Safety of a new modified live virus vaccine against canine coronavirus

A new canine origin modified live canine coronavirus vaccine containing a C ornell strain of CCV with proven efficacy was subjected to extensive safety testing in 56 dogs of various ages, sexes, and breeds under laboratory con ditions, and more than 4,000 dogs under field conditions. At very high doses in various combinations with other commonly administered canine antigens, the CCV-MLV vaccine produced no neurologic or enteric cli nical signs of disease, no local or systemic reactions,and no untoward find ings at necropsy. Histopathological examination revealed no coronavirus in meninges,cerebrum, medulla, liver, lung, pancreas, or ileum, and CCV was no t isolated from feces. Neither leukopenia nor lymphopenia occurred after va ccination with CCV-MLV vaccine in combination with other MLV and unactivate d canine antigens. Even at very high doses, the vaccine did not interfere w ith the development of antibody titers to CPV or other vaccine antigens. Th ese results held true regardless of the injection route (intravenous, subcu taneous, intracerebral). When an equivalent of 200-300 times the field dose of the vaccine was given orally, no reversion to virulence was observed, and after two consecutive back passages the CCV vaccine virus was no longer recovered from feces. All dogs remained healthy during the study with no signs of enteric disease, d emonstrating that the virus did not revert to a virulent state. Both extensive field use, with over two million doses of this antigen admin istered, and the 4,000 + dog field trials additionally confirmed the excell ent safety of this antigen using CCV-MLV, CCV-CPVXL, or rDA(2)CPiP(XL), LCI vaccines (RM(R) Recombitck(TM) C6/CV).