Canine transmissible venereal tumour: assessment of mast cell numbers as indicators of the growth phase.

Department of Paraclinical Veterinary Studies, University of Zimbabwe, Harare, Zimbabwe.
Veterinary Research Communications (Impact Factor: 1.36). 09/2006; 30(6):613-21. DOI: 10.1007/s11259-006-3309-1
Source: PubMed

ABSTRACT Mast cells are immune cells that are involved mainly in type 1 hypersensitivity reactions, and they have been implicated in tumour angiogenesis. In this study we assessed the presence of mast cell numbers and microvessel density during the progression and regression stages of natural spontaneous canine transmissible venereal tumours (CTVT). Mast cells were demonstrated by histochemical staining with toluidine blue, alcian blue and safranin O. Microvessel counts were demonstrated by immunohistochemical labelling with an antibody against the endothelial cell marker factor VIII. Mitotic cells, apoptotic cells and tumour infiltrating lymphocytes were counted from haematoxylin-eosin-stained sections. Tumour fibrosis was evaluated on Masson's trichome-stained sections. The results showed that progressing tumours had significantly higher mast cell counts and microvessel counts at the invasive edges of the tumours than did regressing tumours. In both the progressing and regressing tumours, microvessel counts were significantly positively correlated with mast cell counts. Regressing tumours had significantly higher mast cell counts of the whole tumour than progressing tumours. The results also showed that progressing tumours had significantly higher mitotic rate than regressing tumours, and fibrosis and apoptosis were significantly higher in regressing tumours than progressing tumours. There were no significant differences between the biochemical and haematological values of dogs with progressing and regressing tumours. These results suggests that mast cells play a role in CTVT progression probably by promoting vascularization at the invasion front during the progression phase, and that mast cell count could be used as one of the histological factors to indicate growth stage of CTVT.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: ntroduction and aim - Canine transmissible venereal tumour (CTVT) is a neoplasm with unique features. Despite occasio- nal spontaneous regression of the tumour, veterinarians often have to treat it by chemotherapy. This study aimed to evaluate a new bi-weekly vincristine treatment in comparison to the traditional weekly protocol for CTVT. Materials and methods - 30 dogs with CTVT were divided into two groups: 10 dogs in the control group A and 20 dogs in the experimental group B, treated with weekly and bi-weekly 0.025 mg/kg iv of vincristine sulphate respectively. All animals we- re monitored during treatment by gross evaluation of the tumour, cytology and haematic samples (CBC and hepatic profile). Therapy was suspended when neoplastic cells were no longer found in smears. Results and discussions - In group B, complete remission was obtained for all the dogs after 2.2 ± 0.3 administrations of vincristine. Regarding group A remission was obtained in 9 dogs after 3.6 ± 0.7 administrations. Only mild side effects were observed with no significant differences between groups. A bi-weekly vincristine regimen may be an alternative or elective treat- ment for CTVT, being successfully applied to animals in which weekly therapy is impractical. A bi-weekly schedule is advanta- geous for both owners and animals.
    Rivista ufficiale della SCIVAC 07/2008; 22(4):13-18. · 0.10 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study evaluated the morphology and immunohistochemistry of 85 canine cutaneous histiocytic tumours. The tumours were classified morphologically as either canine cutaneous histiocytomas (71 tumours) or canine cutaneous histiocytic sarcomas (14 tumours). The immunohistochemical analysis was conducted on paraffin sections using an antibody panel (against MHCII, CD18, CD79αcy, CD3 and E-cadherin). Histochemical staining with toluidine blue and Gomori silver impregnation was also performed. A follow-up was conducted via surveys. The histiocytic origin of the tumour cells was confirmed in 65 of the canine cutaneous histiocytomas and in 4 of the canine cutaneous histiocytic sarcomas. The tumours that had been misdiagnosed as canine cutaneous histiocytomas included plasmacytomas, epitheliotropic T-cell lymphomas and undetermined entities. The tumours misdiagnosed as canine cutaneous histiocytic sarcomas included plasmacytomas and non-epitheliotropic T-cell lymphomas, but the majority of them remained undetermined. The canine cutaneous histiocytomas showed MHCII, CD18 and E-cadherin expression, but in several of the tumours, the expression of CD18 or E-cadherin was confirmed in only a small percentage of the tumour cells. The regressing canine cutaneous histiocytomas showed increased T- and B-lymphocyte infiltration, a decreased mitotic index, transport of the MHCII molecules from the cytoplasm to the cell membrane and loss of E-cadherin expression in the tumour cells. The canine cutaneous histiocytic sarcomas showed both high morphological diversity and expression of MHCII and CD18. Two of the evaluated histiocytic sarcomas also showed expression of E-cadherin. In conclusion, immunohistochemistry, including analysis of MHCII, CD18 and the lymphocytic markers CD3 and CD79, should be performed for the diagnosis of canine cutaneous histiocytic tumours. The expression of E-cadherin in canine cutaneous histiocytic sarcomas suggests an origin of the tumour cells among Langerhans cells.
    Veterinary Research Communications 11/2014; 39(1). DOI:10.1007/s11259-014-9622-1 · 1.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Canine transmissible venereal tumour (CTVT) is a contagious venereal tumour of dogs, commonly observed in dogs that are in close contact with one another, or in stray and wild dogs that exhibit unrestrained sexual activity. CTVT represents a unique, naturally transmissible, contagious tumour, where the mutated tumour cell itself is the causative agent and perpetuates as a parasitic allograft in the host. Clinical history, signalment and cytological features are often obvious for establishing a diagnosis though biopsy and histological examination may be needed in atypical cases. Most cases are curable with three intravenous injections of vincristine sulphate at weekly intervals. The role of stray and wild dogs makes the disease difficult to control and necessitates sustained animal birth control in stray dogs along with prompt therapy of the affected dogs. This review captures the manifold developments in different areas embracing this fascinating tumour, including its biology, diagnosis and therapeutic alternatives.
    Veterinary and Comparative Oncology 08/2013; DOI:10.1111/vco.12060 · 1.45 Impact Factor