Table 1.

Comparison of features of devil facial tumour disease (DFTD) and canine transmissible venereal tumour (CTVT)

DFTD	CTVT
∼ 16 years old	∼ 10 000 years old
Passed by biting	Passed during coitus
Close to 100% mortality	Not fatal (Progression, Stationary and Regression phases)
No significant infiltration of lymphocytes	Significant infiltration of lymphocytes during regression
Schwann cell origin	Haematopoietic origin (perhaps a macrophage cell)
MHC class I and class II negative	MHC class I and class II negative during progression
Epigenetic regulation of MHC genes	Epigenetic regulation of MHC genes
Sensitive to interferon-γ	Sensitive to interferon-γ
Unknown role of immunosuppressive cytokines	Cytokine regulation of immune response by transforming growth factor-β and interleukin-6
Low genetic diversity of host	Host is outbred