Allergic reactions after vaccination are considered as an important practical problem in dogs; however, their immunological mechanism has not been well understood. The present study was designed to investigate the relationship between
IgE reactivity to the
vaccines and immediate-type
allergic reactions after vaccination in dogs. Sera from 10 dogs that developed immediate-type
allergic reactions such as
circulatory collapse,
cyanosis,
dyspnea, facial
edema, and
vomiting within 1h after vaccination with non-
rabies monovalent or
combined vaccines and sera from 50 dogs that did not develop
allergic reactions after vaccination were collected. Serum
IgE reactivity to the injected
vaccines was measured by fluorometric ELISA using a mouse monoclonal anti-dog
IgE antibody. Then,
IgE reactivity to
fetal calf serum (FCS) and stabilizer
proteins (
gelatin,
casein, and
peptone) included in the
vaccines was measured in sera that had high levels of
IgE to the
vaccines. Levels of serum specific
IgE to the
vaccines in dogs with immediate-type
allergic reactions (59-4173 fluorescence units [FU], mean +/- S.D.: 992.5 +/- 1181.9 FU) were significantly higher than those in control dogs (38-192 FU, 92.4 +/- 43.3 FU) (P < 0.001). Of the eight dogs that developed immediate-type
allergic reactions and had high levels of serum specific
IgE to the
vaccines, seven had specific
IgE directed to FCS. The
IgE reactivity to the
vaccines in sera from these dogs was almost completely inhibited by FCS. The other one dog had serum
IgE directed to
gelatin and
casein included in the
vaccine as stabilizers. The results obtained in this study suggest that immediate-type
allergic reactions after vaccination in dogs were induced by
type I hypersensitivity mediated by
IgE directed to
vaccine components. In addition, FCS,
gelatin, and
casein included in
vaccines could be the causative
allergens that induced immediate-type
allergic reactions after vaccination in dogs.