Deterioration and Metastasis of a Canine Transmissible Venereal Tumor in a Dog Associated with a CPV-2

2歲健康米格魯母犬，因實驗需求於背部皮下接種犬傳染性花柳性腫瘤(canine transmissible venereal tumor, CTVT)。腫瘤於接種2週後開始發生並持續生長，其生長模式與實驗室內其他腫瘤接種犬相近。腫瘤接種11週後該犬發生下痢之臨床症狀，經檢驗確診為犬小病毒之感染(canine parvovirus-2; CPV-2)。第13週時於體表接種之腫瘤原發位置附近出現散發性之小腫塊；且該犬隻健康狀況亦日益惡化，最後因人道考量執行安樂死並剖檢。該犬隻皮下、脾、肝、肺、與多處淋巴結均可見CTVT之轉移；脾臟與淋巴結出現淋巴萎縮、腸道上皮細胞亦有壞死灶，顯示出CPV-2感染之典型徵狀。CTVT本為一極少發生轉移之腫瘤，然而本病例中之犬隻因發生CPV-2之感染，繼而造成腫瘤之快速生長與轉移。由於CPV-2已知會造成宿主之免疫抑制，而CTVT之生長又與宿主的免疫反應息息相關，腫瘤生長與病毒感染問之交互作用值得深入的探討。

關鍵字

犬傳染性花柳性腫瘤；犬小病毒；轉移

並列摘要

Virus infection has been documented to be associated with tumor progression. A 2- year-old female beagle was inoculated in the dorsal flank with viable canine transmissible venereal tumor (CTVT) cells for routine laboratory tumor passage. Tumor masses were palpable 2 weeks after inoculation, then grew progressively, and the tumor size remained stable. Parvovirus (CPV-2) infection was diagnosed by RT-PCR at week 11 after tumor inoculation and, 2 weeks later, the primary tumors began to grow again. Besides, palpable tumor masses were found scattered around the primary tumor sites. Because of the deteriorating condition of the animal and the dramatic increase in tumor size and number, the dog was euthanized and venous blood collected for a complete blood count and serum chemistry analysis. Postmortem examination revealed a disseminated CTVT involving the subcutaneous tissue, spleen, liver, lung, and multiple lymph nodes, which was confirmed by histopathological examination and the presence of LINE gene insertion in the 5 end of c-myc gene, a characteristic of CTVT cells, shown using RT-PCR. Lymphoid cell depletion in the spleen and lymph nodes, and focal micro-necrosis of the cryptic epithelium of the small intestine were also seen. Blood analysis showed decreased levels of albumin and total blood protein and an extremely low lymphocyte count. Here, we report a rare case in which a stable CTVT became a devastating metastatic CTVT after a CPV-2 infection. The immunosuppressive effects of CPV-2 might account for the breakdown in the symbiotic balance between the CTVT and host that caused the stable tumor to develop into a metastatic cancer. The correlation between parvovirus infection and aggravated CTVT progression is worthy of further investigation.

並列關鍵字

CTVT ； CPV-2 ； metastasis

國際替代計量

Deterioration and Metastasis of a Canine Transmissible Venereal Tumor in a Dog Associated with a CPV-2

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