneously diagnosed clinically as having CH on the basis of increased serum liver enzymes because of concurrent reactive hepatitis if the diagnosis is not confirmed histologically.