Knowledge of the geographical distribution of feline immunodeficiency virus (FIV) subtypes is important for understanding different disease courses and for vaccine design. Intersubtype recombination may develop in areas where more than one subtype is prevalent and has the potential to create new transmittable variants with novel pathogenic properties. In this study, 40 FIV-positive DNA samples were classified by sequence analysis of the LTR–gag region. Phylogenetic analysis indicated that 32 Canadian FIV isolates clustered with previously identified subtypes A, B and C and that subtype A was most frequent in Ontario. Four strains with inconsistent clade assignment were further analysed by sequencing of the env–LTR regions. Comparisons of phylogenetic trees constructed from the two different regions of the genome and analysis of similarities to reference sequences yielded classification of three samples as A/B and one as A/C intersubtype recombinants. Although the A/B recombinant samples were obtained from unrelated cats in geographically disparate regions, a common breakpoint was consistently identified within gag. In addition, there was no evidence of co-infection with parental strains of subtypes A and B as indicated by PCR-based limiting dilution assays, although these assays allowed for the identification of two different recombinant viruses co-existing in one sample. Both sequences contained the same breakpoint. These findings suggested that a new circulating recombinant FIV may be enzootic in Ontario.

Abstract. This report describes the gross, microscopic, and immunohistochemical features of an invasive epithelial mesothelioma in an 11-year-old neutered male Golden Retriever. The tumor involved the pericardium, pleura, mediastinum, and peritoneum and invaded into submesothelial tissues. Neoplastic cells in the thoracic fluid showed prominent features of malignancy in a background of mixed inflammatory cells and scattered erythrocytes. Histologically, the tumor consisted of nests of epithelioid cells with frequent mitotic figures and multinucleation that infiltrated submesothelial tissues. Neoplastic cells strongly coexpressed vimentin and cytokeratin intermediate filaments, which assisted in the differentiation from other epithelial tumors of nonmesothelial origin.

No abstract

Flow cytometry is a highly sensitive and specific method for simultaneous analysis of multiple parameters of individual cells in a suspension. It has a range of applications in veterinary medicine, and it is increasingly used in veterinary oncology as more species-specific antibodies are generated and cross-reactivity of antibodies is characterized. Two major applications in veterinary oncology are (1) immunophenotyping with a panel of fluorescently labeled antibodies to assess expression of cell markers and (2) determination of the DNA content of cells with fluorescent dyes that bind nucleic acids. The diagnostic and prognostic value of classifying round cell tumors of animals-especially, lymphocyte proliferations-remains to be fully determined, but studies to date have indicated benefit to patient management. Similarly, determining the proliferating fraction of tumors through DNA analysis remains to be standardized and validated in veterinary oncology but shows promise as an adjunct to morphologic tumor classification. This article reviews technical aspects of flow cytometry, availability of antibodies suitable for studies in domestic animals, and applications in veterinary oncology with emphasis on characterization of round cell tumors.

Although thoracoscopy is associated with less postoperative pain, shorter hospitalization times, and faster patient recovery than sternotomy procedures, complications are also possible with minimally invasive endoscopic surgery. Portal site metastasis can develop from contamination of portal sites with cells on instruments or cannulas or via leakage of effusion fluid. Although rare, this potential complication should be discussed with owners prior to performing the procedure.