Eighty-three cutaneous mast cell tumors in the dog were classified morphologically into three grades. The neoplasms were excised surgically, and the dogs were followed for 1500 days. Comparison of morphologic grade of tumor with survival time revealed significant differences among the three groups (p less than 0.00010). Comparison of sex and age (above and below ten years) with morphologic grade of tumor revealed no significant differences.

Spontaneous tumors in companion animals (dog and cat) offer a unique opportunity as models for human cancer biology and translational cancer therapeutics. The relatively high incidence of some cancers, similar biologic behavior, large body size, comparable responses to cytotoxic agents, and shorter overall lifespan are the factors that contribute to the advantages of the companion animal model. The tumor types that offer the best comparative interest include lymphoma/leukemia, osteosarcoma, STS, melanoma, and mammary tumors. With the increase in new therapeutic agents (traditional chemotherapy, gene therapy, biologic agents, etc.), the companion animal model can provide useful populations to test new agents where efficacy and toxicity can be examined.

Fifty-five dogs with lymphoma were treated using a doxorubicin-based sequential combination chemotherapy protocol. Complete response, partial response, and no response were seen in 46,4, and 5 dogs, respectively. The overall median remission duration and survival times were 36 and 51 weeks, respectively. Age, sex, weight, World Health Organization stage, World Health Organization substage (i.e., a = not ill, b = ill), serum calcium concentration, blood urea nitrogen concentration, breed, and protocol alteration secondary to toxicity were evaluated for prognostic significance. Univariate analysis of prognostic factors identified sex, World Health Organization substage, and serum calcium as statistically significant (P I .05) variables for both survival and remission duration. Upon multivariate analysis, only substage (P = .036) was a significant prognostic factor for remission duration, whereas, both substage (P = .006) and sex (P = .005) were significant prognostic factors for survival. times were shown; however, several reports of doxorubicin used as a sole chemotherapeutic agent for treatment of lymphoma, for reinduction of remission in failed lymphoma, or in combination with other drugs for induction or maintenance of lymphoma have indicated results comparable to several cyclic combination protocol^.^-'^ One study has shown an overall median survival time of 5 1 weeks when doxorubicin was included in a combination chemotherapy protocol.' There is controversy in the literature regarding prognostic factors for canine lymphoma. These factors have been summarized in a recent review article.I6 Previous studies have used univariate analysis, and therefore have not accounted for confounding variables when evaluating for prognostic factors. Multivariate analysis would help eliminate confounding variables.Because doxorubicin is effective against lymphoma, we evaluated the effect of including doxorubicin in a sequential combination chemotherapy protocol on survival time and remission duration. Additionally, several factors were evaluated for prognostic significance using multivariate analysis. Materials and MethodsFifty-five dogs with lymphoma underwent sequential combination chemotherapy without any prior treat- 289