Canine tonsillar polyps: characteristics, classification and review of the pathogenesis

Canine tonsillar polyps are uncommon. We describe 14 tonsillar polyps in dogs and review their classification and pathogenesis. All dogs were adult (3-13 years old). Females (10/14) were more affected than males (4/14). Most of the lesions were asymptomatic (10/14). All lesions were unilateral, pedunculated (9/14) or sessile (5/14), with a smooth (12/14) or papillary/verrucous surface (2/14). Histologically, polyps consisted of benign proliferation of lymphatic vessels, blood vessels, fibrous tissue and lymphoid tissue in variable proportions, with occasional adipose tissue (4/14). According to the main stromal components, polyps were categorized as lymphangiomatous (5/14), lymphangiolipomatous (2/14), lymphangiofibromatous (2/14), angiofibromatous (1/14), angiofibrolipomatous (1/14), lymphoid (2/14), and myxomatous (1/14). As the pathogenesis of these polyps remains unclear, we propose to replace the term inflammatory tonsillar polyp by a morphological diagnosis based on the stromal characteristics of the lesions. Simple surgical excision was curative in the 9 cases with available follow-up information

Novel Allelic Variants in the Canine Cyclooxgenase-2 (Cox-2) Promoter Are Associated with Renal Dysplasia in Dogs

Renal dysplasia (RD) in dogs is a complex disease with a highly variable phenotype and mode of inheritance that does not follow a simple Mendelian pattern. Cox-2 (Cyclooxgenase-2) deficient mice have renal abnormalities and a pathology that has striking similarities to RD in dogs suggesting to us that mutations in the Cox-2 gene could be the cause of RD in dogs. Our data supports this hypothesis. Sequencing of the canine Cox-2 gene was done from clinically affected and normal dogs. Although no changes were detected in the Cox-2 coding region, small insertions and deletions of GC boxes just upstream of the ATG translation start site were found. These sequences are putative SP1 transcription factor binding sites that may represent important cis-acting DNA regulatory elements that govern the expression of Cox-2. A pedigree study of a family of Lhasa apsos revealed an important statistical correlation of these mutant alleles with the disease. We examined an additional 22 clinical cases from various breeds. Regardless of the breed or severity of disease, all of these had one or two copies of the Cox-2 allelic variants. We suggest that the unusual inheritance pattern of RD is due to these alleles, either by changing the pattern of expression of Cox-2 or making Cox-2 levels susceptible to influences of other genes or environmental factors that play an unknown but important role in the development of RD in dogs

Immunohistochemical expression of MDR1-Pgp 170 in canine cutaneous and oral melanomas: pattern of expression and association with tumour location and phenotype

Canine melanoma (CMM) more commonly affects the oral mucosa and the cutis. CMM shares several features with human melanomas (HMM), included resistance to a broad variety of antineoplastic chemotherapy agents. P-glycoprotein 1 (Pgp) expression is a well-recognized feature of multi-drug resistance and the purpose of this study was to investigate its expression in treatment naïve CMM. We also investigated Pgp association with tumour location and histological features. Histology records of CMM were retrieved, including patients from 2012-2014. Twenty-five cases of CMM were included in this study. Results revealed that Pgp is expressed in CMM and oral tumours were more likely to have a membranous Pgp expression (100%) than cutaneous tumours (66.6%) (P = 0.010). Cytoplasmic and nuclear Pgp expression could also be identified. Results of this study bring useful data that help in understanding one of the possible mechanisms responsible of intrinsic chemotherapy resistance in canine CMM

Immunohistochemical expression of MDR1-Pgp 170 in canine cutaneous and oral melanomas: pattern of expression and association with tumour location and phenotype

Canine melanoma (CMM) more commonly affects the oral mucosa and the cutis. CMM shares several features with human melanomas (HMM), included resistance to a broad variety of antineoplastic chemotherapy agents. P-glycoprotein 1 (Pgp) expression is a well-recognized feature of multi-drug resistance and the purpose of this study was to investigate its expression in treatment naïve CMM. We also investigated Pgp association with tumour location and histological features. Histology records of CMM were retrieved, including patients from 2012-2014. Twenty-five cases of CMM were included in this study. Results revealed that Pgp is expressed in CMM and oral tumours were more likely to have a membranous Pgp expression (100%) than cutaneous tumours (66.6%) (P = 0.010). Cytoplasmic and nuclear Pgp expression could also be identified. Results of this study bring useful data that help in understanding one of the possible mechanisms responsible of intrinsic chemotherapy resistance in canine CMM

Histopathological and immunophenotypical characterization of a combined melanoma and mucoepidermoid carcinoma in a dog

El presente trabajo describe el primer caso de un carcinoma mucoepidermoide canino pobremente diferenciado en el que se ha observado una proliferación maligna de melanocitos. La masa tumoral se localizó a nivel del 7º cuerpo vertebral en perro de raza mestiza. No se detectaron otros signos macroscópicos de carcinoma y/o melanoma oral o epitelial. El examen microscópico reveló la proliferación conjunta de ambas subpoblaciones. La proliferación y colonización de melanocitos en tumores de origen no melánico es rara y no se conoce la causa. En Patología humana, se han descrito casos de carcinomas mucoepidermoides pigmentados, pero en todos los casos se consideró la proliferación melanocítica como hiperplasia, no observándose en ningún caso signos de neoplasia. No existen en Patología humana ni veterinaria ningún caso descrito de carcinoma mucoepidermoide concomitante con un melanoma maligno, siendo éste el primer caso descrito

Juvenile Nephropathy in a Boxer, a Rottweiler, a Collie and an Irish Wolfhound

Juvenile nephropathy was diagnosed in a Boxer, a Rottweiler, a Collie and an Irish Wolfhound dog, each presenting with signs compatible with chronic renal failure. The diagnosis in each case was based on the presence of persistence of poorly differentiated tissue (immature glomeruli and/or tubules, persistent mesenchyme) on histopathologic examination. Although juvenile nephropathy has been reported in many breeds of dog, this is the first report of the condition in the Collie and the Irish Wolfhound and only the second description in the Boxer and the Rottweiler. The possibility of an inherited origin of the condition in these four breeds is at present unknown