Excess of Seminomas Observed in Vietnam Service U.S. Military Working Dogs

Abstract

During the Vietnam War, US military working dogs served with their companion dog handlers in close proximity, sharing common exposures to war-related activity, many zoonotic infectious agents, chemical pesticides, phenoxy herbicides, and extensive use of therapeutic drugs. To gain insight into the effects of the Vietnam experience, we investigated the occurrence of neoplasms in military working dogs based on standard necropsy examination by the Armed Forces Institute of Pathology. We observed that these dogs experienced significant elevated risks for testicular seminoma and, independently, testicular dysfunction. Experimental evidence shows testicular dysfunction and impaired spermatogenesis in laboratory animals exposed to phenoxy herbicides, dioxin, or tetracycline, an antibiotic used extensively in military working dogs in Vietnam. Because an unexplained significant decrease in sperm quality in Vietnam veterans has been observed by the Centers for Disease Control, further research is warranted if we are to clarify military service in Vietnam as a risk factor for testicular dysfunction. The testis should be made a priority site in the study of Vietnam experience-related cancers. [J Natl Cancer Inst 82:1042–1046, 1990]