Use of tamoxifen in the control of canine mammary neoplasia

Ninety-three bitches which had undergone mammary tumour surgery were entered into a clinical trial to examine the effects of ovariohysterectomy (spaying) at the time of mammary surgery and the use of the drug tamoxifen in preventing the recurrence of the tumour and/or the development of new mammary tumours. Twenty-three of the bitches which had been spayed were allocated tamoxifen but only 18 of them complied with the treatment and in nine of these the treatment was stopped owing to side effects (mostly oestrogenic). Too few animals were studied to draw conclusions about the possible preventative effects of tamoxifen on mammary neoplasia, but the high percentage of bitches affected by oestrogen-like side effects may reduce the compliance of owners and prevent tamoxifen being widely used in dogs

Prognostic variables in canine multicentric lymphosarcoma

This paper presents the results of a prospective study to investigate the prognostic value of clinical staging, histological grading, immunophenotype, mitotic count and average numbers of argyrophilic nucleolar organiser region counts in dogs with multicentric lymphosarcoma treated with a standard chemotherapy protocol comprising vincristine, cyclophosphamide and prednisolone. Forty-nine dogs were treated according to the study protocol. Univariate and multivariate analysis with regression modelling was used to evaluate the prognostic importance of patient and tumour variables upon tumour response and relapse-free survival. Thirty-seven dogs (76 per cent) achieved a complete remission, seven (14 per cent) a partial remission and five (10 per cent) failed to respond to treatment. None of the variables examined had a statistically significant effect upon tumour response. Tumour immunophenotype was the only parameter found to have a significant influence on patient survival, the hazard ratio for T-cell versus B-cell immunophenotype was 3–99 with 95 per cent confidence interval from 1–399 to 11–372, P a 0–035