Clinicopathological study of canine transmissible venereal tumour in leishmaniotic dogs

Introduction : Canine transmissible venereal tumour is occasionally observed in leishmaniotic dogs, and Leishmania amastigotes can be harboured in canine transmissible venereal tumour cells. Objectives : The aim of this paper was to investigate the clinicopathological significance of the association of both diseases. Methods : Nineteen dogs affected by canine transmissible venereal tumour and canine leishmaniasis were studied retrospectively. Results : In these dogs, the tumour manifested a large size and often aggressive behaviour (42%) and no predictive sign of spontaneous regression was observed. Sporadic Leishmania amastigotes were found within the canine transmissible venereal tumour in three cases, probably transported by infected macrophages often infiltrating the tumour. A high Leishmania parasitisation of canine transmissible venereal tumour was observed in two other cases and verified by immunohistochemistry. Clinical Significance : Canine transmissible venereal tumour is a tumour of the dog able to harbour a large number of Leishmania parasites. Alternatively, the systemic disease (canine leishmaniasis) may lower the immune defence against malignancy (canine transmissible venereal tumour).     

Mitosis and apoptosis in canine cutaneous histiocytoma and transmissible venereal tumour

Cell proliferation and apoptosis in canine cutaneous histiocytomas and transmissible venereal tumours were examined in twenty cases. The Ki-67 immunohistochemistry and Tunel methods were used to detect mitotic activity and apoptosis, respectively. The number of Ki-67 immunoreactive cells was 11.65 (+/- 1.1706) in canine cutaneous histiocytomas and 17 (+/- 2.1751) in transmissible venereal tumours. The mean values of apoptotic cells for canine cutaneous histiocytomas and transmissible venereal tumours were 13.25 (+/- 1.8758) and 8.52 (+/- 1.1007), respectively. It was considered that mitotic activity and apoptotic indices were useful in differentiation of canine cutaneous histiocytomas and transmissible venereal tumours. The correlation values for canine cutaneous histiocytomas and transmissible venereal tumours were 0.359 (+/- 0.330) and -0.232 (+/- 0.344), respectively. No significant (P > 0.05) correlation was found between mitosis and apoptosis in these two tumour types.     

Canine transmissible venereal tumour: a review

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.     

Role of exfoliative cytology in the diagnosis of canine transmissible venereal tumour

The objectives of this study were to evaluate the role of exfoliative cytology in the diagnosis of canine transmissible venereal tumour and to improve the success rate of surgical excision of this tumour. The technique was used to screen 360 dogs and, at the time of surgery, 34 clinical cases. Seventy-five per cent of the cases detected by screening were described as early stage disease in comparison with 23 per cent of cases reported by owners. The value of exfoliative cytology at the time of surgery to determine tumour cell removal was demonstrated by the reduction in local tumour recurrence from 22 per cent to 8 per cent. The technique is, therefore, recommended for use in screening dogs for canine transmissible venereal tumour and in determining the extent of surgical removal. However, more work is needed to assess its applicability in practice by determining its sensitivity, specificity and predictive values of a positive and negative test answer.     

Metastatic transmissible venereal tumour in dogs

This report presents six cases of canine transmissible venereal tumour (TVT) in the genital organs with metastasis to extragenital locations. These extragenital sites were the skin, lymph nodes, spleen, tonsils, liver and lung. Foci of metastasis were found in six different organs in one case, two organs in another case and one organ in the remaining four cases. Multiple tumour nodules were, however, found in certain organs such as the skin and spleen. The extragenital tumours were identified as TVT on the basis of their histological similarity to the primary genital tumours. Metastasis appeared to be mainly by lymphatic pathways and by oral implantation. Résumé. Ce rapport présente six cas de tumeur vénérienne transmissible (TVT) dans les organes génitaux avec métastase aux endroits extragénitaux. Ces endroits extragénitaux étaient la peau, les nouds lymphatiques, la rate, les amygdales, le foie et les poumons. Des foyers de métastase ont été trouvés dans six organes différents dans un cas, dans deux organes dans un autre cas et dans un organe dans les quatre cas restant. On a, cependant, trouvé des tumeurs multi-nodulaires dans certains organes tels que la peau et la rate. Les tumeurs extragénitales ont été identifiées comme TVT en se basant sur leur similarité histologique aux tumeurs génitales primaires. La métastase semblait ětre principalement par voies lymphatiques et par implantation orale. Zusammenfassung. Dieser Bericht stellt sechs Fǎlle dar von ùbertragbar venerischem Hunde-Tumor (TVT) in den Geschlechtsorganen mit Métastase an extragenitalen Stellen. Dièse extragenitalen Stellen waren die Haut, Lymphknoten, Milz, Mandeln, Leber und Lunge. Herden von Metastasen fand man in sechs verschiedenen Organen in einem Fall, zwei Organen in einem anderen Fall und in einem Organ in den ùbrigen vier Fǎllen. Zahlreiche Tumorknǒtchen (Noduli) wurden jedoch in gewissen Organen wie Haut und Milz gefunden. Die extragenitalen Tumoren waren als TVT identifiziert auf Grund ihrer histologischen ǎhnlichkeit mit den primaren Geschlechtstumoren. Metastasen traten hauptsàchlich durch lymphatische Bahnen und durch orale Einpflanzung ein.     

A retrospective evaluation of four surgical methods of treating canine transmissible venereal tumour

A total of 109 lesions were treated in a total of 109 dogs and bitches using simple surgical excision or diathermy, with or without the simultaneous removal of the gonads. Evaluation of the case, 49 months after surgery, showed that 35 (32.1 per cent) of the tumours had regressed completely whilst 74 (67.9 per cent) had recurred. Excision using diathermy was the more effective treatment irrespective of whether the gonads were removed. There was a significant difference in the frequency of recurrence and the time interval for it to recur (P < 0.05 and P < 0.25 respectively) when the methods of treatment were compared, however castration of either males or females had no significant effect upon the frequency of recurrence.     

Evaluation of a genetic assay for canine transmissible venereal tumour diagnosis in Brazil

The canine transmissible venereal tumour (CTVT) is a transmissible cancer that is spread between dogs by the allogeneic transfer of living cancer cells. The infectious agents in CTVT are the living cancer cells themselves, which are transmitted between dogs during coitus. CTVT first arose several thousand years ago and the disease has a global distribution and is frequently observed in dogs from Brazil. We evaluated the utility of a LINE‐MYC quantitative polymerase chain reaction for diagnosis of CTVT cases in Brazil. Our analysis indicated that the LINE‐MYC rearrangement was detectable in all CTVT samples but not in their corresponding hosts. This genetic assay proves to be a useful tool for providing a definitive molecular diagnosis of CTVT, which presents with varying degrees of aggressiveness and invasiveness in different host dogs and can therefore be a diagnostic challenge in some specific cases.     

Parvovirus-induced regression of canine transmissible venereal sarcoma

In 1981, during the worldwide canine parvovirus (PV) epizootic, canine transmissible venereal sarcomas growing in Beagles in a colony regressed earlier than expected after the dogs became infected with PV. Subsequent studies revealed that modified-live PV vaccine (feline panleukopenia virus) was capable of preventing tumor transplantation when the vaccine was inoculated simultaneously with the tumor in a site distant from the implantation site. However, the PV vaccine had no effect if it was inoculated 3 or 18 days after the tumor was transplanted.     

The distribution of C-bands in canine transmissible venereal tumor cells

Colchicine-arrested metaphase preparations, derived from canine transmissible venereal tumor (TVT) cells grown in culture, were characterized based on the occurrence and distribution of constitutive heterochromatin. Analysis of the data with regard to the distribution of C-bands in the pericentric, interstitial and telomeric segments revealed a nonrandom distribution along the arms of many chromosomes with the bulk of the bands occurring in the centromeric region. The frequency of C-banded regions differed from those reported for normal dog cells and both primary and transplanted tumors. These results suggest that similar nondifferentially-stained TVT karyotypes do not necessarily exhibit identical distribution of constitutive heterochromatin.     

A case of ocular canine transmissible venereal tumor

A 1-year-old, intact female mixed-breed dog was presented to St. George’s University Small Animal Clinic in Grenada for a third eyelid mass. The dog was diagnosed with a rare ocular transmissible venereal tumor (TVT) and concurrent anaplasmosis, ehrlichiosis and dirofilariasis. Treatment with vincristine sulfate resulted in complete resolution of the TVT.     

Heat shock proteins in canine transmissible venereal tumor

SDS-PAGE, Western blot analysis and immunohistochemical staining were used to detect heat shock proteins (HSPs) 60, 70 and 90 in canine transmissible venereal tumor (CTVT). Tissues tested for HSPs included: (1) tissues from different growth phases of CTVT tumors artificially induced in dogs; (2) tissues from other canine tumors; (3) normal dog tissues. Our results indicate that HSP 60 was consistently higher in CTVT cells in regressing phase than those in progressing phase. However, no detectable antibody response specific to the tested HSPs was found in the sera from CTVT-laden dogs in different growth phases. Although levels of the HSPs were all detectable in CTVT cells, only 60 and 70 were higher in CTVT cells than in normal tissues. In addition, none of the HSPs were detected in cells from five other canine tumors. These data suggest that canine HSP 60 and 70 are potential markers for CTVT and HSP 60 is appear to be involved in CTVT regression.PCR was used to confirm the existence of CTVT cells using primers designed to cover the sequence between the 5' end of c-myc near the first exon and the 3' end outside the LINE gene. Only CTVT samples were positive for this sequence; samples from other tumors and normal tissues were negative. The sequenced PCR products indicated that CTVT from Taiwan and other countries exhibited over 98% sequence homology. This reconfirms that, worldwide, all CTVT cells are very similar.     

Metastasis of a transmissible venereal tumour to the pituitary

This report presents a case of metastasising transmissible venereal tumour (TVT) with lesions of the penis, lip, spleen and pituitary. The clinical picture is outlined and the associated diagnostic radiographic procedures used to reach a final diagnosis of a space–occupying lesion in the region of the pituitary are described. A definitive diagnosis of a metastasizing TVT was reached by histopathological examination and it is concluded that the pituitary and spleen metastases are examples of the systemic dissemination of the original penile tumour whilst the lip lesion probably arose by direct contact.     

The chromosomes of the transmissible venereal tumour of dogs in Ibadan, Nigeria

Cytogenetic studies on 11 transmissible venereal tumours in seven dogs in Ibadan, Nigeria, are reported. The number and the morphology of the chromosomes, as shown by the metaphase cells, revealed that the tumour cells have similar cytogenetic features to those reported in other parts of the world. The suggestion of common sources of infection for the animals in the different geographical locations of the world was supported.     

Immunohistochemical characterization of intraocular metastasis of a canine transmissible venereal tumor

Little has been published on intraocular metastasis of transmissible venereal tumors (TVT) in dogs. This report presents a 4-year-old male Labrador Retriever with a previous history of subcutaneous TVT which underwent total remission after treatment with vincristine. The dog presented with clinical signs of uveitis and increased intraocular pressure (IOP) in both eyes. After enucleation of the left eye, a diagnosis of TVT was made based on morphology, histology and immunohistochemistry (IHC). IHC staining for vimentin, S-100 protein, cytokeratin and HMB45 was performed to differentiate this lesion from TVT, lymphoma, melanoma, carcinomas, neurogenic tumors and fibrosarcoma. The IHC findings supported the diagnosis of TVT for this round cell tumor.     

Use of a murine xenograft model for canine transmissible venereal tumor

OBJECTIVE: To develop a murine model for canine transmissible venereal tumor (CTVT). ANIMALS: Thirty-three 6-week-old NOD/LtSz-scid (NOD/SCID) mice and seven 6-week-old C57BL/6J mice. PROCEDURE: Samples of CTVT were excised from a 3-year-old dog and inoculated SC into ten 6-week-old NOD/SCID mice to induce growth of xenograft transmissible venereal tumor (XTVT). To establish mouse-to-mouse transmission, samples of XTVT were removed and inoculated SC into 4 groups of 6-week-old NOD/SCID mice and into a control group. Samples of CTVT were also inoculated into immunocompetent C57BL/6J mice for a mouse antibody production (MAP) test. The canine and xenografted tumors were evaluated cytologically and histologically, and polymerase chain reaction was performed for detection of the rearranged LINE/c-MYC junction. RESULTS: 8 of 10 NOD/SCID mice that were inoculated with CTVT developed tumors 3 to 10 weeks after inoculation. In the second-generation xenograft, all mice developed tumors by postinoculation day 47; 1 X 10(6) of XTVT cells were enough to create a xenograft. Metastases developed in 4 of 20 mice. Xenografted and metastatic tumors retained cytologic, histologic, and molecular characteristics of CTVT. Results of the MAP test were negative for all pathogens. CONCLUSION: We established an NOD/SCID murine model for XTVT and metastasis of CTVT. This model should facilitate study of tumor transplantation, progression, and metastasis and should decrease or eliminate the need for maintaining allogenic transfer in dogs.