1238 Scientific Reports: Original Study JAVMA, Vol 219, No. 9, November 1, 2001 SMALL ANIMALS T he effect of chemotherapy on acquired immunity has been studied in human adult and pediatric oncology patients. 1-11 Reports 1,8 indicate that vaccine- induced antibody titers against poliomyelitis, diphthe- ria, and tetanus are preserved in children undergoing antineoplastic therapy; however, immunity to varicella, influenza, hepatitis B, and measles is compromised. One early study 9 of pediatric patients with cancer revealed that patients were susceptible to varicella despite prior chicken pox infection, suggesting that immunity was lost because of disease or treatment. Results of a report by Feldman et al 10 indicated that of 115 previously vaccinated children receiving or having completed chemotherapy for various malignancies, 18% were seronegative for measles antibody, and 8% were seronegative for rubella antibody. Stored serum samples were available for 9 of the seronegative chil- dren and revealed that 5 were initially seropositive but became seronegative during or after completion of chemotherapy. In another study, 11 effect of chemother- apy on immunity to hepatitis B virus was studied in 49 children undergoing chemotherapy for acute leukemia. Eight of the children were seropositive for hepatitis B antibodies prior to initiation of chemotherapy. All eight became seronegative within 3 months of treatment ini- tiation. These studies support the hypothesis that chemotherapeutic agents may decrease antibody titers to common viruses. The clinical significance of these findings in veterinary cancer patients is unknown. It has been demonstrated that immunosuppression may result from presence of neoplastic disease itself, partic- ularly lymphoma, or from the use of chemotherapy drugs to treat such disease in dogs. 12-15 Dogs with lym- phoma have impaired cellular immunity, as assessed by in vitro lymphocyte blastogenesis, survival of allogene- ic skin grafts, and response to tuberculin challenge exposure after sensitization with Bacille Calmette- Guérin. 12,13,15 Likewise, impaired humoral immunity has been demonstrated in dogs with lymphoma. 12,13 Suppressed antibody responses to sheep RBC and to primary and secondary immunization with bacterio- phage were documented in dogs with lymphoma in previous studies. 12,14 Dogs with solid nonhematologic tumors did not have suppression of humoral immuni- ty. 12 Weiden et al 12 reported that baseline serum IgG concentrations for dogs with lymphoma were signifi- cantly lower than those of normal dogs, whereas those from dogs with nonhematologic solid tumors did not differ significantly. Similar comparisons were not made during the course of chemotherapy or after treatment. Treatment of dogs with lymphoma with single-agent L- asparaginase or combination protocols using vin- cristine, cyclophosphamide, and L-asparaginase result- Association between cancer chemotherapy and canine distemper virus, canine parvovirus, and rabies virus antibody titers in tumor-bearing dogs Carolyn J. Henry, DVM, MS, DACVIM; Dudley L. McCaw, DVM, DACVIM; Kenny V. Brock, DVM, MS; Aaron M. Stoker, MS; Jeff W. Tyler, DVM, PhD, DACVIM; Deborah J. Tate; Mary Lynn Higginbotham, DVM Objective—To determine the association between cancer chemotherapy and serum canine distemper virus (CDV), canine parvovirus (CPV), and rabies virus antibody titers in tumor-bearing dogs. Design—Prospective study. Animals—21 client-owned dogs with various malig- nancies and 16 client-owned dogs with lymphoma. Procedure—In study A, serum antibody titers were measured by use of hemagglutination inhibition (CPV titers) or serum neutralization (CDV titers) before and at least 1 month after initiation of chemotherapy. Baseline values were compared with values obtained from a control population of 122 healthy dogs seen for routine revaccination. Titers were considered protec- tive at ≥ 1:96 for CDV and ≥ 1:80 for CPV. In study B, serum IgG titers were measured by use of immunofluorescent assay (CDV and CPV titers) and rapid fluorescent focus inhibition test (RFFIT, rabies titers) at baseline and again at weeks 5, 8, and 24 of a standard chemotherapy protocol for treatment of lymphoma. An IgG titer of ≥ 1:50 was considered protective for CPV and CDV. An RFFIT titer of ≥ 0.5 U/ml was considered protective for rabies virus. Results—Significant changes were not detected in CDV, CPV, and rabies virus titers following chemother- apy in tumor-bearing dogs. Conclusions and Clinical Relevance—Results sug- gest that established immunity to CDV, CPV, and rabies virus from previous vaccination is not signifi- cantly compromised by standard chemotherapy used to treat tumor-bearing dogs. (J Am Vet Med Assoc 2001;219:1238–1241) From the Departments of Veterinary Medicine and Surgery (Henry, McCaw, Tyler, Tate, Higginbotham) and Pathobiology (Stoker), College of Veterinary Medicine, University of Missouri, Columbia, MO 65211; and the Department of Pathobiology (Brock), College of Veterinary Medicine, Auburn University, Auburn, AL 36849. Supported by the University of Missouri College of Veterinary Medicine, Department of Veterinary Medicine and Surgery Committee on Research, and by the Jeffrey Oncology Benevolent Fund. Presented in part at the 1999 American College of Veterinary Internal Medicine Annual Forum and at the 2000 Veterinary Cancer Society Annual Conference.